This website is using a security service to protect itself from online attacks The action you just performed triggered the security solution There are several actions that could trigger this block including submitting a certain word or phrase You can email the site owner to let them know you were blocked Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page Metrics details An unusually damaging Mw 4.9 earthquake occurred on November 11 2019 in the south east of France within the lower Rhône river valley an industrial region that hosts several operating nuclear power plants The hypocentre of this event occurred at an exceptionally shallow depth of about 1 km Here we use far-field seismological observations to demonstrate that the rupture properties are consistent with those commonly observed for large deeper earthquakes In the absence of strong motion sensors in the fault vicinity we perform numerical predictions of the ground acceleration on a virtual array of near-fault stations These predictions are in agreement with independent quantitative estimations of ground acceleration from in-situ observations of displaced objects Both numerical and in-situ analyses converge toward estimates of an exceptional level of ground acceleration in the fault vicinity and explain the unexpectedly significant damage We observed only a few (<5) displaced slabs at C2 and C3 while all slabs remained stable at C4 and C5 The orange polygon is the area where displaced rocks are observed b Flow chart describing the strategy to compute near-fault ground acceleration Finally we obtain a set of ground acceleration time histories on a dense array of virtual stations we collect in-situ observations providing independent estimates of the ground acceleration such as displacements of funeral slabs in cemeteries and displaced rocks above the fault Both numerical analysis and in-situ measurements of displaced objects converge toward exceptional ground acceleration exceeding gravity in the immediate fault vicinity Our study provides new insights on seismic hazard due to superficial seismicity in stable continental regions We use a kinematic representation of the rupture process the rupture velocity and the local slip velocity most of them are constrained by observations except the slip velocity that needs to be calibrated based on past earthquake studies indicating that the slip obtained from InSAR is primarily seismic The duration of the slip acceleration phase is poorly constrained but we checked that the ground acceleration time series presented hereafter are not sensitive to this parameter in the considered frequency range (<5 Hz) (Right panel) Pictures of the outcropping Hauterivian and Valanginian marls and limetsones Top: simulated median values of the Peak Ground Acceleration (PGA) between 0 and 5 Hz on the array of virtual stations computed over 2000 realizations of rupture models expressed in terms of the standard deviation of the log10 values The dashed rectangle represents the surface rupture projection The thick black polygon line is the area where displaced rocks are observed in agreement with the observed Intensity of VIII in the fault vicinity In order to obtain independent estimations of the ground acceleration we collected in-situ observations of displaced rigid objects that fulfill the following criteria: (1) there is evidence that displacement is due to the earthquake; (2) the objects loosely lie on the ground; (3) their structure is simple enough so that their displacement can be related to ground acceleration using simple mechanical concepts We compiled a database of displaced rocks and a database of funeral slabs displacements for comparison with the simulated seismic slip and ground acceleration The slabs can move with respect to ground if: that is when the inertial force is sufficient to induce sliding of the slab The arrows on the bottom figure indicate the direction and amplitude of forces transmitted to the slab at different time steps The ground displacement (light gray) and slab displacement (dark gray) diverge at the arrival of the stopping phase generated by the rupture arrest The relative slab displacement is shown in purple indicating a final displacement of 6 cm in the direction N168° c 2D-probability density function of simulated PGA (geometrical mean of horizontal components) and modeled relative final slab displacement obtained from 2000 realizations of rupture models The median final relative slab displacement measured on field (4.5 cm) yields a median PGA value of 4.8 m/s2 (CI 68% 4.3–5.4 m/s2) in the cemetery during the Le Teil earthquake The 2019 Mw4.9 Le Teil earthquake occurred in a stable continental region at unusually shallow depth (~1 km) Such superficial events are rare and thus their rupture characteristics are very poorly documented The level of ground motion that they can produce is basically unknown We demonstrated that the average rupture properties (stress drop rupture- and slip- velocity) are consistent with the ones commonly observed for large deeper earthquakes We also showed that the unusually shallow rupture with generation of energetic seismic waves up to the ground surface resulted in an exceptional and destructive level of ground acceleration exceeding gravity on some localized patches in the immediate fault vicinity as evidenced by the consistency between the numerical predictions and the body of in-situ observations our simulation results point on a fast decay of motion amplitude with fault distance for the first few kilometers the simulated ground motion shows a high level of heterogeneity that is fully related to the rupture characteristics along the fault plane (distribution of slip and rupture velocity future geological and geophysical analyses should characterize the extent and thickness of the geological units and the seismogenic potential of the local faults so as to constrain the probability of a superficial earthquake (either tectonic or anthropogenic) in the immediate vicinity of the power plants the level of the low frequency plateau Ω0 is: where t is the travel time of the considered wave and Q is the quality factor of the considered wave we obtain that the rupture duration for P-waves is between 0.84 fc and fc assuming a symmetric circular crack rupture model and a rupture velocity VR between 50% and 90% of the S-wave velocity VS (consistent with the inferred average VR of ~1.8 km/s and our velocity model) an average duration of 2.0 s (68% CI: 1.4–3.4 s) We next compute the corner frequency for various classes of source-station azimuths, and compare the azimuthal variations with the theoretical predictions for a simple horizontal line source (Fig. S2) i is the take off angle and θ is the source-station azimuth Despite the uncertainty on fc(θ) and considering various values of i and VR, the results indicate a bilateral rupture (Fig. S2) Note that the resolution of the very shallow earth structure (up to 300 m depth) is poor so that we do not model potential surface rock alteration that may enhance ground acceleration above 5 Hz Note also that the Triassic bedrock depth is not resolved by the inversion The array is composed of 234 stations with inter-stations distance of 500 m A distance between the fault points of 60 m ensures stability of the computed ground motion up to 5 Hz It supports strong ground motion to be of the order of the gravity during Le Teil earthquake References on previous worldwide observations of displaced rocks for larger earthquakes are also provided in Supplementary References We conduct numerical simulations to model the observed funeral slab displacements We exclude from our analysis slab observations associated with rotation and focus on slabs backing onto N70-oriented headstones Since the fundamental frequency of the slab is >100 Hz (considering a granite slab with dimension 200 × 100 × 8 cm) we modeled it as a mass particle with three degrees of freedom is in frictional contact with the EW-NS plane which is animated by the three-dimensional seismic ground motion The friction law we used is the standard Coulomb friction model without tangential force regularization we obtain the differential equation of motion of the undamped particle: Convergence is achieved for a time step <10−3 s a displacement of 4.5 cm corresponds to a simulated median horizontal PGA of 4.8 m/s2 Accordingly the 0.2 value of friction coefficient μ best approximates the observations Small variations of μ may explain part of the variability of the field observations for noise data analysis and determination of the velocity model) The Matlab codes used to generate individual results are available under request to M.C NESS1: a Worldwide Collection of Strong‐Motion Data to Investigate Near‐Source Effects The pan-European Engineering Strong Motion (ESM) flatfile: compilation criteria and data statistics The SCEC Broadband Platform validation exercise: Methodology for code validation in the context of seismic hazard analyses Sira C. et al. Rapport macrosismique n°4, Séisme du Teil (Ardèche) 11 novembre 2019 à 11 h 52 locale, Magnitude 5,2 ML (RENASS), Intensité communale max VII-VIII (EMS98), BCSF-RENASS-2020-R2. https://doi.org/10.13140/RG.2.2.27570.84166 (2020) Transposing an active fault database into a seismic hazard fault model for nuclear facilities – Part 1: Building a database of potentially active faults (BDFA) for metropolitan France Ritz, J. F. et al (2020). Surface rupture and shallow fault reactivation during the 2019 Mw 4.9 Le Teil earthquake, France, Commun. Earth Environ., https://doi.org/10.1038/s43247-020-0012-z Cornou, C. et al. (2020). Rapid response to the Mw 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, Comptes Rendus Geosci., https://doi.org/10.31219/osf.io/3afs5 Shallow seismicity in stable continental regions Ampuero, J.-P. et al. The November 11 2019 Le Teil, France M5 earthquake: a triggered event in nuclear country, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18295, https://doi.org/10.5194/egusphere-egu2020-18295 Earthquakes triggered by surface quarrying-the Wappingers Falls The 1994 Cacoosing Valley earthquakes near Reading Pennsylvania: a shallow rupture triggered by quarry unloading Mining-induced seismicity at open pit mines in Kuzbass (Bachatsky earthquake on June 18 Global review of human-induced earthquakes The November 2017 Mw 5.5 Pohang earthquake: a possible case of induced seismicity in South Korea Source and Site Characteristics of Earthquakes That Have Caused Exceptional Ground Accelerations and Velocities Exceptional Ground Motions Recorded during the 26 April 2008 Mw 5.0 Earthquake in Mogul A new asymptotic method for the modeling of near-fault accelerograms Use of ray theory to calculate high-frequency radiation from earthquake sources having spatially variable rupture velocity and stress drop Near-Source Ground Motion along Strike-Slip Faults: Insights into Magnitude Saturation of PGV and PGA Tectonic stress and the spectra of shear waves from earthquakes Theoretical basis of some empirical relations in seismology Allmann, B. P., and P. M. Shearer (2009). Global variations of stress drop for moderate to large earthquakes, J. Geophys. Res. 114, https://doi.org/10.1029/2008JB005821 Stress‐Drop Variability of Shallow Earthquakes Extracted from a Global Database of Source Time Functions Source pulse enhancement by a deconvolution of an empirical Green’s function High-Frequency Directivity Effect for an Mw 4.1 Earthquake Widely Felt by the Population in Southeastern France Anomalously large complete stress drop during the 2016 Mw 5.2 Borrego Springs earthquake inferred by waveform modeling and near-source aftershock deficit Seismic stereometry reveals preparatory behavior and source kinematics of intermediate-size earthquakes Evidence for and implications of self-healing pulses of slip in earthquake rupture Chounet, A., M. Vallée, M. Causse, and F. Courboulex (2017). Global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity, Tectonophysics, https://doi.org/10.1016/j.tecto.2017.11.005 A Kinematic Source-Time Function Compatible with Earthquake Dynamics A cohesive zone model for dynamic shear faulting based on experimentally inferred constitutive relation and strong motion source parameters On Scaling of Earthquake Rise‐Time Estimates Bouchon, M., D. Hatzfeld, J. A. Jackson, and E. Haghshenas (2006). Some insight on why Bam (Iran) was destroyed by an earthquake of relatively moderate size, Geophys. Res. Lett. 33, https://doi.org/10.1029/2006GL025906. Eyewitness account of surface faulting during the earthquake of 28 October 1983 Wilkinson, M. W. et al (2017). Near-field fault slip of the 2016 Vettore Mw 6.6 earthquake (Central Italy) measured using low-cost GNSS, Sci. Rep. 7, https://doi.org/10.1038/s41598-017-04917-w Near-Fault Peak Ground Velocity from Earthquake and Laboratory Data Causse M., F. Cotton and P. M. Mai (2010). Constraining the roughness degree of slip heterogeneity, J. Geophys. Res., https://doi.org/10.1029/2009JB006747 Fault slip distribution and fault roughness: fault slip distribution and fault roughness Rayleigh wave three-component beamforming: signed ellipticity assessment from high-resolution frequency-wavenumber processing of ambient vibration arrays Wathelet, M. (2008). An improved neighborhood algorithm: parameter conditions and dynamic scaling, Geophys. Res. Lett., 35. https://doi.org/10.1029/2008GL033256 Calibration astronomique du Valanginien et de l’Hauterivien (Crétacé inférieur):implications paléoclimatiques et paléocéanographiques Effect of fault dip and slip rate angles on near-source ground motions: why rupture directivity was minimal in the 1999 Chi-Chi Modification of empirical strong ground motion attenuation relations to include the amplitude and duration effects of rupture directivity Observations of vertical ground accelerations exceeding gravity during the 1997 Umbria-Marche (central Italy) earthquakes Near-Field Ground Motions from the July 2019 Ridgecrest EMS98 intensity estimation of the shallow Le Teil earthquake Ground Motion to Intensity Conversion Equations (GMICEs): A Global Relationship and Evaluation of Regional Dependency On the use of logic trees for ground-motion prediction equations in seismic-hazard analysis A probabilistic method for the estimation of earthquake source parameters from spectral inversion: application to the 2016–2017 Central Italy seismic sequence Variability of earthquake stress drop in a subduction setting A dynamic model for far-field accelerations Kaneko, Y., and P. M. Shearer (2015). Variability of seismic source spectra, estimated stress drop, and radiated energy, derived from cohesive-zone models of symmetrical and asymmetrical circular and elliptical ruptures., J. Geophys. Res., 120, https://doi.org/10.1002/2014JB011642 Dujardin, A. et al (2019). Optimization of a Simulation Code Coupling Extended Source (k−2) and Empirical Green’s Functions: application to the Case of the Middle Durance Fault. Pure Appl. Geophys., https://doi.org/10.1007/s00024-019-02309-x Finite difference computation of