Volume 9 - 2021 | https://doi.org/10.3389/feart.2021.629736 This article is part of the Research TopicSource and Effects of Light to Moderate Magnitude EarthquakesView all 13 articles Ischia is a densely inhabited and touristic volcanic island located in the northern sector of the Gulf of Naples (Italy) the Mw 3.9 Casamicciola earthquake occurred after more than one century of seismic quiescence characterized only by minor seismicity which followed a century with three destructive earthquakes (in 1828 despite their moderate magnitude (Mw < 5.5) lead to dreadful effects on buildings and population an integrated catalogue systematically covering historical and instrumental seismicity of Ischia has been still lacking since many years we review and systematically re-analyse all the available data on the historical and instrumental seismicity to build an integrated earthquake catalogue for Ischia with a robust characterization of existing uncertainties Supported by new or updated macroseismic datasets we significantly enriched existing catalogues as the Italian Parametric Earthquake Catalogue (CPTI15) that passed from 12 to 57 earthquakes with macroseismic parametrization We also extended back by 6 years the coverage of the instrumental catalogue homogenizing the estimated seismic parameters The obtained catalogue will not only represent a solid base for future local hazard quantifications but also it provides the unique opportunity of characterizing the evolution of the Ischia seismicity over centuries and magnitude distributions of Ischia seismicity also in the present long-lasting period of volcanic quiescence is significantly non-stationary and characterized by a b-value larger than 1 The characterization of the seismic activity and of the consequent hazard is largely based on the knowledge that we can gain from past activity To allow a robust characterization of the seismicity such catalogues should systematically collect all the known seismic events as well as characterize at best the completeness of the record in the different periods and the existing uncertainty about seismic parametrization Especially for historical times and for light to moderate magnitudes (M < 6) Ischia and the Neapolitan volcanic district (A) Location of the Neapolitan volcanic district and of Vesuvius (B) Map of the island of Ischia and its present-day seismic network of the Island of Ischia and Procida considering that this small island (less than 50 km2) is densely inhabited with more than 60,000 steady inhabitants incremented by tourists during the summer season the existence of long periods of seismic quiescence with very low seismicity rates and of sequences of destructive earthquakes such as the one that occurred in the XIX century shows the complexity of the processes that generate the earthquakes at Ischia with duration magnitude estimations (Md) incompatible to CPTI15 inappropriate to characterize the seismicity of Ischia due to the very low number of events reported as well as earthquake parameters not directly comparable to each other and uniform through time we systematically revise the historical and instrumental seismicity in order to produce the first integrated catalogue of the earthquakes that can be attributed to the local volcano-tectonic activity of Ischia The analysis of the historical macroseismic records (Section “Macroseismic Catalogue: 8th Century BC – 2019”) consisted of: (i) scrutinizing the literature data to include all the earthquakes caused by local sources in the island; (ii) homogenizing intensity data; (iii) re-parametrizing the collected data with a standardized procedure that takes into account the relevant uncertainty; (iv) evaluating the completeness of the catalogue from the historical standpoint As for the recent instrumental seismicity (Section “Instrumental Catalogue: 1993–2019”) we: (i) discuss the evolution of the local instrumental network; (ii) revise the data and the parameter estimations extending the analysis as far back as the 1990s; (iii) evaluate the completeness of the catalogue The resulting integrated catalogue (macroseismic plus instrumental records) is then statistically analysed (Section “Statistical Characterization of the Seismicity”) through: (i) the characterization of the frequency-size distribution and related uncertainty; (ii) the characterization of the occurrence model of the seismicity by testing the hypothesis of stationarity in time utilizing a statistical test; and iii) the characterization of the spatial distribution and related uncertainty The result is an earthquake catalogue spanning over ten centuries which represents the primary dataset for investigating the long-term behaviour of the volcano seismicity of Ischia and assessing the related seismic hazard at local scale we describe the procedure adopted to produce the new revised macroseismic catalogue for Ischia through three main steps: (i) producing a comprehensive inventory of the known earthquakes; (ii) homogenising geographically the macroseismic intensity data; and (iii) parametrizing with a standardized procedure the events to determine their magnitude and location The revised catalogue, covering the time-span from the 8th century BC to 2019, is reported as Supplementary Dataset 1 We collected all the information available in the literature into a comprehensive inventory. The starting point is represented by the events included in the Italian Archive of Historical Earthquake Data (hereinafter ASMI;2 Rovida et al., 2017) – the basic tool for collecting and validating macroseismic data in Italy – updated to 2017 and from which CPTI15 is compiled It contains a list of 245 studies referred to 102 earthquakes with related parameters and also the primary sources we also evaluated the state of knowledge through the critical analysis of data and sources This process mainly focused on the evaluation of the reliability of the primary sources – direct or indirect – and on the existence of explicit references to the earthquake effects at Ischia we tracked any specific doubt or issue that emerged we distilled the content of the inventory by removing fake and doubtful events potentially generated by other phenomena and those generated by seismic sources located outside the volcanic system of Ischia The analysis allowed eliminating 24 events it is worth mentioning some events which derived from the misinterpretation of historical sources (e.g. 1852) and the events of the 1880 seismic sequence located near the Pontine islands (80 km NW of Ischia) The same occurred for more recent earthquakes now relocated by instrumental data in the Tyrrhenian Sea and the 1983 event relocated in the Campi Flegrei area we indicated a record in the catalogue reporting “questionable” in the column “Notes” we also found groups of events not distinguished in terms of time and intensity (e.g. we indicated a record in the catalogue reporting the information about multiple events in the column “Notes” the inventory of the historical earthquakes referring to Ischia consists of 102 events The rich bibliography available for the historical earthquakes of Ischia includes studies based on different geographic positioning of the localities therein analysed; this makes original intensity data (both values and distribution) not directly comparable to each other we applied a homogenization procedure to univocally define a locality and to produce comparable seismic histories as well as earthquake parameters (see next section) In total, we obtained new (revised or produced ex-novo) MDPs distributions for 54 earthquakes, which significantly improved the ASMI database. The MDPs for the largest known earthquakes in Ischia (1828, 1881, 1883, and 2017) are reported in Figure 2 Intensity maps of the largest earthquake of Ischia solid and dashed lines represent the location uncertainty distribution (best guess; 1 and 2 σ areas When multiple studies are available for the 1828 (A,B) and 1883 (C,D) events the location uncertainty distribution represents also the ensemble of the available models (in black When only one study is available [1881 in panel (E); 2017 in panel (F)] the ensemble and the study results coincide To better interpret spatio-temporal variations and characterize the seismic hazard and risk it is critical to homogenize the parameters from different data sources characterizing as much as possible the existing uncertainty we shortly describe how this was achieved for Ischia The epicentral location from intensity data is routinely calculated in the CPTI15 catalogue through the latest version of the “Boxer” code (4.0; Gasperini et al., 2010) we applied the simplest technique for the determination of the epicentre – the so-called “Method 0” – that is calculated as the centre of gravity (truncated average of their coordinates) of the sites with highest intensities since it proved to be robust in case of poor intensity datasets and provided reliable results at Etna where the macroseismic features are similarly characterized by high-intensity attenuation and the extreme concentration of damage in small zones The results of the location estimation are reported in Figures 3A,B; note that the areas represent only the uncertainty of the epicentres and do not indicate any source geometry (A) Location map of the earthquakes included in the macroseismic and instrumental catalogues The size of the symbols is proportional to the magnitude while H and L indicate high and low-quality solutions (B) Location uncertainty for the macroseismic catalogue (only class ‘H’ event) (C) Location uncertainty for the instrumental catalogue an estimation of location uncertainty is of primary importance we first defined a reliability index for the location of the earthquakes based on the number of data available: VL (Very Low) for 1 MDP; L (Low) for 2–5 MDPs; H (High) for MDPs >5 we did not provide an estimation of the epicentre while for those labelled as L we calculated only the epicentre since data are considered not suitable for quantifying the related uncertainty epicentre and related uncertainty are reported for all the events classified as H we exploited the bootstrap method implemented in Boxer 4.0: the code fits a 2D Gaussian distribution quantifying its 2 × 2 covariance matrix so the ensemble model does not differ much from either individual study with the zone of highest probability (1 sigma) substantially covering the maximum damage area we also considered procedures to quantify Mw passing through the estimation of ML We obtained a standard deviation of residuals equal to 0.51 and 0.49 A Md-Mw relationship has been produced by Petrosino et al. (2008; hereinafter PET08; Figure 4A), calibrated on the instrumental magnitude range 0–4 through a standard least-square procedure. Adopting the fit of Petrosino et al. (2008) the uncertainty on Mw evaluation from Md results 0.30 (1 standard deviation PET08 produced a ML − Mw relationship Here we considered the available IMRs to define 3 alternative procedures for estimating Md (models D1 to D3) and 5 for Mw (models W1 to W5), as reported in Table 1 Note that AZZ11 combined with SAR16 (model W5) and PET08 (model W1) was previously adopted in CPTI15 for estimating Mw at Etna and Neapolitan volcanoes To account for the uncertainty of each of these procedures the ensemble takes in input not only best-guess estimates but also sets sampling the existing uncertainty all the models are accompanied by the quantification of uncertainty on the final magnitude for which we assume a normal distribution with a standard deviation equal to the uncertainty declared in the original study To propagate the uncertainty also in the models that consider the sequential application of two relationships (namely the ones to obtain Mw: models W1 to W5) we applied a sequential sampling procedure We first sampled the first uncertainty distribution and then we applied the second relationship to obtain Mw we obtained samples of Mw that propagate the uncertainty of both models Alternative methods adopted to estimate Md and Mw These 3 + 5 models represent all the possible procedures but they cannot be considered equally credible MAR88lin and MAR88log models derive from similar data and mainly differ for large magnitudes which are outside the magnitude range of the original calibration Given that MAR88lin calculates unrealistically high magnitudes which for the largest intensities would require too large fault sources for the size of the island and its seismogenic sources we prefer not to include in the ensemble the models performed with this relationship (Model D2 and W3 for Mw) the remaining models (D1 and D3) were weighted equally for all intensities For Mw we adopted a more elaborate strategy Model W2 provides a slope markedly different from the other models leading to relatively large magnitudes for low intensities and vice versa and therefore we decided to remove it from the ensemble and W5) were differently weighted for low (I0 < VIII) and high (I0 ≥ VIII) epicentral intensities