traveltimes in very contrasted velocity models: a massively parallel approach and its associated tools Geopsy: a User‐Friendly Open‐Source Tool Set for Ambient Vibration Processing A simple method to calculate Green’s functions for elastic layered media Dynamic stress variations due to shear faults in a plane-layered medium Finite element simulation of dynamic instabilities in frictional sliding contact In STLE/ASME 2003 International Joint Tribology Conference (pp (American Society of Mechanical Engineers Digital Collection Micro-scale roughness effects on the friction coefficient of granite surfaces under varying levels of normal stress Meso-Scale Shear Physics in Earthquake and Landslide Mechanics Download references Christophe Larroque and Jean-François Ritz for fruitful discussions We thank Romain Jolivet for providing the InSAR slip distribution before publication This work was partially financed by SINAPS@ research project (ANR-11-RSNR-0022) and by the Ministry of Ecological Transition (research program “Prévention des Risques” J.R.G.’s contribution was partially supported by Fonds européen de développement régional (FEDER) (SISM@LP-Swarm research project analyzed and interpreted farfield seismological recordings and data of modeled slab displacements contributed to the acquisition and dissemination of seismic noise data computed and interpreted the velocity model estimated macroseismic Intensity and analyzed databases of accelerometric data designed the field survey of displaced rocks contributed to the ground acceleration simulations All authors contributed to the results interpretation and reviewed the paper The authors declare no competing interests Peer review information Primary handling editor: Joe Aslin Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations Download citation DOI: https://doi.org/10.1038/s43247-020-00089-0 Anyone you share the following link with will be able to read this content: a shareable link is not currently available for this article Sign up for the Nature Briefing newsletter — what matters in science The eCapt-Rhône project uses renewable hydrogen production and CO2 captured from Holcim’s cement plant in Le Teil to generate e-methanol It is set to become the first large-scale plant in France to produce 138 kilotons (kt) of e-methanol per year The project aims to replace about 20% of current French methanol consumption by providing locally produced e-methanol to industrial firms thereby reducing CO2 emissions by 70%. The plant’s goal is to capture 100% of CO2 emitted – around 200,000 tons – annually it received a grant from the EU Innovation Fund The eCapt-Rhône project is driven by three technological processes: The capture brick will be located at Le Teil cement plant while the hydrogen and e-methanol production infrastructure will be installed at the Osiris chemical platform located just 100 kilometers from the plant “The eCapt-Rhône project has an important role to play in the industry both by making the large-scale capture of CO2 in a cement plant a reality and by producing e-methanol directly amidst industrial consumers.” OLYMPUS is a flagship project in Holcim’s European decarbonization roadmap It will lead to the development of storage capacity in southern Europe The Carbon2Business project at our cement plant in Lägerdorf Germany aims to capture more than 1.2 million tons of CO2 emissions annually Go4ECOPlanet will install a unique facility to capture 100% of CO₂ emissions generated during the production of clinker – the key ingredient in cement production The KOdeCO net zero project aims to make Holcim’s Koromačno plant the first to produce net-zero cement in Croatia and the Mediterranean the GO4ZERO project will deploy an innovative carbon capture technology at our plant in Obourg and transport CO2 for offshore storage under the North Sea CarboClearTech will sequester 700,000 tons of residual CO2 emissions at our plant in Martres-Tolosane SEE ALL STORIES Holcim is a global leader in innovative and sustainable building solutions with net sales of CHF 26.4 billion in 2024 Our 65,000 employees are driven by our purpose to build progress for people and the planet across our regions to improve living standards for all We partner with our customers to offer the broadest range of advanced solutions from sustainable building materials ECOPact and ECOPlanet all the way to Elevate’s advanced roofing and insulation systems Lettre de bénédiction datant de 1896 de la première pierre de la nouvelle église du Teil In Le Teil, Ardèche (southern France), a page is being turned, but a new one is also being written. Weakened by the earthquake of 2019 the church in the commune of Le Teil is currently being demolished A new church is to be built just a few yards away blessed the foundation stone of this church,” it reads “But it's always moving to know that you're part of a history (...) We feel part of a history; there were people before us and there will be people after us!” The original document will be handed over to the Ardèche departmental archives A photocopy will be made and incorporated into one of the foundation stones of the new Le Teil church on which work is due to start in September 2024 The text found in the old church will be joined by a new text explaining the context of the demolition and reconstruction of a new church which he readily describes as a “testimony of faith,” is a beautiful way of “putting everything under the gaze of Christ.” The new building should welcome its first Mass on Christmas 2025 It will be a true symbol of hope for a commune that is very attached to its religious heritage Articles like these are sponsored free for every Catholic through the support of generous readers just like you Please make a tax-deductible donation today Help us continue to bring the Gospel to people everywhere through uplifting Catholic news a magnitude 5 earthquake occurred near the village of Le Teil in the Rhône River Valley in southern France producing an unexpected surface rupture with ground displacement Université Côte d'Azur and Terradue (1) had the opportunity to use all modern seismological and geological techniques available to study this historically unprecedented seismic event published on 27 August 2020 in Communications Earth & Environment reveals that the earthquake was caused by the reactivation of the ancient La Rouvière fault The fault formed during an extensional tectonic period some 20-30 million years ago during the Oligocene epoch the fault experienced a reverse faulting movement (compression) with an average surface displacement of about 10cm both vertically and horizontally Scientists estimate that the event nucleated at a shallow focal depth of approximately 1km which explains why the rupture along the fault was able to reach the surface and cause considerable damage despite the moderate-magnitude (3) (the accurate position of the earthquake's focus is presently being studied by another research team) The results raise the possibility that other faults could be reactivated in France and Western Europe and produce surface displacements whereas the risk of earthquakes with surface rupture was until now considered as highly improbable To better assess the probability of such events several teams of scientists in France are performing palaeoseismological investigations looking for evidence of past earthquakes along such faults 10.1038/s43247-020-0012-z are not responsible for the accuracy of news releases posted to EurekAlert by contributing institutions or for the use of any information through the EurekAlert system Copyright © 2025 by the American Association for the Advancement of Science (AAAS) Metrics details a densely populated area with many industrial facilities including several nuclear power plants seismological and interferometric synthetic-aperture radar observations indicating that the earthquake occurred at a very shallow focal depth on a southeast-dipping reverse-fault We show evidence of surface rupture and up to 15 cm uplift of the hanging wall along a northeast-southwest trending discontinuity with a length of about 5 km these lines of evidence suggest that the Oligocene La Rouvière fault was reactivated Based on the absence of geomorphic evidence of cumulative compressional deformation along the fault we suggest that it had not ruptured for several thousand or even tens of thousands of years Our observations raise the question of whether displacement from surface rupture represents a hazard in regions with strong tectonic inheritance and very low strain rates the level of instrumental seismicity in the Rhône River Valley was low and a few damaging historical earthquakes had been documented This also suggested that the rupture could have reached the surface which is uncommon for both such a magnitude and for the region we present the first seismological and geodetical data that helped discover tenuous surface ruptures over a length of about 5 km and then describe the observations performed in the field Our study brings new highlights on shallow earthquakes that can occur in stable continental regions and raises important questions in terms of seismic hazard analyzes and also in terms of the tectonic processes which are at the origin of this event A: Plio-Quaternary volcanism; B: Miocene–Pliocene sediments; C: Oligocene sediments; D: Mesozoic sediments; E: Paleozoic crystalline basement (Massif Central); F: major faults (NE termination of the Cevennes fault system (CFS) in red CF and MF for Cévennes Fault and Marsanne Fault Black dots indicate main population centers No surface ruptures were reported for these historical earthquakes The local magnitude of the 2019 Le Teil earthquake varies from ML 5.2 (ReNaSS) to ML 5.45 (LDG). The moment magnitude is Mw 4.9 (this study) and the maximum epicentral intensity is VIII (EMS98) with a wide region (15 km diameter around Le Teil) impacted by at least an intensity VI [BCSF: Bureau central Sismologique Français: http://www.franceseisme.fr/donnees/intensites/detailsseisme.php?IdSei=930] We benefited from the data of four additional seismological stations located less than 25 km away from the epicenter Epicentral solutions were mapped by using a non-linear exploration scheme inverting exclusively the P and S wave arrival times of these four closest stations we tested many different 1D velocity models accounting for the uncertainty in the crust properties we could estimate the uncertainty on the absolute location of the epicenter a Map with stations used (green triangles) and the focal mechanism corresponding to the best solution found b Plot of focal mechanism solutions in an RMS versus depth graph in displacement (cm) bandpass filtered between 0.03 and 0.08 Hz Observed records are in gray and computed in red For each station the three components are displayed (N and “vel” or “acc” (blue labels) means that the original record was in velocity (broadband) or acceleration (strong motion) Pre-earthquake image is from 31 October 2019; post-earthquake image is from 12 November 2019 (12 days baseline) The black lines correspond to faults after the Aubenas geological map4 The white line defines the ~5-km-long northern section of the La Rouvière Fault (LRF) matching with the InSAR discontinuity suggesting that this along-strike evolution of vertical fault displacement vs the accommodation width is mainly controlled by source processes and likely reflects variations of slip along the fault plane Given the high density of vegetation that covers a large part of the area we first focused on roads and paths crossing the InSAR discontinuity and found spot evidences of surface rupture To complement our observations and image the continuity of the rupture below the forest cover a, d Field photographs showing surface ruptures affecting an asphalt road (flat pop-up structure) and a dirt road (extrados-fissures) (evidences # 7 and # 2, respectively, see location Fig. 4) e Ultra-high-resolution (1 mm) laser scans at the same locations Blacks arrows in b correspond to profiles shown in c; red arrows in e points to N090–N100°E trending fissures (the two northeastern are those shown in d) The thin black lines correspond to the four topographic profiles shown in f Note the position of cracks on top of what we interpreted as a 5 m long bulge affecting the dirt road f Topographic profiles extracted from laser scans showing the vertical components (the red dotted line in f corresponds to the suspected reverse-fault rupture controlling the bulge of the dirt road) and D the average surface displacement expressed in SI units L = 4600 (length determined visually from interferograms) to 5200 m (detectable length from the analysis of InSAR profiles) W = 1400 to 2800 m (considering a focal depth of 1000 ± 500 m and assuming that the rupture extended over 500 m in depth from the hypocenter) D = 0.10 m (mean vertical displacement from Fig. 5) to 0.14 m (accounting for a 45° rupture dip) accounting for the shallowness of the rupture and determined from density and shear wave velocities in the stratigraphic layers surrounding the hypocenter (Cornou This yields a geological equivalent moment magnitude Mw between 4.7 and 5.0 which is consistent with the moment magnitude estimated from the seismological data while “F” refers to open fissures affecting asphalt roads In the field, the fault scarp associated with the LRF exhibits several normal fault planes in competent lower Cretaceous (Barremian) carbonates exhumed by agricultural land use and/or differential erosion where carbonates are juxtaposed to marl-rich units (Fig. 4b) These fault planes strike mainly N30–40°E and dip between 45 and 60°E with steep slickenlines indicating in a few places an unambiguous normal cumulative movement with a slight left-lateral component As already pointed out from the InSAR analysis these observations show that the Le Teil earthquake rupture occurred along the ancient Oligocene normal LRF any clear evidence of previous cumulative reverse-faulting activity prior to Le Teil event such as recent reverse-fault scarps when it is preserved from anthropogenic activity corresponds to that of an ancient cumulative normal fault scarp that has undergone differential erosion through time by specifying earthquake recurrence (if any) Addressing those geodynamic issues will mobilize a series of large-scale geological and geophysical data and modeling approaches the 11 November 2019 Mw 4.9 Le Teil earthquake is a historically unprecedented earthquake in France and surrounding region because it displays very low magnitude and shallow surface-rupturing characteristics and secondly because comprehensive seismological and surface rupture observations could be performed with modern techniques the Le Teil earthquake represents a unique opportunity and a turning point to better define the seismicity to consider for hazard studies the risk of surface-rupturing events in France or similar stable continental regions is until now considered to be negligible in most regions due to the very low strain rate measurements The different methods we used in this work are integrated into the description of the results and detailed in the Supplementary Information files Geological (surface ruptures evidences) and InSAR data generated or analyzed during this study are included in this published article (and its Supplementary Information files) Sismicité de la region d’Arette (P.A.) et mécanismes au foyer Modern Approaches in Solid Earth Sciences (eds France M5 earthquake: a triggered event in nuclear country Transposing an active fault database into a seismic hazard fault model for nuclear facilities—Part 1: Building a database of potentially active faults 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J. A new paradigm for large earthquakes in stable continental plate interiors. Geophys. Res. Lett. 43, https://doi.org/10.1002/2016GL070815 (2016) Impact of gravity forces and topography denudation on normal faulting in Central–Western Pyrenees: insights from 2D numerical models Erosion-induced isostatic rebound triggers extension in low convergent mountain ranges Malcles, O. et al. Determining the Plio-Quaternary uplift of the southern French Massif-Central; a new insights for intraplate orogen dynamics. Solid Earth Discuss. https://doi.org/10.5194/se-2019-99 (2020) Download references the “Failles actives France” program (FACT) of the Transverse Seismicity Action (ATS) of the French Seismologic and Geodetic Network RESIF the Institute of Radiological Protection and Nuclear Safety (IRSN) and the following research laboratories: Geosciences Montpellier Sentinel-1 satellite data were freely provided within the framework of the European Commission COPERNICUS program We thank IRSN and EDF for making available the data of their seismologic stations and Quartier families for allowing us to work on their lands Institute of Radiological Protection and Nuclear Safety Christophe Larroque & Bertrand Delouis contributed to collecting and analyzing field data analyzing terrestrial laser scanner and LiDAR data contributed to collecting and analyzing seismological data Download citation DOI: https://doi.org/10.1038/s43247-020-0012-z Vous utilisez un ancien navigateur. Ce site risque de ne pas s'afficher correctement. Mettez à jour votre navigateur pour améliorer votre expérience. Le Teil site near the epicentre of the 11 November 2019 earthquake. Le Teil in the Ardèche has 8000 inhabitants and was the epicentre of an earthquake. The village experienced high-magnitude seismic activity on 11 November 2019 at 11:52 am: local magnitude 5.4, and moment magnitude 4.9. There were no casualties, but major damage to property. People had to be displaced and the earthquake was felt as far away as Montélimar, some 7 km away (about 40,000 inhabitants). The village is located on a known fault zone in the Rhone Valley. However, this was an event of rare magnitude in France. The last earthquake of this magnitude dated back to 1967, in Arette in the Bearn foothills of the Pyrenees, with a local magnitude of 5.3. The earthquake in Le Teil had implications for the Cruas-Meysse nuclear power plant, 14 km away, which was shut down for a month, causing serious concern among the population in the region. 3D view of the fault system around the Le Teil quarry showing the intersection zones at depth. Geological model generated by GeoModeller.  BRGM researchers created mechanical models to take into account the particular configuration of the surface topography, but also the history of the volumes of material excavated by the quarrying operation since 1850 and the geometry of the fault system. Soil humidity data acquired by the European SMOS satellite and modelling of the variations in height of the unsaturated zone using the BRGM ComPASS code showed that water infiltration affected the recharge, with hydraulic overpressure reaching a maximum precisely at the intersection of the fault system. This is an example of seismic action in the intraplate domain, with the possibility of simultaneous surface fractures on two distinct faults. ComPASS code simulation of the hydraulic pressure variations on the La Rouvière fault in the month preceding 11 November 2019. The second stage of the work from February to May 2021 confirmed the initial programme and refined the results, in particular locating the area of maximum hydraulic overpressure at the intersection of the fault system. This research confirmed the BRGM hypothesis: the earthquake could have been triggered hydraulically. BRGM demonstrates that there is of course no reason to dismiss a tectonic origin of the Le Teil earthquake. But it could also have been a tremor triggered by an external event: in this case, the hydraulic load due to a period of heavy rainfall in the month preceding the earthquake. More broadly, the earthquake not only revealed the need to reassess the hazard in the area, but also reopened a debate on the nature of seismic activity in mainland France in the intraplate domain. BRGM is among the French organisations that collect seismological observations for France, and its role naturally includes this type of work. This is also a highly original cross-disciplinary project combining geology, geophysics, geomechanics, seismology and hydraulics, and it opens up a new field of research on the subject of intraplate hydroseismicity on a European scale, all in connection with global climate change. Such hydroseismic hypotheses have already been put forward in the United States in the last 20 years. They have now been corroborated here in mainland France. Subscribe to our newsletter and receive our news every month! Volume 10 - 2022 | https://doi.org/10.3389/feart.2022.1029160 This article is part of the Research TopicApplications of Wave Propagation Simulation in Complex Geological MediaView all 7 articles The 2019 Le Teil earthquake is an illustrative example of a moderate (MW 4.9) yet damaging event occurring at shallow depth (≈1 km) in a region with little to no geophysical data available using a high-fidelity wave propagation code we performed numerical simulations of the Le Teil earthquake in a highly uncertain framework investigating several seismic sources and geological set-ups a point-source model and an extended kinematic fault model were compared The latter aspect was investigated by comparing a 1D-layered to a 3D geological model Those models were enhanced with random fluctuations in order to obtain three alternative non-stationary random geological fields The synthetic waveforms obtained from regional geophysical models were globally coherent with the recorded ones The extended fault source model seemed more realistic than the point-source model some geological random fields improved the synthetics’ agreement with the recordings the three random field samplings led to a high variability in induced ground motion responses Given the computational burden of high-fidelity simulations we used two dimensionality reduction methods namely the Principal Component Analysis (PCA) and a deep neural network (3D UNet) The methods were applied to a database of 40,000 3D geological random fields Both the PCA and the 3D UNet condensed the variability of the 3D geological fields into a few components These were sufficient to reconstruct the original fields with great accuracy the seismic response arising from the propagation throughout the reconstructed fields was in excellent agreement with the response of the original geological fields in more than 75% of the dataset By building a structured ensemble of complex geological fields from their reduced representation it may become possible to find a relationship between the reduced representation and the generated ground motion our study proves the interest of dimensionality reduction to perform uncertainty analyses in complex geological media Such large parameter uncertainties prevent the exploitation of the full potential of modern computer software capable of reproducing complex seismic wave propagation with high accuracy when correctly constrained it is legitimate to explore the abilities of regional-scale models in regional numerical simulations For uncertainty quantification purposes though a large number of simulations is necessary Yet the cost of high-fidelity simulations on large and complex domains - increasing with spatial resolution - prevents computationally demanding approaches such as Monte Carlo methods we show that it is possible to encode the geological database into a few number of meaningful features those features generate very good reconstructions of the initial database that retain all the necessary information without degrading the propagated seismic response (A) corresponds to Section 2 and Section 3 while (B) refers to the work done in Section 4 and Section 5 Section 2 describes the numerical model used to simulate the Le Teil earthquake while results are presented in Section 3 Section 4 details the geological database and the dimensionality reduction methods Outputs of these methods are analyzed in Section 5 The discussion in Section 6 concludes the manuscript 1) Numerical simulation of ground motion responses with different configurations of the seismic source and the geological model 2) Dimensionality reduction of heterogeneous geological fields and its impact on simulated ground motion including the available recording stations and the trace of the la Rouvière fault FIGURE 2. Map of the region affected by the 2019 Le Teil earthquake, in South-Eastern France. The computational domain considered in this paper is indicated with the dotted box. Velocimeters and accelerometers are shown with black triangles (details in Supplementary Table S1) The Le Teil earthquake was recorded over 22 stations within 70 km from the fault (Supplementary Table S1). Some velocimeters (e.g. PAUL and BOLL in Figure 2) saturated while recording and they could not be considered for further analyses This study focuses on stations located out of the sedimentary basin (OGDF CRU1) since its absence from our models is likely to impact synthetic ground motions inside the basin The hypocenter was obtained from the results of the waveform inversion (44.5188° N, 4.6694° E, depth -1.3 km, see Delouis et al., 2021). In this study, two types of seismic sources were compared, with a target seismic moment M0 = 2.47 ⋅ 1016 N.m. Namely, a double-couple point source was assumed with strike = 48°, dip = 45°, and rake = 88° (Delouis et al., 2021) The fault was represented as a 7 km-long and 4 km-deep plane with a 60° dip and reaching the surface at its highest point It was further discretized in triangular patches A bidirectional rupture front starts from the nucleation point located at the hypocenter Each patch activates when it is reached by the rupture front under the constraint that its final slip corresponds to the one obtained from the InSAR inversion Final slip given by the kinematic fault model It presents a thin sedimentary subsurface layer with low velocity (VS = 1730 m/s) overlying a 25 km thick crustal layer (VS = 3560 m/s) The average ratio between P- and S- wave velocities is 1.69 The bedrock is described by S-wave velocities of 4650 m/s TABLE 1. 1D geological model used by the CEA-LDG to locate seismic events. Described in more details in (Duverger et al., 2021) VP (black) and VS (grey) velocity profiles for the 1D geological model (continuous line) 3D geological model in station VIVF (dashed line) FIGURE 5. 3D geological model for S-wave from (Arroucau 2020) (A) Original model; (B) Addition of random heterogeneities (correlation lengths of 10 km horizontally and 1 km vertically The 3D random field computation is made highly efficient by the use of the spectral representation (Shinozuka and Deodatis 1991; de Carvalho Paludo et al., 2019) a centered Gaussian random field u determined by its autocovariance function R can be decomposed as a sum of independent identically distributed random variables (ϕn)−N≤n≤N where R̂ is the Fourier transform of the autocovariance function R and Δk the unit volume in R3 Random fields were thus generated in a few seconds for the whole domain with a 2 km × 2 km × 0.2 km resolution They were later interpolated on the Gauss-Lobato-Legendre (GLL) points as part of the computation process The 80 km × 92 km × 79 km computational domain was discretized on a hexahedral mesh with 18.3 million elements With a minimum S-wave velocity of 2180 m/s and 5 GLL points per element this mesh allowed wave propagation up to 5 Hz Simulations were run on 2048 cores AMD Milan @2.45 GHz (AVX2) operated by the Très Grand Centre de Calcul (TGCC simulations were obtained in 61,440 h CPUs for 60 s of simulated signal This section presents the simulation results of the Le Teil earthquake obtained with regional geological models of increasing complexity (Section 3.1) and several samplings of random fields (Section 3.2) Frequency response spectra of the numerical simulation (in red) obtained with the 1D geological model and a point source Comparison with seismograms records (in black) Velocities are given in the East-West (E-W) and vertical (Z) directions for stations OGDF (A) and OGCB (B) Yet, the use of the 3D geological model leads to other issues. Supplementary Figures S2A,B indeed show high velocity peaks at the beginning of the signal The peaks’s amplitude is higher than the maximal velocities recorded during the earthquake the horizontal Peak Ground Velocity (PGV) was 5 times higher than records in station OGDF and 7 times higher in station OGCB The velocity peaks indicate that the energy content of the signal is concentrated with the first wave arrivals This results from the smoothness of the 3D geological model: the absence of inter-layer discontinuity prevents the multiple wave refractions and reflections that tend to spread the energy distribution over time To better represent the time duration of the signal, the point-source was replaced by an extended fault model and used in conjonction with the 3D model. Figure 7 shows a satisfactory agreement between the recorded and synthetic frequency response spectra. As expected, the successive nucleation of points on the fault plane creates an energy distribution that avoids the large peaks observed with the point source (Supplementary Figure S3) The horizontal PGV was hence reduced to 1.15 and 5 times the recorded one in stations OGDF and OGCB respectively Frequency response spectra of the numerical simulation (in red) obtained with the 3D geological model and a kinematic fault model Random fields were added to the 1D geological model to create small scale heterogeneities Random fields were drawn independently in each of the three layers thus possibly creating sharp interfaces between layers We chose the point-source description over the kinematic fault model to limit the interactions between the source and the medium which may alter the results independently from path effects Figure 8 shows that introducing heterogeneities reduces the early peaks’ amplitude compared to the signals generated with the homogeneous 1D geological model Heterogeneities also limit the duration and scale of the