Considering that Campi Flegrei may be considered a volcano-tectonic environment more similar to Ischia but high intensity and magnitude values are available only for Etna we defined the following weights: for I0 < VIII a weight of 2 is given to models including PET08 relationship (Models W1 and W4) and a weight of 1 to the remaining model (Model W5); for I0 ≥ VIII equal weight is assigned to all the models (W1 Numerical values for the obtained IMRs for Mw and Md we report the magnitude estimations for all the earthquakes in the macroseismic catalogue as estimated in Sections “Historical Completeness” and “The Sensitivity of the Instrumental Network and Completeness”: (A) time-span 1000–2019; (B) time-span 1993–2019 The red lines indicate the best guess value for the completeness magnitude (defined in Section “Magnitude-Frequency Distribution” based on the results of Sections “Historical Completeness” and “The Sensitivity of the Instrumental Network and Completeness” for the historical and the instrumental catalogues respectively); the dotted red lines report the assumed uncertainty bounds (+/– 0.2 Mw) for the completeness magnitude used to check the stability of parameters of the magnitude-frequency distribution (more details in Section “Magnitude-Frequency Distribution”) (C) Ensemble magnitude estimation for the 1828 earthquake compared with ensemble’s members (more details in Section “Magnitude”) even if the ensemble model for Mw appears compatible with data the one for Md appears significantly biased toward higher magnitudes also considering an uncertainty of 0.3 on the instrumental Md that both the ensembles would be compatible considering a lower epicentral intensity (I0 = IV) slightly more dispersed than the original distributions the uncertainty of I0 derived from the alternative MDPs is significantly smaller than the one resulting from the IMR we shortly recall the main facts referred to Ischia to evaluate the degree of completeness of its seismic history During the Greek and Roman periods (VIII BC – V century AD), Ischia was populated mainly along the coast (Delizia, 1987). The available sources for this period have recorded only earthquakes associated with eruptions, which dramatically impacted the inhabitants. In the early Middle Ages (VI-X century AD), Ischia was scarcely inhabited (Buchner Niola, 1965; Cundari, 1998) and no information is available about local seismic activity the island began to be part of a wider economic and administrative context for the extraction of alum but the relevant administrative documents were lost during the Second World War bombardments in Naples some contemporary sources recorded two natural events of significant impact for the island The 1302 eruption caused a serious impact on mining determining a depopulation of Ischia until the second half of the XVI century there is a substantial lack of information about facts and events of the island and probably the apparent lack of seismic events cannot exclude the occurrence of moderate earthquakes (I0 < VIII MCS) having left no traces in the few written sources of that time the role of thermal baths became increasingly important for Ischia: the settlements grew and the thermal treatments became the main activity thanks to the proximity to the Neapolitan area the island represented an elite destination for Italian and European tourism so for this period it is very likely that also traces of events of lower intensity should have been reported This condition of cultural interest for the “geological” events occurring in Ischia was strengthened by the foundation of the Osservatorio Vesuviano in Naples in 1841 and of the Osservatorio Geodinamico in Casamicciola in 1885 In conclusion, the results of the analysis of the historical completeness reported in Table 3 show that the catalogue can be considered complete starting from the mid-XVIII century as regards events of moderate intensity (I0 ≥ VII MCS), while the completeness for low intensity earthquakes (I0 ≥ IV MCS) significantly jumps to 1885, when the first local seismic monitoring system was installed at Ischia (Luongo et al., 2012) Completeness of the macroseismic and instrumental catalogues of Ischia based on historical considerations and network sensitivity tests The first seismic sensor deployed on the island of Ischia dates back to 1885, when G. Grablovitz installed a seismic tank in the newly founded Casamicciola observatory (Grablovitz, 1901; Grablovitz, 1902-1903; Ferrari, 2009; Luongo et al., 2012) The first modern seismic station was installed in the same location by the Osservatorio Vesuviano (hereinafter INGV-OV) (station OC9) in 1993 the seismic network has been regularly improved up to the present state Seismic stations at Ischia and Procida operated by the INGV Osservatorio Vesuviano The most recent instrumental seismic catalogue of Ischia, presented by D’Auria et al. (2018), contains earthquakes located or detected from January 1999 until February 2018. Instrumental earthquake data are routinely produced by INGV-OV and periodically updated, and made available on the web (the Ischia instrumental online catalogue)3 in order to save information on the occurrence area of a seismic event the catalogue is integrated with the indications of the felt area As detailed in the next subsections, to enlarge the instrumental dataset and make it comparable with the macroseismic catalogue, we revised the published instrumental catalogue (D’Auria et al., 2018) by (i) extending its time to the pre-1999 period (ii) better characterizing location uncertainties iii) enriching magnitude estimation by adding a derived Mw to the usually estimated Md and reporting also the estimation uncertainty we evaluated the completeness of the revised catalogue The revised catalogue, updated for the time-span from 1991 to 2019, is reported as Supplementary Dataset 3 The revision of the instrumental seismic catalogue was carried out to reconstruct a robust catalogue of pre-1999 seismicity since the first modern seismic station was installed in 1993 The first step was the recovery of the information present in the “Reports on the Surveillance Activity,” periodically prepared by INGV-OV and addressed to the Italian Civil Protection Department From a first comparison between the Reports and information reported in the paper archives we found discrepancies requiring a deeper analysis the archived seismic traces have been visually verified This painstaking analysis allowed us to distinguish between local earthquakes and other transient signals such as anthropic events (explosions by abusive fishermen) in the same area where some events were recently located in 2018 after the improvement of the seismic network Many events cannot be located, because of their low magnitude and the scarce number of seismic stations deployed on the island. The first located event was a Md 1.3 earthquake that occurred in 2007. The situation slightly improved in 2015, when the network passed from three to four seismic stations, and further improved in 2018, when the present-day monitoring network became available (Figure 1 and Table 4) The fairly low seismicity rate recorded in recent times in Ischia prevented also the development of detailed tomographic images by using local earthquake recordings. Three velocity models are currently used to locate earthquakes on the island (Figures 7A–C): Figure 7. Available velocity models and instrumental locations. (A) 1D Velocity models for Campi Flegrei (black, model A in the text) and Ischia (red, model B). (B) 3D velocity model for P waves (model C) for the Neapolitan volcanic district (modified from D’Auria et al., 2008) (C) Hypocentral location adopting the 1D (model A) The 1D velocity model of the Campi Flegrei; B. The 1D velocity model of Ischia, described in Capuano et al. (2015); C. The 3D velocity model described in D’Auria et al. (2008) The 1D crustal models (model A in green and B in blue) are very similar (model A resulting slightly faster than B) while model C shows the greatest differences. Models B and C were obtained by using data from the SERAPIS tomographic experiment (Judenherc and Zollo, 2004) aimed at defining the velocity model of Campi Flegrei despite the presence of some seismic stations on the islands of Ischia and Procida the number of seismic rays crossing the crust below Ischia is relatively low model C has a resolution of 250 m in the Campi Flegrei area which increases up to 1 km for Ischia (whose size is approximately 9 km × 6 km) Model C is characterized by a strong velocity contrast between Campi Flegrei and Ischia results in a highly heterogeneous vertical layer When the estimation of the location was impossible Notably, this estimation does not account for the uncertainty on the velocity model, which can potentially lead to an important underestimation of the effective uncertainty (Husen and Hardebeck, 2010; Garcia-Aristizabal et al., 2020) An indication of the impact of the uncertainty of the velocity model on the location is provided in Figures 7C,D where the largest earthquakes (Md ≥ 0.9) of the 2014–2018 period are located with the A and B velocity models The magnitude reported in the catalogue is the duration magnitude Md, based on coda duration, that allows rapid estimates even when the seismic traces are saturated or the signal to noise level is low (Petrosino et al., 2008) Md is still used to compile the seismic catalogue of Ischia because the magnitude of the recorded earthquakes is usually very low (<2.5) and the seismic stations very noisy In these cases the ML often cannot be estimated we consider an uncertainty of 0.3 associated with low Md values For the events with the highest magnitude (Md ≳ 4.0) the uncertainty quantified in the macroseismic catalogue is probably more appropriate (Section “Step 3: Parameterization of Historical Earthquakes”) In order to allow the comparison between the instrumental and macroseismic local and national datasets, we added the estimate of Md and Mw to both catalogues. For the instrumental one, following the same approach made for the macroseismic part (Section “Magnitude”), we used the Md − Mw relationship defined by PET08 shown in Figure 4A The uncertainty was estimated by combining the uncertainty of Md (assuming a normal distribution with σ = 0.3) with the one of the Md − Mw relationship (normal distribution with σ = 0.3 see Subsection “Magnitude” in Section “Step 3: Parameterization of Historical Earthquakes”) similarly to the procedure adopted for the macroseismic catalogue we sampled both the uncertainty distribution of Md and the one from the Md − Mw relationship for each sampled Md The Mw uncertainty reported in the instrumental catalogue corresponds to 1 σ to the current permanent seismic network (9 stations) and to the integrated seismic network given by the union of the mobile and permanent seismic networks (14 stations) The simulation of the detection and location threshold was carried out down to a hypocentral depth of 1,500 m because the high thermal gradient determines the ductile-fragile transition at a depth of about 2 km (e.g., Carlino et al., 2006; Castaldo et al., 2017; Cubellis et al., 2020) (A) Detection threshold of the seismic network composed of 4 (left) for earthquakes with a hypocentral depth of 500 and 1,500 m The stations’ position is indicated with black stars in the top panels [a and c in panel (A)].(B) Minimum magnitude for locating (4 recordings at least) events with a hypocentral depth between 500 and 1,500 m of depth considering a network with 4 stations (left) whose deployment terminated at the end of October 2017 is able to detect shallow earthquakes of magnitude Md > 0.5 in the whole island (panels b the best coverage remains in the northern area (where the historical main seismicity is concentrated) Note that this network also includes a station on the island of Procida The integrated network (permanent plus mobile stations) has a very high coverage in the epicentral area of the 2017 Casamicciola earthquake in order to identify any aftershocks Figure 8g–l shows the minimum magnitude to locate an earthquake with a hypocentral depth of 500 m (panels g according to the different network configurations The localization level of the current permanent seismic network is around Md = 1 reaching Md = 0–0.5 for very shallow earthquakes (depth 500 m) in the central-northern sector of the island Before the upgrade of the network (concluded in 2018) the location threshold was higher than Md 1.5 on the whole island Merging the earthquakes of the macroseismic catalogue (up to 1992) with the ones of the instrumental catalogue (from 1993) leads to a unified catalogue of 252 earthquakes, covering the time-span from the 8th century BC to the end of 2019. Among them, 78 events are the ones above the completeness magnitudes. The merged catalogue is reported as Supplementary Dataset 4 This represents the most complete and extended catalogue available for Ischia to date we can attempt to characterize the