surface wave oscillations This behaviour is interpreted as a consequence of the diffraction induced by heterogeneities that spread the energy content and limit the wave guide effect the signal obtained with a heterogeneous medium seems more realistic than those originating from the homogeneous model Numerical results in station OGDF obtained with a point source and the 1D geological model enhanced with random fields (blue) Comparison with the results of the homogeneous 1D geological model (grey) and the records filtered at 5 Hz (black) However, one cannot claim that one sampling of a random field can represent the variability of all possible heterogeneities. To assess the possible impacts of heterogeneities while maintaining reasonable computational costs, two new random fields were drawn and added to the 1D geological model. Supplementary Figures S4A,B show the ground motion response in station OGDF with those random fields One can notice that those samplings tend to increase the amplitude of the late oscillations compared to those obtained with the homogeneous medium the influence of random fields on the surface wave oscillations was not consistent between samplings thereby ensuring our heterogeneous models were realistic the first and second random field samplings were close to the GMPE The third sampling led to SA slightly higher than the upper bound of the GMPE for stations CRU1 and OGDF it is noteworthy that the record in station OGCB was also out of the confidence interval we had no reason to reject the third sampling based on the sole analysis of the SA FIGURE 9. Pseudo Spectral Acceleration (SA) at 1 s in 3 stations (CRU1, OGDF, OGCB). Mean horizontal SA for records (pink cross), 1D model (black dots), 1D model with random fields (colored dots), and a GMPE (grey line) with the associated confidence interval (Berge-Thierry et al., 2003) Moreover, Figure 9 shows that both the homogeneous 1D geology and the second sampling of the heterogeneous geology were close to the records Although comparing the SA did not lead to a preference for one of these two models we showed above that the heterogeneous model was able to reduce the surface wave oscillations the three random fields showed a high variability that may create synthetic seismograms closer to the recorded ones seismograms worse than those obtained with the homogeneous geological model a more systematic analysis of random heterogeneities involving machine learning techniques is necessary to better apprehend the relationship between heterogeneities and their impacts on ground motion To analyze the wide range of ground motion variability created by the addition of random fields on geological models it would be necessary study thousands of heterogeneous geological models the computational cost of high-fidelity simulations makes this direct approach unaffordable we propose to reduce the dimensionality of geological fields we built a database of 40,000 heterogeneous S-wave velocity fields (described in Section 4.1) we applied the PCA (Section 4.2) and a 3D autoencoder (Section 4.3) to this database We additionally built a similar dataset of 4000 geological fields for test purposes The same source time function was used with τ = 0.1 The velocity values described in the previous paragraph ensured that the numerical propagation of seismic waves was accurate up to a 5 Hz frequency (with 7 GLL points per element synthetic ground motion was recorded on a 32 × 32 regular grid of virtual sensors placed at the surface By considering geological fields as 1D vectors the PCA loses the spatial organisation of 3D geological fields one may therefore expect a greater dimensionality reduction with a 3D autoencoder than a PCA The autoencoder can be viewed as a nonlinear extension of the PCA since it creates a reduced representation of the input in what is called a latent space The encoder associates the 3D input with the latent representation and the decoder reconstructs a 3D field from the latent representation while trying to minimize the error between the input and the reconstruction Our 3D autoencoder is built from the architecture of the 3D UNet developped by Wolny et al., 2020. We conducted an exhaustive search of the main hyperparameters to adapt the proposed architecture to our objectives. Our final encoder is composed of 6 blocks that increase the number of channels of the inputs from 1 to 256. As represented in Figure 10 each block is composed of two convolutional layers Blocks are separated by max pooling layers to reduce the dimensionality from 32 × 32 × 32 to 1 × 1 × 1 A batch size of 16 was found to produce lower reconstruction errors than larger batches for both training and validation datasets 3D UNet autoencoder with 6 blocks of double convolutions (4 million parameters in total) Skip connections between the encoder and decoder are done via concatenation The database of 40,000 geological fields was split in 90% of training and 10% of validation data Inputs were centered and normalized by 4 times the standard deviation moving values approximately into [ − 0.5 The training loss was simply composed of the L1 reconstruction error The Adam optimizer was used with a learning rate of 2 ⋅ 10–4 Training the network for 1000 epochs on 4 Nvidia Ampere A100 GPUs took 9.5 h This corresponds to 8.6% of the minimum velocity value Each row represents one geological field from the test dataset of 4000 samples (B) reconstruction with a PCA with 1024 principal components (C) reconstruction with a 3D UNet autoencoder the large error derived from a biased reconstruction by the neural network Reconstruction error on 4000 test geological fields using a PCA with 512 components (in grey) and 1024 components (in brown) boxes extend from the 1st to the 3rd quartile When investigating the reconstruction error pixel by pixel, it appeared that on the one hand, the PCA led to a reconstruction error that was well distributed around 0. Some pixels overestimated the velocity while others underestimated it (Supplementary Figure S6A). On the other hand, the 3D UNet committed a global error on the mean velocity value leading to pixels that were all under- or over-estimated (Supplementary Figure S6B) A RMSE smaller than 135 m/s was guaranteed for 75% (resp 72%) of the geological fields in the test database with the PCA reconstruction (resp This can be explained by the lack of small-scale heterogeneities that should have diffracted and reflected seismic waves Signals propagated through the reconstructed geological field were therefore less attenuated than the reference ones the wave arrival times were very well reproduced since the mean velocity was correctly reconstructed by the PCA FIGURE 14. For the sensor depicted by the black triangles in Figure 13 velocity ground motion along the North-South component Black: ground motion obtained with the input VS field Red: ground motion obtained with the VS field reconstructed by (A) PCA and (B) 3D UNet GOFs are represented in the frequency (FEG and FPG) and time (TEG and TPG) domain for the enveloppe (top) and phase (bottom) ground motion responses of the geological field reconstructed by the 3D UNet differ from the input mostly in terms of phase Since the 3D UNet underestimated (for this specific sample) the mean velocity the reconstructed signal was delayed with respect to the reference one amplitudes were well reproduced thanks to the good reconstruction of small-scale heterogeneities Considering the sparsity of available geological data a 1D layered geological model was not rich enough to accurately simulate the Le Teil earthquake Geological models can be improved by the addition of random fields that however yield a large ground motion variability Quantitative analyses of the variability induced by heterogeneous models would require hundreds or thousands of simulations PCA is a common dimensionality reduction method that is well adapted to extract features from 3D random fields it needed at least 1024 components in the current setting to retain good reconstruction abilities A greater reduction could be obtained with a dedicated 3D auto-encoder architecture (3D UNet) that gave promising results We showed that the main ground motion characteristics of the Le Teil earthquake can be reproduced using regional geological models The frequency response spectra were in satisfactory agreement with the recorded seismograms induced surface waves with high-amplitude oscillations These oscillations were significantly reduced when adding random fields to the geological model therefore leading to more realistic signals this model needed to be used in conjunction with the kinematic fault model to ensure that the signal energy was correctly spread over time the point source model led to peak ground velocities much larger than the recorded ones We also found some differences between ground motion generated from a point source and from an extended kinematic fault model We interpret these differences as plausibly coming from the low depth of the Le Teil fault Although the addition of random fields on the 1D geological model could reduce the unrealistic surface waves oscillations this effect was not necessarily consistent between stations and between different random fields samplings a larger diversity of random fields was necessary to better understand the impacts of heterogeneities on ground motion As a preliminary step to conduct numerical simulations on hundreds of heterogeneous geological fields we showed that both the PCA and the 3D UNet were able to reduce the fields dimensionality while preserving their main features the PCA already produced geological fields with small reconstruction errors It appeared that the PCA smoothes small scale heterogeneities similarly to temporal signals losing their high frequency content when being decomposed by PCA Although it did not have a major impact on the generated ground motion the only way to alleviate this issue would be to increase the number of principal components Since our aim is to run simulations from reduced representations of 3D random fields this is not the path we would like to pursue the larger the number of simulations to sample all possible heterogeneous fields and one cannot afford running tens of thousands of high-fidelity simulations Different conclusions were drawn for the geological fields reconstructed by the 3D UNet The reconstruction error was somewhat similar to the one obtained with the PCA with more fields having an even better reconstruction the 3D UNet was able to produce sharp outputs with small scale heterogeneities being well preserved This mainly arises from the use of the L1 norm that favors large components during the neural network training Although the 3D UNet produced biased reconstructions for geological fields with low coefficients of variation this can be easily corrected by adding a regularization term to the neural network loss function The major advantage of the 3D UNet over the PCA is its greater dimensionality reduction power Although we acknowledge the computation power required to train the 3D UNet the current architecture produces latent variables of size 256 which is significantly lower than the number of PCA components From the reduced representation of geological fields we envision building a structured ensemble of heterogeneous geological fields We could therefore run a limited number of high-fidelity simulations Then thanks to the dimensionality reduction it would be possible to exhibit a relationship between the geological field and the ground motion response it may even be possible to inverse this relationship to infer real soil heterogeneities from the study of recorded ground motion The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: https://doi.org/10.5281/zenodo.6983054 and FL contributed to the design and implementation of the research and to the analysis of the results All authors contributed to manuscript revision The authors thank Clara Duverger and Pierre Arroucau for providing and explaining the geological models and Amaury Vallage for his help processing seismograms They acknowledge the computational ressources provided by the CEA and the preliminary study of Eddy Terrasse and Roberto Paolucci for the discussions on the 3D Le Teil simulations The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/feart.2022.1029160/full#supplementary-material Supplementary Figure S1 | Results of the numerical simulation (in red) obtained with the 1D geological model and a point source Comparison with seismograms records (in black) filtered at 5 Hz Supplementary Figure S2 | Results of the numerical simulation (in red) obtained with the 3D geological model and a point source Comparison with seismograms records (in black) filtered at 5 Hz Supplementary Figure S3 | Results of the numerical simulation (in red) obtained with the 3D geological model and a kinematic fault model and vertical (Z) directions in stations OGDF (A) and OGCB (B) Supplementary Figure S4 | Velocities obtained with two random fields added to the 1D geological model in OGDF station. 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Available at: https://arxiv.org/abs/2103.14158 Google Scholar Bertin M and Clouteau D (2022) Machine learning opportunities to conduct high-fidelity earthquake simulations in multi-scale heterogeneous geology Received: 26 August 2022; Accepted: 01 November 2022;Published: 22 November 2022 Copyright © 2022 Lehmann, Gatti, Bertin and Clouteau. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use distribution or reproduction in other forums is permitted provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited in accordance with accepted academic practice distribution or reproduction is permitted which does not comply with these terms *Correspondence: Fanny Lehmann, ZmFubnkubGVobWFubkBjZW50cmFsZXN1cGVsZWMuZnI= Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher 94% of researchers rate our articles as excellent or goodLearn more about the work of our research integrity team to safeguard the quality of each article we publish Ardèche in south-east France will welcome the first passenger train to stop in the department in 50 years today (August 29 The service to Le Teil station will only be used to reverse trains on their way to Gard It is part of SNCF’s decision to re-open a local line and serve four daily round trips from Pont-Saint-Esprit to Avignon (Vaucluse) and one to Nîmes (Gard) SNCF is expected to open a second regional line and it is hoped Le Teil will then be included as a passenger stop in 2024 a local association representing the interests of public transport users which has long campaigned for local train stops said: “The fact the department is ‘train-free’ was so ingrained in our minds that we’d come to believe they would never come again.” SNCF chose Le Teil as the station is already equipped with technology to reverse trains The station is due to undergo a €12million renovation SNCF uses it around 200 times a year when the line on the left side of the Rhône is under maintenance The return of a passenger service has been talked about since 2010 but many locals had lost hope Cutpsa members plan to meet at Le Teil on August 28 to celebrate the event “My job is now to let people understand they will soon be able to hop on a train from Ardèche,” said Mr Pallier “People had lost faith that it would ever happen over the years.” ‘Smelly’, ‘exceptionally clean’: Your views on French train conditions Are trains in France legally required to have AC during summer months? French train firm SNCF offers railcards at 50% off for one week only Her body was found outside initial search area by a walker over the weekend Recent power cut in Spain and Portugal is warning to holidaymakers to ensure they are prepared for worst-case scenario Metrics details An Author Correction to this article was published on 18 February 2021 An Addendum to this article was published on 22 October 2020 This article has been updated Earthquake occurrence is ultimately controlled by tectonic stress load Le Teil earthquake in southern France occurred in an area where strain rates are relatively low Human operations can produce increases in stress load and degradation of strength on nearby active faults Here we present estimates of the rupture geometry and source directivity of the Le Teil earthquake based on differential synthetic aperture radar interferometry and seismic data We find that almost two centuries of mass removal at a nearby cement quarry likely provided the required stress change to hasten the occurrence of the Le Teil earthquake by more than 18,000 years We suggest that further mass removal in the area might lead to even stronger earthquakes by activating deeper sectors of the same fault plane we analyzed the source characteristics of the Le Teil earthquake and investigated the possible link with the nearby industrial activities Our results indicate that the extraction activity could have triggered the Le Teil earthquake we estimate a clock advance larger than 18,000 years and residuals for line-of-sight surface displacement for ascending (ASC) and descending (DESC) orbits DinSAR interferograms The fault trace of the two retrieved rupture planes is indicated by magenta lines while the black contour depicts the Le Teil quarry b The dislocation resulting from the inversion of the ground deformation data is displayed in both perspective and plane view releasing most of the seismic moment during the Le Teil earthquake this suggests that an earthquake on this fault could have occurred anyway sometime in the future but the quarry activity triggered it There is no information on past seismic events on this fault and no speculation can be done on the possible recurrence time of sizeable earthquakes associated with it by assuming an average rigidity of G = 32 GPa for the crust the horizontal stressing rate \(\dot \sigma = G{\it{\dot \epsilon }}\) associated with the mentioned shear strain rate \({\it{\dot \epsilon }}\) would be ~15 Pa/year the projections of this stress rate on the fault correspond respectively to ~13 Pa/year and ~6 Pa/year for the normal σn and shear τ stress components The estimated cumulative maximum Coulomb stress change on the fault due to the total mass subtraction is 0.19 MPa by 2011 corresponding to maximum normal Δσn = 0.21 MPa and shear stress Δτ = 0.11 MPa By accounting for the uncertainty in the estimated volumes (see “Methods” section) these stress values can be considered reliable within ±10% considering that about 10% of the total stress change derives from the mass removal in 1833–1946 the larger uncertainty associated with the reconstruction of the initial reference topography (see Methods and Supplementary Information) would only affect the final stress calculation by <5% these results allow stating that the rock extraction from the quarry likely have triggered the 2019 Le Teil earthquake by dramatically accelerating the loading of the fault and hastening its unlocking we note that even considering the upper extreme for the stress drop (Δτ = 2.0 MPa this would not change our conclusion and the hypothesis of a significant anthropogenic effect on the origin for the earthquake still holds The increment of the shear stress on the faults of the 2019 earthquake caused by the tectonic forces (blue line; exaggerated vertical scale), starting from the previous (unknown) earthquake, and by the Le Teil quarry activity (0.19 MPa; gray line). The anthropogenic shear stress is computed at the point marked by the small black square in Fig. 3 The total shear stress on the fault is represented by the red line The horizontal gray line on top marks the fault strength the above results cannot exclude that the dynamic shaking from the quarry blasts possibly could have had a role in contributing to trigger the event either in terms of short-term dynamic stress (due to transient stress perturbation) or by material fatigue due the repeated shaking could be interpreted as an indication that the stress change associated with the quarry extraction was enough to overcome the fault strength at shallow depth but not sufficient to exceed the fault resistance deeper than that In this hypothesis and especially if on deeper portions of the fault there is near-critical preexisting tectonic stress additional future mass removal might trigger deeper slip possibly causing a stronger earthquake than the one that occurred on November 11 Note that the maximum uplift is about 11 cm while the amplitude of the subsidence is appreciably smaller the area affected by westward motion is rather extended while eastward motions are more concentrated on the SW side of the LRf and shows a maximum displacement of about 7 cm data were preliminarily resampled over a regular grid (70 m spacing in all the considered area) to reduce the computation load Starting from a nonlinear inversion algorithm based on the Levenberg–Marquardt least-squares approach we searched for the source parameters of one or two rectangular dislocations with uniform slip and thanks to multiple random restarts implemented within the approach it was possible to catch the global minimum during the optimization process The second step of our modeling is represented by the linear inversion process with the computation of the nonuniform slip distribution in order to have a more accurate estimate of the slip distribution along the fault plane the linear inversion was performed by using as starting model the fault obtained from the previous nonlinear inversion discretized into 0.1 × 0.1 km2 patches and inverting the following system: where dDInSAR represents the DInSAR displacements vector G is the Green’s matrix with the point-source functions m is the vector of slip values for each patch (initially assumed as the value resulting from the nonlinear inversion) and ∇2 is a smoothing Laplacian operator weighted by an empirical coefficient k to guarantee a reliable slip varying across the fault The choice of the parameter k depends on the compromise between the data fit and the smoothness of the slip distribution We tested several values and selected k = 0.007 since appreciably higher residuals resulted for k ≥ 0.01 and similar residuals but inconsistent slip values (larger than 70 cm) with too rapidly varying slip distribution Further constraints were introduced by imposing nonnegative slip (reverse slip only) values obtained via nonlinear inversion The preferred solution is characterized by a slip distribution shallower than 1 km depth for the plane F1 the solution displays a 3 km-long two-lobed patch with maximum slip of 0.29 m located on the northern half of the fault while a maximum slip of 0.21 m results for F2 located approximately at the center of the fault We studied source directivity by using a simplified version of the directivity function Cd (ref. 27) for a bilateral linear rupture model: A value of e = 1 corresponds to a unilateral rupture whereas e = 0 corresponds to a bilateral rupture This effect can be modeled assuming that the apparent corner frequency is given by fca = fc Cd with fc indicating the actual corner frequency and fca the corner frequencies at various azimuths estimated from the source spectrum We retrieved waveforms corrected by the instrumental response at 22 stations from the Réseau Sismologique et Géodesique Français (http://seismology.resif.fr/#WelcomePlace; last accessed April 2020) (Supplementary Fig. 6A) We filtered all the waveforms in the frequency band 0.01–20 Hz we discarded the stations with a low signal-to-noise ratio which resulted to be poor at all the stations located at an elevation higher than 900 m we windowed the waveforms by cutting from 2 s before the manual S-wave picking to 6 s after We applied a 5 per cent cosine taper function and zero padding before computing the Fourier amplitude spectra The spectra were then smoothed by applying an average moving window with a four-point half width we computed the S-wave displacement spectra from the modulus of the three components velocity or acceleration spectra by dividing the spectra by 2π or 4π2 We assumed an ω−2 theoretical source spectrum model31 The computed fc as function of the station azimuth are finally fit by using the Cd function and the nonlinear Levenberg–Marquardt least-squares algorithm We used multi-temporal DSM to estimate the removed volume of rock in the Le Teil quarry so a more robust method of change detection using high-resolution topography from stereo aerial imagery is preferred the Le Teil quarry was established in 1833 and this technique is only available for the modern era distinct methods must be used for the different time periods we remark that there is a strip of images dated 1932 available from IGN but processing produced many artifacts due to scanned film’s poor preservation and noise Coregistration with 1946 data was also poor We did not use the most recent set of digital aerial images provided by IGN (dated 2013) as the poor radiometric quality of the files leads to a low quality matching over the quarry area thus rendering the dataset unusable for terrain change detection The uncertainty in the determination of the removed volume for each period is also reported) was calculated using raster statistics We considered the displacements and the stress components given the shear modulus μ and the Poisson ratio ν x3) then the displacement components in a generic point (x1 where \(R = \sqrt {\left( {x_1 - x_{01}} \right)^2\ The components of the displacement can be used to compute the strain tensor ε and the stress tensor σ in the same point (x1 Under the hypothesis of infinitesimal deformation and for isotropic medium εij = 1/2(dUi/dxj + dUj/dxi) and σij = λδijεkk + 2μεij where λ is the second Lame’s parameter and δij the Kronecker delta for the application presented in this study we used the six components of the stress tensor The photogrammetric point cloud used in this study is available in the OpenTopography repository, https://doi.org/10.5069/G9BC3WQ4, while all the other datasets generated during and/or analyzed during the current study are available in the Zenodo repository, https://doi.org/10.5281/zenodo.3973027 All the custom codes used in this study are available from the V.D.N (email: denovellis.v@irea.cnr.it) on request A Correction to this paper has been published: https://doi.org/10.1038/s43247-021-00109-7 The November 2017 MW 5.5 Pohang earthquake: a possible case of induced seismicity in South Korea Global review of human‐induced earthquakes Recommendation for the discrimination of human-related and natural seismicity Earthquakes induced by the stimulation of an enhanced geothermal system below Basel (Switzerland) Uplift and seismicity driven by groundwater depletion in central California Fault reactivation and earthquakes with magnitudes of up to MW 4.7 induced by shale‐gas hydraulic fracturing in Sichuan Basin The 2011 Lorca earthquake slip distribution controlled by groundwater crustal unloading Mechanical and statistical evidence of the causality of human-made mass shifts on the Earth’s upper crust and the occurrence of earthquakes An extremely shallow MW4.1 thrust earthquake in the eastern Sichuan Basin (China) likely triggered by unloading during infrastructure construction Notice explicative de la carte géologique de France (1/50000) Carte géologique harmonisée du département de l’Ardèche notice technique (BRGM7RP-57097-FR Bureau de Recherches Géologiques et Minières Hannouz, E. et al. Geomorphology of the cumulative deformation since Oligocene age on the Mw 4.9 Le Teil earthquake fault (South of France, 11/11/19), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20740, https://doi.org/10.5194/egusphere-egu2020-20740 (2020) The ML 5.3 Épagny (French Alps) earthquake of 1996 July 15: a long-awaited event on the Vuache Fault Analysis of central western Europe deformation using GPS and seismic data 3D GPS velocity field and its implications on the present-day post-orogenic deformation of the Western Alps and Pyrenees Ritz, J.