Ischia seismicity from a statistical point of view analysing spatial and magnitude-frequency distributions of the earthquakes and exploring the stationarity process of seismicity The completeness of the unified catalogue is defined according to the results of the historical completeness analysis for the macroseismic catalogue (Section “Historical Completeness”) and the completeness based on network sensitivity (Section “The Sensitivity of the Instrumental Network and Completeness”), adopting for both the moment magnitude Mw (Table 3). In Figures 5A,B the variation of completeness through time is compared with the magnitude estimations reported in the catalogue Given the small number of events and the difficulty in robustly defining completeness the impact of the uncertainty on the parameter estimations (b-value and annual rates) is investigated The tapered GR distribution is described by the equation (Kagan, 2002): where F(M) is the cumulative distribution function for the seismic moment M(F = 1-S, survivor function reported by Kagan, 2002); Mt is the minimum moment; β is the parameter controlling the slope of the distribution, and Mcm is the corner moment that rules the tapering of the right tail of the distribution. Since we adopt Mw in our catalogue, we convert the seismic moment in the previous equation using the Kanamori (1977) formula Comparing with more commonly used parameters and definitions Mt corresponds to the completeness magnitude Mcm to a “corner magnitude” over which the magnitude-frequency distribution decays quicker than a GR and β corresponds to 2/3 of the classical b-value in the following we refer to the classical parameters in terms of magnitude and b-value The smallest explored magnitude (the minimum among completeness levels) is magnitude Mw = 1.0 this method allows accounting for time-variable magnitude completeness and it considers in input the annual rates observed in each magnitude bin (including no observations) evaluated according to the estimated completeness for this magnitude (longer time intervals are available for the larger magnitudes) this method is less sensible than other ones (like the classical MLE) to the small magnitudes recorded only in the most recent part of the catalogue Magnitude-frequency distribution of the Ischia seismicity MLE of the tapered GR model; red dashed lines (B) Uncertainty (blue histogram) and MLE (red line) for b-value estimation (E) Scatter plot (blue points) and MLE (red dot) of the joint estimation of b-value (X-axis) and annual rate (Y-axis) (F) 2D histogram of the joint estimation of the b-value (X-axis) and annual rate (Y-axis); the colour scale represents the density and the red dot the joint MLE (G) Marginal distribution of the annual rate; the red line is the MLE (H) Marginal distribution of the b-value; the red line is the MLE we note that the uncertainties resulting from the parameter estimation with an MLE approach are comparable with the uncertainties considering a Gaussian error (with standard deviation of 0.2) on the evaluation of the magnitude of completeness This means that the obtained results for the magnitude-frequency distribution are robust being not critically dependent on the selected completeness magnitudes The strong correlation between the parameters leads to a non-centred joint MLE with respect to the 2D-histogram whereas the same MLE is compatible with both marginal distributions very similar to the one previously estimated the parameters describing both the complete and the incomplete part of the catalogue in case of a catalogue with a low number of events (<100) if we consider the b-value estimation and the associated uncertainty is still compatible with their findings (i.e. Considering that the largest earthquakes occurred in pre-instrumental times while most of small magnitude events are complete in instrumental times only the future seismicity detectable by the updated seismic network operating since 2018 will give the possibility to further test our findings (e.g. b-value >1) with a more homogeneous dataset while quite large uncertainties exist in magnitude estimations in this analysis we did not explore this uncertainty because most likely it has a quite complex structure that could influence the results the errors on magnitude are probably correlated in the macroseismic part of the catalogue but independent in the instrumental part the observed annual rate of the largest events (from Mw 3.6 complete from 1750) in the period 1750–1884 is 7 times higher with respect to the one in the period 1885–2019 (7 and 1 events Note that the 7 events that occurred during the time-span 1750–1884 are not all independent of each other: indeed, applying a classical declustering method to the catalogue (Gardner and Knopoff, 1974) we computed the probability to observe 6 (or more) events in 135 years the number of observed events in the first declustered sub-catalogue using the annual rate and the b-value estimated in the second sub-catalogue (λ = 6.85/year of Mw ≥ 1.0 We obtained a large majority of low probabilities (<0.05) demonstrating that the Poisson hypothesis for the seismic events’ distribution can be rejected independently from the existing uncertainty on the GR parameters or the magnitudes the seismicity of Ischia described by our integrated catalogue is a non-stationary process and significant modulations in the seismogenic process should be invoked to justify the observed long-term oscillations of the seismicity rate While the non-stationarity process could not be a surprising feature in volcanic seismicity, it is not so obvious in a volcanic system that did not experience any eruption in the last 700 years (last eruption occurred in 1302 AD) as well as volcanic unrest episodes in recent times (Selva et al., 2019) this significant non-stationarity will challenge the assessment of seismic hazard as the available data are sufficient to demonstrate that the Poisson hypothesis commonly adopted in the long-term analyses To analyse the spatial distribution of the earthquakes, we built a very high-resolution model of smoothed seismicity by using cells of 0.005° × 0.005°. Instead of Frankel’s classic smoothed seismicity method (Frankel, 1995), we implemented the innovative method proposed by Hiemer et al. (2014) where the Gaussian smoothing kernel is multiplied by a function that gives more emphasis to the strong past events that occurred when the magnitude completeness of the catalogue was higher to compensate the lack of low magnitude events in the catalogue we can base the smoothed seismicity model catalogue using all the events in the catalogue with a completeness that varies through time instead of using the most recent seismicity only due to the rather limited number of events in the catalogue The method uses the following Gaussian kernel: where Kij is the contribution to the j-th spatial cell of the i-th earthquake in the catalogue; rij is the distance between the i-th event of the catalogue and the centre of the j-th spatial cell; and σ is the so-called correlation distance which regulates the smoothing To obtain the total spatial rate of the j-th spatial cell the contributions of all the N earthquakes in the catalogue must be summed: Kj=∑i=1NKi⁢j Figures 10B–D show the spatial distributions obtained, adopting different σ (0.5, 1, and 1.5 km). We preferred to avoid any optimization procedure, since the total number of data in the catalogue is not large enough to produce a robust inversion of this parameter. The catalogue is declustered adopting the Gardner and Knopoff (1974) method to avoid a fictitious concentration of the spatial rate where past sequences occurred represent the spatial probability density function of the events the sum of the values in all the cells is 1 especially in its western and the central sector In this area is also located the 1863 event the only large event showing rather constant intensity values throughout the island and This means that this larger area cannot be completely neglected as a potential source of future seismicity Noteworthy, adopting the classical Frankel’s (1995) method and/or not declustering even if the classical approach – equal weight to all the events in the catalogue – creates a more homogeneous spatial distribution on the island and less emphasis to the stronger past events mainly clustered in the north-western sector of Ischia This allowed characterizing the statistical properties of the Ischia seismicity its significant non-stationarity also in a period of no eruptions or unrest episodes Log file of the unified earthquake catalogue This study not only provides significant insights into the knowledge of the seismicity of Ischia and its related hazard but also introduces significant novelties into the quantification and use of the uncertainties in the earthquake catalogues and their statistical characterization This is particularly important whenever a limited number of earthquakes is available The characterization and the management of uncertainty are based on the extensive use of the ensemble modelling as well as on the developments of tests that quantify the robustness of the statistical characterization accounting for existing uncertainties the main achievements of this study can be summarized as follows: the macroseismic data well describe the seismic history of Ischia and its seismic style small swarms with few low-energy events concentrated in few months and sequences with a destructive mainshock accompanied by some minor fore- and aftershocks The events which can be parameterized (location 16 of which above the damage threshold (I0 > V-VI MCS) They are being included in the Historical Archive of Historical Earthquake Data (ASMI) and will be used to update the national earthquake catalogue CPTI15 (currently including only 12 events) The standardization of intensity data represents a methodological aspect of interest for future applications • The integration of results from different studies through ensemble models is also an innovative approach to quantify the epistemic uncertainty of parametric data, providing more realistic uncertainty bounds than any single individual procedure (Taroni et al., 2014; Garcia-Aristizabal et al., 2020) The application to Ischia to the 1828 and 1883 events highlights good compatibility of the results from alternative studies Beyond the specific intensity estimates for a given site we are now aware that the relative difference in the earthquake parameters due to subjective factors (selection of localities interpretation of historical sources) or objective ones (the most important of which is the building vulnerability) are relatively minor This is particularly important for the earthquakes having a strong impact on the seismic hazard at the local scale • The extension of the instrumental catalogue as far back as 1991 confirms the very low rate seismicity in recent times The uncertainty on the earthquake parameters when the improvement of the seismic network allowed a better definition of the parameters although a decisive step would derive only from more constrained velocity models potentially including the entire area Ischia-Procida-Campi Flegrei to take advantage also of the Campi Flegrei seismic network • The seismicity is not limited only to the well known seismogenic area of Casamicciola, but is extended to the central part of the island, especially along the faults surrounding the most uplifted part of the resurgent block of Mt. Epomeo (e.g., Selva et al., 2019; Trasatti et al., 2019) While a decrease of the uncertainty in the location estimates may better constrain modulations in its spatial distribution the extension beyond the Casamicciola area is confirmed beyond uncertainty from both the spatial distribution of the instrumental seismicity and the results of standard statistical analyses applied to the entire revised catalogue this result is fairly stable and cannot be considered an artefact of the uncertainty on historical or instrumental locations • The observed Ischian seismicity significantly deviates from a stationary process also taking into account the uncertainty in data The exceptional higher rates of earthquakes with M_w ≥ 3.6 in the years 1750–1884 cannot be explained with the parameters estimated in the years 1885–2019; then a stationary Poisson process is not suitable to describe the Ischian seismicity independently from the application of declustering algorithms observations suggest that significant modulations in the seismogenic process have occurred leading to significant variations of the seismic rate through time The macroseismic data produced in this manuscript will be integrated in the same databases (ASMI, CPTI, and DBMI) in their next releases. 