-F., et al. The Mw4.9 Le Teil surface-rupturing earthquake in southern France: new insight on seismic hazard assessment in stable continental regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8409, https://doi.org/10.5194/egusphere-egu2020-8409 (2020) Internal deformation due to shear and tensile faults in a half-space Did (or will) fluid injection cause earthquakes Deep geothermal as resource for the future (TA-Swiss Clock advance and magnitude limitation through fault interaction: the case of the 2016 central Italy earthquake sequence Changes in groundwater level possibly encourage shallow earthquakes in central Australia: The 2016 Petermann Ranges earthquake A novel phase unwrapping method based on network programming Postseismic displacement of the 1999 Athens earthquake retrieved by the differential interferometry by synthetic aperture radar time series An accurate and efficient method for including the effects of topography in three-dimensional elastic models of ground deformation with applications to radar interferometry Radiation of seismic surface waves from finite moving sources The persistence of directivity in small earthquakes Investigating source directivity of moderate earthquakes by multiple approach: the 2013 Matese (southern Italy) MW = 5 event Tectonic stress and the spectra of seismic shear waves from earthquakes Confidence intervals for earthquake source parameters Accurate 3D comparison of complex topography with terrestrial laser scanner: application to the Rangitikei canyon (N-Z) Static stress changes and the triggering of earthquakes Stress transferred by the 1995 Mw= 6.9 Kobe shock: effect on aftershocks and future earthquake probabilities Download references Valerio for her contribution to geodetic data analysis and modeling and S Atzori for fruitful discussions on the geodetic inversion procedure This work was partially funded by the PRIN project MATISSE (Bando 2017 and the 2019-2021 IREA-CNR and Italian Civil Protection Department (DPC) agreement As for this latter and the IREA-CNR authors this paper represents the authors’ ideas and does not necessarily corresponds to the official opinion and policies of DPC Istituto per il Rilevamento Elettromagnetico dell’Ambiente Riccardo Lanari & Mario Fernando Monterroso Tobar Istituto Nazionale di Geofisica e Vulcanologia Vincenzo Convertito & Nicola Alessandro Pino performed the analyses relative to the estimate of the volume removed from the quarry; V.C performed Coulomb stress and rupture directivity analyses All the authors contributed to review the paper Peer review information Primary handling editor Joe Aslin Download citation DOI: https://doi.org/10.1038/s43247-020-00021-6 Communications Earth & Environment (2022) Communications Earth & Environment (2021) Metrics details The Original Article was published on 18 September 2020 Correction to: Communications Earth & Environment https://doi.org/10.1038/s43247-020-00021-6 but then a wrong file was used in the stress calculation the maximum Coulomb stress changes (ΔCFF) on the La Rouvière (LRf) and La Chade (LCf) faults that we had erroneously indicated as 1.10 MPa and 1.15 MPa are actually only 0.19 MPa and 0.18 MPa They are therefore almost one order of magnitude smaller than the earthquake stress drop of 1.3 MPa we conclude that the quarry activity did not induce the 2019 Le Teil earthquake The corrected Coulomb stress change estimates do support our conclusion that the earthquake was triggered by the mass removed from the quarry based on the corrected Coulomb stress changes we infer that the occurrence of the earthquake was hastened by only about 18,000 years as we had inferred from the erroneous values We would like to warmly thank Chao Liang and Jean-Paul Ampuero by checking the coherence of the stress computation with the estimated volumes Corrections have been made in both the PDF and HTML versions of the Article, and the HTML has been updated to include a corrected version of the Supplementary Information The error described above affected the original versions of Figs Which replaces the previous incorrect version: The correct version of Supplementary Fig. 10 is: The fifth sentence of the abstract originally incorrectly read “We find that almost two centuries of mass removal at a nearby cement quarry likely provided the required stress change to either induce the Le Teil earthquake or hasten its occurrence by more than 100,000 years” The correct version reads “We find that almost two centuries of mass removal at a nearby cement quarry likely provided the required stress change to hasten the occurrence of the Le Teil earthquake by more than 18,000 years” The final sentence of the second paragraph of the Introduction originally read “Nevertheless no evidence of cumulate compressional deformation has been detected along the ruptures associated with the 2019 earthquake.” In the correct version “and the geologic evidences suggest that the La Rouvière fault could have been inactive since million years” has been added to the end of this sentence The second and third sentences of the third paragraph of the Introduction originally incorrectly read “Our results indicate that the extraction activity could have induced or at least triggered the Le Teil earthquake we estimate a clock advance larger than 100,000 years.” The correct version reads “Our results indicate that the extraction activity could have triggered the Le Teil earthquake we estimate a clock advance larger than 18,000 years” The second sentence of the second paragraph in the “Stress change caused by the quarry activity” section of the Results originally incorrectly read “In particular a large patch of stress increase resulted on the northern half of the LRf while the Coulomb stress increased on most of the LCf reaching a maximum change of 1.15 MPa.” The correct version states “0.19” instead of “1.10” and “0.18” instead of “1.15” The third sentence of the same paragraph originally incorrectly read “These values are very similar to the stress drop Δσ = 1.3 MPa estimated for the 2019 earthquake (see “Methods” section).” The correct version now states “less than one order of magnitude smaller than” instead of “very similar to” The eighth sentence of the first paragraph of the Discussion originally incorrectly read “The estimated cumulative maximum Coulomb stress change on the fault due to the total mass subtraction is 1.10 MPa by 2011 corresponding to maximum normal Δσn = 0.87 MPa and shear stress Δτ = 0.67 MPa.” The correct version states “0.19” The first sentence of the second paragraph of the Discussion originally incorrectly read “The shear stress value resulting from the quarry activity is comparable with the stress drop of the earthquake (~1 MPa) pointing to an anthropogenic origin of the seismic event.” The correct version reads “The shear stress value resulting from the quarry activity is one order of magnitude larger than what typically considered sufficient to trigger an earthquake (0.01 MPa) pointing to an anthropogenic effect on the origin of the seismic event” The second sentence of the second paragraph of the Discussion originally incorrectly read “In fact these results allow stating that the rock extraction from the quarry likely have induced the 2019 Le Teil earthquake or triggered it by dramatically accelerating the loading of the fault and hastening its unlocking.” In the correct version “induced” has been replaced with “triggered” and “or The third sentence of the second paragraph of the Discussion originally incorrectly read “Incidentally we note that even considering the upper extreme for the stress drop (Δτ = 2.0 MPa it would be of the same order of magnitude of the calculated shear stress change and the hypothesis of an anthropogenic origin for the earthquake is still strongly supported.” The correct version reads “Incidentally we note that even considering the upper extreme for the stress drop (Δτ=2.0 MPa this would not change our conclusion and the hypothesis of an anthropogenic effect on the origin for the earthquake still holds.” The first sentence of the third paragraph of the Discussion originally incorrectly read “In case of triggering the time advance can be estimated by dividing the cumulative stress change associated with the quarry activity by the tectonic stress rate” In the correct version “In case of triggering,” has been removed from the start of this sentence The second sentence of the third paragraph of the Discussion originally incorrectly read “About 111,000 years is the time required for the tectonic forces to load on the fault a stress amount similar to the change produced by ~180 years of rock extraction from the quarry (Fig The correct version states “18,000” instead of “111,000” The fourth sentence of the third paragraph of the Discussion originally incorrectly read “Assuming for 2011–2019 the same average extraction rate calculated for the period 2007–2011 (and the same location) the total normal and shear stress change would be Δσn = 1.3 MPa and Δτ = 1.0 MPa corresponding to a time advance of ~1.6 × 105 years making the induction hypothesis even more realistic in agreement with the geologic evidences suggesting that the LRf could have been inactive since million years.” In the correct version “1.3” “1.0” and “1.6 x 105” have been replaced with “0.26” “induction” has been replaced with “triggering” and “in agreement with the geologic evidences suggesting that the LRf could have been inactive since million years” has been removed from the end of the sentence The second sentence of the fifth paragraph of the Discussion originally incorrectly read “In the hypothesis of a linear increase of the fault strength with depth and especially if on deeper portions of the fault there is near-critical preexisting tectonic stress 2019.” In the correct version “these” has been replaced with “this” and “of a linear increase of the fault strength with depth” has been removed The third sentence of the fifth paragraph of the “Calculation of the rock volume extracted from the quarry” section of the Methods originally incorrectly read “Original DSM raster files were clipped and resampled into a common pixel size (3 m for 1833–1946 and 2 m for the rest) and then converted into point clouds.” In the correct version “for 1833–1946 and 2 m for the rest” has been removed The original version of this Article contained an error in Ref which contained an incorrect spelling of the first author’s name as: 4 originally incorrectly stated “The increment of the shear stress on the faults of the 2019 earthquake caused by the tectonic forces (blue line; exaggerated vertical scale) starting from the previous (unknown) earthquake and by the Le Teil quarry activity (1 MPa; gray line).” The correct version states “0.19” instead of “1” The values in the fourth column of Supplementary Table 4 titled “ΔCFF* (MPa)” originally read “0.14” In the correct version these values are replaced by “0.02” The caption of Supplementary Table 4 originally incorrectly read “* ΔCFF is computed at the point indicated in Supplementary Fig. 9”. The correct version states “Supplementary Fig. 10” instead of “Supplementary Fig Download citation DOI: https://doi.org/10.1038/s43247-021-00109-7 Metrics details When an earthquake in southern France caused the ground to rupture—a phenomenon not known during the last 25 years in the region—the earthquake science community worked together to determine the implications for hazard assessment Now we must maintain that spirit of co-operation for the future The equipment is a laser scanner to image accurately the offset unaccustomed to such destructive earthquakes in metropolitan France joined the conversation Field geologists have continued to investigate where possible despite the lockdowns and curfews resulting from the COVID-19 pandemic and the motivation of our group has remained strong we were able to excavate a dozen paleoseismological trenches that demonstrate earlier incidences of ground rupture Some trenches are still open for 2021/2022 scientific conferences field trips and for teaching: they are a crucial resource in a country were such events and research opportunities are not so common All this was made possible thanks to the positive and enthusiastic response of land owners a welcome behavioral trait in freshly earthquake-shaken areas We have adapted our way of working to meet pandemic-related health requirements We also had to satisfy the needs of co-working: we concentrated field efforts as well as external media visits when restrictions allowed and moved online conferences to exchange ideas to the phases of lockdown we found that these adaptations allowed us to continue to carry out our time-sensitive work effectively Our own careers and personal trajectories have been affected as well as those of our colleagues The Le Teil earthquake has turned the research community’s attention and activity to seismic hazard and seismicity in intraplate areas and particularly in France A few fundamental scientific questions now need to be addressed This is from the first trench out of a dozen that was dug during the 2020 spring; notice the fracture in the colluvium related to a pre-historical activity and has only now erupted onto the French scene If other sensitive sites are threatened by earthquake-related surface ruptures we need to identify and mitigate these risks Geological and paleoseismological data—the only data that can provide long-term constraints on the timing of tectonic deformation—will be essential for gaining a clearer picture of the responsible driving forces Substantial media coverage of the earthquake and its impact put us and our colleagues in the spotlight following the publication in Communications Earth & Environment We had media interest from national television and radio reports and live broadcasts on the anniversary of the earthquake Public and scientific interest in seismic risk has thus been revived and the acquisition of the data necessary to inform seismic risk requires long-term commitment and we must remain determined to ensure that this initial impetus is maintained in the years to come Exceptional ground motion during the shallow Mw 4.9 2019 Le Teil earthquake Rapid response to the M w 4.9 earthquake of November 11 Constraining the point source parameters of the 11 November 2019 Mw 4.9 Le Teil earthquake using multiple relocation approaches Insights on fault reactivation during the 2019 November 11 Mw 4.9 Le Teil earthquake in southeastern France Vallage, A. et al. Multitechnology characterization of an unusual surface rupturing intraplate earthquake: the M L 5.4 2019 Le Teil event in France. Geophys. J. Int. 226, 803–813, https://doi.org/10.1093/gji/ggab136 (2021) New perspectives in studying active faults in metropolitan France: the “Active faults France” (FACT/ATS) research axis from the Resif-Epos consortium A Worldwide and Unified Database of Surface Ruptures (SURE) for Fault Displacement Hazard Analyses Probability of Occurrence and Displacement Regression of Distributed Surface Rupturing for Reverse Earthquakes Sarmiento, A. et al. Fault Displacement Hazard Initiative Database. Report GIRS-2021-08. UCLA Natural Hazards Risk And Resiliency Research Center https://doi.org/10.34948/N36P48 (2021) Probabilistic Fault Displacement Hazard Assessment (PFDHA) for Nuclear Installations According to IAEA Safety Standards Present-day geodynamics of the Western Alps: new insights from earthquake mechanisms Author Correction: Coincident locations of rupture nucleation during the 2019 Le Teil earthquake Liang, C. & Ampuero, J.