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This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) 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: Jacopo Selva, amFjb3BvLnNlbHZhQGluZ3YuaXQ= 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 In a statement released by the Holy See on The Vatican announced that Cardinal Konrad Krajewski Prefect of the Dicastery for the Service of Charity is visiting the town of Casamicciola Terme situated on the Italian island of Ischia on Thursday the population was dramatically devastated by a flood which caused twelve victims and displaced hundreds of people from their houses The island of Ischia observed a Day of Mourning on Wednesday to coincide with the funerals of those who lost their lives the Cardinal said "Pain cannot be taken away but it can be borne together" And he reflected on the fact that his visit to Ischia takes place on the Solemnity of the Immaculate Conception "To undertake this visit on the Solemnity of the Immaculate Conception has a special significance,” he said who accompanied him until his last breath" the cardinal kissed the hands of the bereaved women was that of the relatives of Valentina Castagna and Gianluca Monti Francesco and Maria Teresa who was just six years old when the landslide swept away their lives “desires that those affected by this grief feel His closeness.” Cardinal Krajewski will donate a Rosary bead to every family “so that they may feel the comfort of His prayer and entrust themselves with hope to the Virgin Mother.” The day after the tragic event, following the Angelus Pope Francis had already asked to remember and pray for “the victims Cardinal Krajewski had already visited Ischia in December 2015 following a violent earthquake that caused the death of two people and at least 2,500 displaced the Cardinal had the possibility to hear the tragic stories of the population and bring and express Pope Francis’ closeness Thank you for reading our article. 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All rights reserved Please enable JS and disable any ad blocker 28 November 2022: Italian rescue services confirmed that 8 bodies have now been recovered from landslides in Ischia Houses in northern parts of the island were damaged or destroyed as a torrent of mud flood water and debris crashed down slopes of Mount Epomeo Some areas were under mud and debris several metres deep Dozens of vehicles were swept into the sea in areas of Casamicciola Terme said at least 150 families are unable to return to their homes The regional government has requested the declaration of a state of emergency A team of over 250 people made up of firefighters civil protection and volunteers are searching for several people still feared missing digging equipment and sniffer dogs have also been deployed Divers were searching the wreckage of the numerous vehicles swept into the sea As of 27 November authorities reported the bodies of 2 victims have been found Poor weather conditions have hampered rescue and damage assessment efforts On 25 November Regional Civil Protection issued warnings for severe weather including heavy rain which could trigger floods and landslides. According to figures from MeteoNetwork the weather station at Forio recorded 133.2mm of rain on 26 November Local media reported 155mm of rain fell in parts of the island in just 6 hours Ischia saw severe flash floods in November 2009 (analysis here) — Matteo Salvini (@matteosalvinimi) November 26, 2022 — Vigili del Fuoco (@vigilidelfuoco) November 26, 2022 — Vigili del Fuoco (@vigilidelfuoco) November 26, 2022 Richard Davies is the founder of floodlist.com and reports on flooding news Cookies | Privacy | Contacts © Copyright 2025 FloodList 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. Volume 10 - 2022 | https://doi.org/10.3389/feart.2022.999222 This article is part of the Research TopicWomen in Science: Seismology 2022View all 6 articles we investigated ground motion directional amplification and horizontal polarization using ambient noise measurements performed in the northern sector of Ischia Island which suffered damage (VIII EMS) during the 21 August 2017 Over 70 temporary seismic stations were installed by the INGV EMERSITO task force whose aim is to monitor site effects after damaging earthquakes in Italy To investigate ground motion directional amplification effects we have applied three different techniques testing their performance: the HVSR calculation by rotating the two horizontal components and time–frequency domain polarization analysis These techniques resulted in coherent outcomes highlighting the occurrence of directional amplification and polarization effects in two main sectors of the investigated area Our results suggest an interesting pattern for ground motion polarization that is mainly controlled by recent fault activity and hydrothermal fluid circulation characterizing the northern sector of the Ischia Island • Directional amplification and ground motion amplification are investigated at the Ischia Island after the 21 August 2017 • Robust results were obtained by applying three analysis techniques in time and frequency domains • The directional amplification pattern and polarization are mainly controlled by recent fault activity and hydrothermal fluid circulation the horizontal ground motion amplitude exceeds 100% of the complementary azimuth angle directional amplification corresponds to linearly polarized ground motion On fractured rock slopes, maximum amplification and ground motion polarization transversal to large open fractures associated with the movement of the slope instability are observed in several papers (Burjánek et al., 2010 and many others). Recently, Burjanek and Kleinbrod (2019) successfully reproduced the observed transfer function on fractured rock slopes by using three-dimensional numerical simulations of seismic wave propagation They confirmed that compliant fractures can generate polarized ground motion and maximum amplification transverse to their strike the effect being primarily controlled by the stiffness This effect results in the time domain in polarization parallel to the fault strike and in the frequency domain to directional amplification in a frequency band depending on the velocity contrast between the fault zone and host rock providing a technique to monitor fluid-driven processes at stressed volcanoes Ischia is composed of volcanic rocks, epiclastic deposits, and subordinate terrigenous sediments, reflecting a complex history of alternating constructive and destructive phases. Lava and tuffs are the more ancient rock of the island that comprise the substratum for all the younger overlaying volcano-sedimentary successions (Figure 1) 60°–85° N dipping synthetic faults overall along the master