-P. Comment on “Coincident locations of rupture nucleation during the 2019 Le Teil earthquake, France and maximum stress change from local cement quarrying” by De Novellis et al. (preprint). Geophysics https://doi.org/10.1002/essoar.10504400.2 (2020) Processes and deformation rates generating seismicity in metropolitan France and conterminous Western Europe The Transversal Seismicity Action RESIF: A Tool to Improve the Distribution of the French Seismicity Products Download references Institut de Radioprotection et Sûreté Nucléaire contributed equally to the conceptualization Download citation DOI: https://doi.org/10.1038/s43247-022-00392-y An earthquake that struck a remote part of southern France last Monday has scientists scratching their heads First, the 4.8 magnitude quake was unusually large for France, which sees plenty of smaller temblors seismologist Jean-Paul Ampuero of the Université Côte d'Azur told National Geographic the earthquake near the small town of Le Teil ruptured the Earth's surface it’s a big opportunity to learn something new,” Ampuero said The earthquake, which was moderate by global standards, struck shortly before noon local time on Nov. 11 near Le Teil, about 90 miles northwest of Marseille, the Associated Press reported. One person was seriously injured. About 200 homes were severely damaged and researchers are trying to learn its source France does not sit on top of a tectonic plate boundary So big earthquakes like those that happen when the San Andreas fault slips are rare in France a geodesist at the Institut de Physique du Globe de Paris Moderate and major quakes also usually occur deep under the surface The Le Teil quake appears to have happened just a mile or so underground One potential source for the shallow moderate quake is work at a nearby quarry Robin Lacassin of the Institut de Physique du Globe de Paris wrote on Twitter that removing rocks in the quarry would reduce normal stress and cause the fault to rupture We recognize our responsibility to use data and technology for good We may use or share your data with our data vendors The Weather Channel is the world's most accurate forecaster according to ForecastWatch, Global and Regional Weather Forecast Accuracy Overview First, the 4.8 magnitude quake was unusually large for France, which sees plenty of smaller temblors seismologist Jean-Paul Ampuero of the Université Côte d'Azur told National Geographic the earthquake near the small town of Le Teil ruptured the Earth's surface it’s a big opportunity to learn something new,” Ampuero said The earthquake, which was moderate by global standards, struck shortly before noon local time on Nov. 11 near Le Teil, about 90 miles northwest of Marseille, the Associated Press reported. One person was seriously injured. About 200 homes were severely damaged even for global standards,” Ampuero said Robin Lacassin of the Institut de Physique du Globe de Paris wrote on Twitter that removing rocks in the quarry would reduce normal stress and cause the fault to rupture The sur­face of the Earth is divid­ed into dif­fer­ent tec­ton­ic plates, upon which the oceans and con­ti­nents rest. Over time these plates move, slide, col­lide or over­lap with on anoth­er. Where the bound­aries of the plates become deformed, pres­sure often builds up to the point that is sud­den­ly released by a sud­den slip along the faults – this is the well under­stood ori­gin of earth­quakes1 towards the inte­ri­or of tec­ton­ic plates far from the agi­ta­tion of plate bound­aries in areas that are sup­posed to be calm and free of defor­ma­tion some unex­pect­ed earth­quakes have been occur­ring They have raised ques­tions in the field seis­mol­o­gy where sci­en­tists have pro­posed new the­o­ries to explain the ori­gin of these earth­quakes flu­id cir­cu­la­tion or melt­ing glac­i­ers are thought to be triggers… an earth­quake of mag­ni­tude 4.9 in the Rhone val­ley sur­prised the sci­en­tif­ic com­mu­ni­ty the seis­mic­i­ty record­ed was rel­a­tive­ly low: 39 earth­quakes were mea­sured between 1962 and 2018 in this area all of low mag­ni­tude (less than 3),” explains Jean-François Ritz The fault at the ori­gin of this earth­quake was not iden­ti­fied as an active fault either – mean­ing one with the poten­tial to gen­er­ate earth­quakes It seemed to have been qui­et for 20 mil­lion years “Intraplate earth­quakes can reach sig­nif­i­cant mag­ni­tudes, but they are much rar­er than those locat­ed at plate bound­aries,” explains Éric Calais. Since the first seis­mic record­ings were made in 1974, only about twen­ty major intraplate earth­quakes (of mag­ni­tude 6 or more) have been record­ed through­out the world3 Old­er earth­quakes are known from his­tor­i­cal archives or from traces left in the geo­log­i­cal land­scape the same earth­quake tends to be repeat­ed at a vari­able fre­quen­cy for exam­ple a few hun­dred years in Cal­i­for­nia,” con­tin­ues Éric Calais This repet­i­tive behav­iour is not observed for intraplate earth­quakes: some seem to be ‘orphan’ earth­quakes on faults that have been inac­tive for mil­lions of years A bet­ter under­stand­ing of these earth­quakes is essen­tial: their mod­er­ate to high mag­ni­tude makes them poten­tial­ly very destruc­tive. They affect regions that are often poor­ly pre­pared and can be trig­gered at very shal­low depths. The Le Teil earth­quake – which occurred less than 20 kilo­me­tres from two nuclear pow­er plants – was trig­gered only 1 km under­ground4 and caused an eco­nom­ic loss of sev­er­al mil­lion euros.  a reg­u­la­to­ry zon­ing sys­tem impos­es earth­quake-resis­tant con­struc­tion stan­dards for build­ings But it is based on the nation­al seis­mic haz­ard map in which unex­pect­ed earth­quakes like the Le Teil earth­quake are not iden­ti­fied the sci­en­tif­ic com­mu­ni­ty has become aware that intraplate earth­quakes can occur in unex­pect­ed places and that the tec­ton­ic mod­els on which con­ven­tion­al seis­mic haz­ard cal­cu­la­tions are based do not allow this risk to be reflect­ed,” says Éric Calais Intraplate earth­quakes can occur in unex­pect­ed places and clas­si­cal tec­ton­ic mod­els do not allow this risk to be reflected it is clear that its mag­ni­tude is explained by tec­ton­ic forces The fact remains that intraplate earth­quakes are few so it is dif­fi­cult to quan­ti­fy their behav­iour Researchers repro­duce them in numer­i­cal sim­u­la­tions but it is com­pli­cat­ed to clear­ly iden­ti­fy the role of each phe­nom­e­non (plate tec­ton­ics it is very com­pli­cat­ed to cal­cu­late future risks espe­cial­ly as they can some­times only occur once in a giv­en loca­tion We lack objec­tive indi­ca­tors to assess future intraplate seismicity.  work is con­tin­u­ing around the Le Teil earth­quake in search of traces of past earth­quakes “We can rea­son­ably assume that the fault where this earth­quake was trig­gered will remain calm for some time but oth­er faults exist in the area,” con­cludes Jean-François Ritz “I have no doubt that a reassess­ment of the region­al seis­mic haz­ard will be car­ried out in a few years’ time we need to launch a lot more research and obser­va­tions in this area and review our ideas!” Director of the Laboratory for Bio-Inspired Chemistry and Ecological Innovations President of the Foundation for Research on Biodiversity and Professor at Muséum National d'Histoire Naturelle CNRS Research Director at the Dynamic Meteorology Laboratory (LMD) and Professor at Ecole Polytechnique (IP Paris) Head of economics department at the Institut Polytechnique de Paris and Best young French economist 2020 You don't have permission to access the page you requested What is this page?The website you are visiting is protected.For security reasons this page cannot be displayed Here's whySomething very weird is happening to the planet's earthquakes Here's whyEarth-shattering seismic events can occur away from the fault lines between tectonic plates And there’s no easy way to predict when or where they’ll hit When it comes to earthquakes, always expect the unexpected. That’s the message coming from seismologists Prof Éric Calais, of the École Normale Supérieure (ENS) in Paris, and Jean François Ritz Director of Montpellier’s CNRS Laboratoire Géosciences Underpinning their advice is the reality that Earth sometimes shakes in places it shouldn’t happen far from the active margins of tectonic plates and in places that are otherwise geologically quiet Gaining a better understanding of them and an explanation for them has become the mission of the French scientists outer carapace of our world are performing a slow dance across the face of the planet moving at about the same rate that a person’s fingernails grow While nearly all the geological action worth talking about takes place where the tectonic plates meet occurring in the interiors of the plates far from the margins reasons for Calais and Ritz to want to shed more light on them Intraplate quakes are rare: the number of significant shakes is tiny compared to what happens at the edges of the plates with Calais noting that only 20 of a magnitude of 6 and above have been recorded since 1974 That’s less than half of one per cent of the number of similarly sized quakes at plate margins over the same time yet they’re capable of causing immense destruction in unprepared urban centres that never regarded quakes as a problem Intraplate earthquakes can happen anywhere that a geological fault is present in the crust they’ve been recorded as far apart as Basel in Switzerland they’ve caused substantial damage in the Australian city of Newcastle and in the southern African country of Botswana and Puebla the latter resulting in close to 400 deaths Calais and Ritz draw attention to a magnitude 5 earthquake that happened close to the Rhône Valley village of Le Teil in 2019 while in 2008 a magnitude 5.2 event beneath the Lincolnshire town of Market Rasen rocked much of England What a local newspaper referred to as “The Great Rasen Earthquake” injured one person and caused damage estimated at around £20 million While the tremors that strike the UK and France tend to be small this is far from the case in other parts of the world In 2001, the most devastating intraplate quake of modern times – a magnitude 7.6 event that struck Bhuj in the Indian state of Gujarat – destroyed an estimated 300,000 buildings and claimed up to 20,000 lives a quake of magnitude 7 (or thereabouts) hit the US east-coast city of Charleston in 1886 killing 60 people and inflicting widespread damage A little over 80 years earlier and around 1,200km (approx 765 miles) to the west three powerful intraplate quakes struck in the New Madrid region of Missouri from December 1811 to February 1812 these resulted in violent tremors across an area almost three times the size of those that hit the UK and 10 times larger than those associated with the great San Francisco earthquake of 1906 As the region at the time was sparsely populated the overall impact was not as devastating as it could have been cities far from a plate boundary are at risk from large The latter is of particular interest: on 18 October 1356 a series of violent intraplate quakes – the largest being a magnitude of 6.6 – and the fire that followed Despite being one of the largest recorded quakes in central Europe the human toll was smaller than could be expected as the population of Basel was only about 6,000 and many had already fled when the main event happened due to a powerful foreshock earlier in the day One thing that both intraplate earthquakes and those at the plate margins have in common is their operating mechanism strain accumulates over time on a geological fault – a weakness in the Earth’s crust – until it reaches a critical level that causes the fault to break or rupture This is what causes a quake: the rupture releasing energy in the form of seismic waves so as to reduce the strain to zero Strain can accumulate along the great geological faults that mark the contacts between individual plates and – based on the average return period of past quakes on a fault – rough estimates can be made about when the next is likely to happen Calais observes that the frequency in California is typically a couple of hundred years In relation to faults that host intraplate quakes Such structures are often old and deeply buried and on occasion their existence isn’t suspected at all until after they’ve hosted an earthquake The absence of any record of past events makes it impossible to estimate when the next one might happen some intraplate quakes might even be so-called ‘orphan’ events that aren’t part of a series and which involve the one-off reactivation of an ancient fault that hasn’t ruptured for millions of years While the mechanism of strain accumulation and release is the same for both intraplate quakes and those that happen at plate boundaries the triggers that cause rupture may well be different Fault rupture at the edges is provoked by plate movement but Calais and Ritz propose something different for the plate interiors: discrete triggers that occur rapidly These can include unloading due to the melting of ice sheets or surface erosion; rainfall seeping down from the surface; or fluids working their way up from the Earth’s mantle Mining and the filling of new reservoirs have been linked to intraplate seismicity the atmospheric pressure fall that arises from the passage of a tropical cyclone it’s worth noting that a fault that’s primed and ready to rupture can be induced to do so by pressure equivalent to that of a handshake while it may have taken millions of years for strain to accumulate on an ancient intraplate fault setting it off can happen over a relatively short period of time Calais and Ritz have zeroed-in on the aforementioned 2019 Le Teil quake and come to the conclusion that it was probably triggered by an unloading of the crust above following the melting of glaciers in the region at the end of the ice age perhaps aided and abetted by nearby quarrying In fact, unloading and deformation of the crust due to the rapid melting of the great ice sheets between about 20,000 and 10,000 years ago has been implicated in the promotion of many intraplate quakes Norway and Sweden experienced an earthquake ‘storm’ as a result of the rapid melting of the 3km-thick (1.9-mile) Scandinavian Ice Sheet which unloaded intraplate faults beneath and allowed them to release the strain that had been accumulating over tens of thousands of years The result was a number of colossal magnitude 8 quakes one of which – around 8,200 years ago – triggered a giant submarine landslide off the coast of Norway that launched a tsunami into the North Atlantic The waves reached heights of 20m (65ft) across Shetland and 6m (20ft) on the east coast of Scotland Calais highlights the difficulty of predicting intraplate quakes it’s very complicated to calculate future risks especially as they can sometimes only occur once in a given location,” he says “We lack objective indicators to assess future intraplate seismicity” studies have been undertaken that focus on the threat posed by intraplate quakes in areas that have been affected by them in the past Today, more than half the world’s population is urbanised and cities in areas affected by intraplate quakes have grown considerably in size is now the second largest urban centre in Switzerland hosting a population of around half a million people and the city is a major centre for banking and the chemical industry The consequences of a quake similar to that of 1356 would be far more serious. According to the Swiss Seismological Service, this would result in 3,000 deaths and up to 80,000 buildings suffering moderate to very severe damage Charleston is now an urban centre of more than three quarters of a million people mostly living in masonry or concrete buildings rather than wooden as at the time of the 1886 earthquake That means any comparable event would be both far more destructive and deadly. Even worse, a 2009 study funded by the US Federal Emergency Management Agency (FEMA) predicted that, were there to be a magnitude 7.7 quake in the vicinity of the early 19th century events in New Madrid, the impact would be felt across eight states, with Missouri and Tennessee the hardest hit The major urban centres of Memphis and St Louis would be the most severely affected leading – the study estimated – to more than 700,000 damaged buildings 3,500 deaths and the displacement of more than 7 million people New York is far from safe from a future quake having an estimated return period of 3,400 years means that an intraplate quake is extremely rare there’s no requirement for buildings to be able to stand up to the shaking arising from a quake of that size hundreds of thousands of buildings would be destroyed or damaged But much smaller events could also significantly impact a city that’s poorly prepared comparable to one that struck New York in 1884 and expected every hundred years or so could be lethal and result in a repair bill adding up to billions of dollars When it comes to future intraplate earthquakes there’s one other major factor to consider: global heating the reduced load on the crust beneath is leading to faults releasing long-accumulated strain where a vertical kilometre of ice (0.6 miles) has been lost in some areas the ice sheet shed more than half a trillion tonnes of ice to flood the whole of the UK to a depth of 2.5m (8ft) The crust beneath is uplifting as a consequence and an eventual hike in intraplate quake activity has been predicted the potential for such quakes to trigger submarine landslides capable of generating tsunamis means that everyone living around the margins of the North Atlantic should take note Could it be that we’re facing a shakier future A 4.8 magnitude earthquake struck southeast France on November 11 damaging buildings and injuring four people The small town of Le Teil suffered some of the worse damage with hundreds of structures cracked and crumbling such as the one pictured here in the town's Rouviere quarter An uncommonly shallow temblor rattled the country sending scientists buzzing as they began hunting down its source Clément Bastie and his family were preparing dinner in the small French town of Le Teil when the walls began to tremble Then a booming sound reverberated through the town Fears of explosions at the nearby nuclear energy plant flooded into his mind rushed outside expecting to see the bloom of a mushroom cloud the shaking came from something less devastating but still surprising for the region: an earthquake that cracked through the ground Monday’s event was only of moderate intensity by global measures but it was a “very large one for French standards,” he says Even more surprising is that the temblor cut clean to the surface, cracking Earth’s crust like an eggshell. Such breaks are common for hefty earthquakes, such as the 7.2 magnitude Landers earthquake that struck California in 1992 The formation of a surface fracture during the Le Teil temblor therefore left researchers scratching their heads prompting a hunt for the curious quake’s source By studying the region’s past and current geodynamics scientists hope to find clues as to what sparked this event and what it can reveal broadly about the mechanics of our quaking planet it’s a big opportunity to learn something new,” Ampuero says Earthquakes worldwide come from the slow-motion dance of the planet’s tectonic plates These blocks of crust and upper mantle are continually jostling for position which builds up stresses until eventually the ground breaks sending out ripples of waves that we feel as quakes France’s tectonics are particularly complicated. The country sits atop the Eurasian tectonic plate, which abuts the African plate to the south. But the boundary between the two is complex, and it includes a number of smaller plate fragments known as microplates The varying movements as these blocks of Earth collide squishes France from multiple directions “We don't have [a] large, simple, nicely defined strike-slip fault like the San Andreas fault,” geophysicist Lucile Bruhat from the Ecole Normale Supérieure in Paris says via Twitter direct message mega-temblors like those in California are more rare What’s more, moderate ruptures in any location don’t usually fracture the surface, explains Raphaël Grandin Grandin didn’t expect to see any features atop the ground a clear signal emerged revealing signs of not only land deformation Most larger earthquakes start far below the surface radiating from a break in the plates at least three to six miles down But analysis suggests that this latest temblor unzipped the crust starting a mere mile or so underground which means that the stresses are lower and earthquakes are usually weaker Faults also behave differently at different depths While deep stress frequently releases with a jolt “They tend to creep; they don’t tend to break,” he says Such events aren’t without precedent; Grandin points to a shallow 4.7 magnitude temblor that left a crack in Australia and how France’s quake was both moderate and shallow remains an open question researchers headed to the field on November 13 using the satellite analyses to help pinpoint the crack as it jutted across roads they’re working to study the site in many ways including installing seismometers to track the fault’s activity and recording any additional signs of deformation Ampuero and his team also collected a fresh rock they located near the fault and plan to test its properties in the lab to see if there’s anything weird that might explain the unusual break Other scientists are now studying older satellite images of the region to suss out any past deformation that might offer more clues to the temblor’s source Perhaps no one is more intrigued by the odd event than Bastie, who lives less than half a mile from an obvious segment of the fracture, which he joined the scientists on Wednesday to explore. “These clues of the Earth’s activity, I just saw it in books ... I never experienced it in the field,” he says. “It was both scary and exciting.” Ampuero and his colleagues are investigating this possibility."},"type":"p","style":{}},{"id":"html22","cntnt":{"mrkup":"Perhaps no one is more intrigued by the odd event than Bastie who lives less than half a mile from an obvious segment of the fracture which he joined the scientists on Wednesday to explore."},"type":"p","style":{}},{"id":"html23","cntnt":{"mrkup":"“These clues of the Earth’s activity I never experienced it in the field,” he says “It was both scary and exciting.”"},"type":"p","style":{}}],"cid":"drn:src:natgeo:unison::prod:e2fadc20-7281-4508-9c21-89a50e9ffec5","cntrbGrp":[{"contributors":[{"displayName":"Maya Wei-Haas"}],"title":"By","rl":"Writer"}],"mode":"richtext","dscrptn":"An uncommonly shallow temblor rattled the country sending scientists buzzing as they began hunting down its source.","enableAds":true,"endbug":true,"isMetered":false,"isUserAuthed":false,"isTruncated":false,"isEntitled":false,"freemiumContentGatingEnabled":true,"premiumContentGatingEnabled":false,"ldMda":{"cmsType":"image","hasCopyright":true,"id":"5d09a5b0-d5e1-4fd5-a588-9cbc72c03e6d","lines":3,"positionMetaBottom":true,"showMore":true,"caption":"A 4.8 magnitude earthquake struck southeast France on November 11 Geophysicist Zachary Ross is pioneering a new way to understand the world beneath our feet Europe: Holcim has secured funding for three separate carbon capture utilisation and storage (CCUS) projects at its cement plants in Europe The recipient projects are the Go4Zero project at Holcim Belgium's Obourg cement plant in Belgium the KOdeCO project at Holcim Croatia's Koromačno cement plant in Croatia and the eM-Rhône project at Lafarge Ciments' Le Teil cement plant in France The Le Teil plant's system will be used to produce e-methanol while the investment at the Koromačno plant will be part of a package of upgrades to turn the plant carbon neutral Alongside on-going projects in Germany and Poland this will bring Holcim's total number of EU-funded CCUS projects to five Holcim is committed to US$2.33bn-worth of investments of its own in over 50 carbon capture projects worldwide before 2030 Holcim's Europe regional head Miljan Gutovic said “It’s exciting to be at the forefront of decarbonising the building sector in Europe The support we are receiving from the EU Innovation Fund for five of our CCUS projects is a great testament to the strength of our engineering teams the maturity of our technologies and our advanced partnerships across the value chain Our robust pipeline of projects positions us as the partner of choice to scale up carbon capture technologies in Europe.” Vous utilisez un ancien navigateur. Ce site risque de ne pas s'afficher correctement. Mettez à jour votre navigateur pour améliorer votre expérience Confortement d’une maison endommagée par le séisme du Teil (commune de Viviers Le Teil is an average-sized municipality (8,700 inhabitants) which was very heavily affected by the earthquake of 11 November 2019 (850 decrees prohibiting access to around 2,700 buildings in the municipality) Observing the process implemented to enable a return to normal life in Le Teil (the municipality that was the most affected by the earthquake) will teach us valuable lessons on how to improve resilience to seismic risks in various regions BRGM suggested setting up a system to monitor and observe the reconstruction phase following the November 2019 earthquake The observations were to primarily focus on the municipality of Le Teil The aim was to start collecting data and provide regular updates over subsequent years in order to obtain a detailed analysis of the reconstruction operations across the municipality This analysis will ultimately enable us to identify the factors that have a positive or negative impact on an area's resilience to seismic risks at national level (for continental France) valuable field data were collected concerning the extent of damage to buildings thanks to the deployment of the AFPS's "Emergency" plan The post-seismic mission conducted by the AFPS also collected important information concerning the various stakeholders involved and the recovery strategies the municipality was able to begin its reconstruction notably drawing on the institutional framework of a Partnership-based Development Plan (PPA) to coordinate the stakeholders involved and the various actions that will not only contribute to helping the area recover from the catastrophe the earthquake affected an area that was already vulnerable from a socio-economic standpoint and the municipality was already looking at potential urban renovation projects The PPA will bring together all the stakeholders and establish a certain strategic continuity in terms of urban planning while also drawing on the reconstruction operations to accelerate the municipality's urban transformation The creation of an observatory to monitor and analyse the reconstruction process underscores the actions and milestones proposed in the PPA plan Detailed information has been collected concerning the buildings in the municipality in order to quantify the extent of the damage and how it evolves over time A reference base of the building stock has been established to determine the total number of buildings and their main characteristics as regards the organisation and coordination of the various players involved in the reconstruction the work carried out in 2021 highlighted the crucial role of insurance experts in the process and also provided a clearer picture and appreciation of the institutional context notably with a view to identifying the administrative and urban planning tools used in the reconstruction and measuring how the process is perceived by the local population The actions carried out will also demonstrate the effectiveness of quantitative tools used to observe the reconstruction (assessment of changes to the area's vulnerability based on the works carried out) The campaign will continue over the next few years particularly in order to ensure annual updates of data through field visits and local consultations and to monitor the changes in the indicators Subscribe to our newsletter and receive our news every month The Local Europe ABVästmannagatan 43113 25 StockholmSweden Please log in here to leave a comment France: Holcim has committed €200m over the past three years to decarbonise its French manufacturing sites This initiative is part of a roadmap signed with the French government in November 2023 aiming to reduce CO₂ emissions by over 50% by 2030 and 95% by 2050 compared to 2015 levels At the 7th Choose France summit on 13 May 2024 Holcim announced an additional investment of €64m for developing new technological and industrial platforms across its seven French plants located in Saint-Pierre-la-Cour set to be operational between 2025 and 2026 will focus on CO₂ capture technology (€9m at Martres Tolosane) integration of construction waste in cement processes (€24m across all plants) and the use of biomass waste fuels (€13m at Saint-Pierre-la-Cour An additional €6m will be allocated to recycling and transformation platforms for construction waste in five urban areas: Laval These investments are expected to reduce Holcim's CO₂ emissions in France by over 120,000t/yr and create more than 40 jobs Your Ads Privacy ChoicesIMDb France (Reuters) – Kazakh Alexey Lutsenko claimed his maiden victory on the Tour de France when he won the sixth stage a 191-km trek from Le Teil on Thursday as the top guns again delayed the fight for the general classification prevailed from an eight-man breakaway at the top of Mont Aigoual to add to his 2017 Vuelta stage win 55 seconds behind with Belgian Greg van Avermaet in third Briton Adam Yates retained the overall leader’s yellow jersey after staying tucked in the main peloton which crossed the line with a deficit of 2:53 “We talked about it in the team bus this morning and we agreed that it was a stage that suited me,” said Lutsenko who broke clear in the punishing ascent to the Col de la Lusette a 11.7km climb at an average gradient of 7.3% the main favourites did not use the ascent to test each other leaving defending champion Egan Bernal’s Ineos team to set a moderate pace I think we climbed at our own speed and saved energy we just tried to stay safe,” said Ineos domestique Michal Kwiatkowski “Everyone is keeping their powder dry and is saving energy for the next days,” said Yates who was never threatened throughout the stage suffered an untimely puncture in the climb up to the Col de la Lusette but managed to regain his place in the peloton easily when Frenchman Julian Alaphilippe produced a brief attack to regain one second after losing the yellow jersey to Yates following a 20-second penalty for illegal feeding on Wednesday Friday’s seventh stage is a 168-km ride from Millau to Lavaur which is expected to favour the sprint specialists Powered by PageSuite   France-- Kazakh Alexey Lutsenko claimed his maiden victory on the Tour de France when he won the sixth stage Briton Adam Yates retained the overall leader's yellow jersey after staying tucked in the main peloton "We talked about it in the team bus this morning and we agreed that it was a stage that suited me," said Lutsenko leaving defending champion Egan Bernal's Ineos team to set a moderate pace we just tried to stay safe," said Ineos domestique Michal Kwiatkowski "Everyone is keeping their powder dry and is saving energy for the next days," said Yates The only sparkle came in the final metres Friday's seventh stage is a 168-km ride from Millau to Lavaur Copyright © 2020 All copyrights on articles and/or content of The Caribbean Herald N.V. dba The 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