fault on the resurgent Mt Epomeo N flank (slip-rate exceeding 3 cm/yr between 33 kyr B.P and the present); and 2) a secondary antithetic The combined use of these three different techniques is very important to obtain an overall and complete description of the observed effects and to overcome the limitations intrinsic to each one the HVSR technique can be “non-informative” in some cases (e.g. in the presence of lateral and vertical heterogeneities or velocity inversion) due to the occurrence of amplification on the vertical component of motion signals need to be bandpass filtered; thus it cannot furnish a complete description of the effects in all frequency ranges the time–frequency polarization analysis led to description of the effect versus frequency but it is hard to interpret the results using the quantitative criterion as we will demonstrate in the next sections for the other two methods 1) We use rotated HVSRs to get a grasp on the directional amplification effect quantitatively defining its pattern through several parameters (Section 3.1) 2) We apply the time-domain covariance matrix technique bandpass filtering signals in the frequency bands 0.2–0.8 and 1–5 Hz obtaining an estimate at each station of polarization strength and mean azimuth (Section 3.2) the time–frequency technique was used to validate the results using the two previous techniques in terms of the polarization azimuth (Section 3.3) We ensured the availability of at least 30 time windows at each station The calculation of HVSRs was then performed by rotating the two horizontal components by steps of 10° from 0° to 180°. For each rotated component, we considered a window length of 120 s, 5% tapered, filtered with a fourth-order Butterworth filter in the frequency range 0.1–25 Hz, and smoothed with the Konno–Ohmachi algorithm (b=20, Konno and Ohmachi, 1998) we show directional amplification estimated through the HVSR at two exemplificative stations we also furnish results at the other stations The HVSR curves are plotted separately for each rotation angle (panels a1 and c1) They are also graphed using a contour plot (panels b1 and d1) the x-scale represents the frequency; the y-scale the rotation angle; and the color scale is related to amplitude levels HVSRs show to what extent horizontal motion is amplified compared to vertical motion as a function of the frequency and direction of motion allowing the detection of the frequency band where ground motion tends to be mostly horizontal the directional amplification pattern at each station is defined through the frequency band F0; maximum amplitude (A0); polarization azimuth; and directionality index (DI) Such parameters obtained for the two exemplificative stations are summarized in panels b2 and d2 At first, we found the largest amplitude value (A0) on HVSR curves and read the associated frequency value, that is the frequency peak (F0). In accordance with the SESAME guidelines (2004), we considered an Amax of HVSRs higher than 2 as the basic condition for ground motion amplification. Then, following Pischiutta et al. (2018) and considering the minimum (MinHV) and maximum (MaxHV) amplitude values given at F0 by all rotation angles we automatically estimate at each station: The directionality index was proposed by Pischiutta et al. (2018) to distinguish whether a peak is directional or uniform in the CRISP INGV database (http://crisp.ingv.it) involving all stations of the Italian seismic network They considered a threshold of 1.5 for DI [that is called “function B (f)” in their work] based on authors’ practice and common experience we chose to downgrade this threshold to 1.4 3) The frequency band where the largest amplification falls Further details about the criterion used to objectively interpret the results of HVSR analysis involving DI (f) and C(f) can be found in Pischiutta et al. (2018) Station ESI35 shows two peaks at 0.6 and 1.9 Hz this station is considered to be affected by directional amplification Polarization azimuth values are 90° and 110° for F0 of 0.6 and 1.9 Hz These directions correspond to the maximum amplitude values at the two peak frequencies station ESI17 is not affected by amplification effects and HVSR amplitudes are lower than two in the whole considered frequency band 0.2–15 Hz the remnant parameters are not defined (ND) In order to assess HVSR result variability over small distances, we also processed data acquired by four 2D seismic arrays, whose data and results are described in detail in a complementary paper by Nardone et al. (2022). Stations in each array acquired a simultaneous signal for at least 90 min during daytime, with a sampling rate of 250 Hz. Their locations and results in terms of rotated HVSRs are furnished in the Supplementary Data Sheet S1 the polarization ellipsoid is characterized by three parameters: with λ1 > λ2 > λ3 being the eigenvalues of the covariance matrix R takes values between 0 (pure spherical motion) and 1 (pure rectilinear motion) defined as the angle between the projection on the horizontal plane of the polarization vector and north - Incidence angle I between the polarization vector and the vertical axis: 90° angles indicate horizontal propagation whereas 0° angles correspond to the vertical incidence In order to select polarization azimuth values associated with a horizontal and linear ground motion, we apply a hierarchical criterion proposed by Pischiutta et al. (2012) - Exclusion from statistics values of AZ for which R < 0.5 and I < 45° (that means sub-spherical and nearly vertical polarization ellipsoids) - Linearly normalizing between 0 and 1 the R and I values ranging in the intervals 0.5 ≤ R < 1 and 45° ≤ I < 90° - Calculation of a weight value WH in each time window given by We use as a threshold WH≥0.7 to select AZ values associated with the same time windows. This condition was set consistently with previous papers (Pischiutta et al., 2012, 2018) to ensure that results are representative of a significant part of the signal (i.e. the percentage of rejected time windows had to be lower than 25%) in order to quantify the spread of the azimuthal distribution of the polarization vector and the resultant vector length is defined as follows: The results at two exemplificative stations (ESI35 and ESI17) are shown in Figure 3. Histograms of polarization azimuth values are obtained in the frequency bands 0.2–0.8 Hz (panels a1 and c1) and 1–5 Hz (panels b1 and d1). Similarly, in panels a2, b2, c2, and d2, we also add histograms of the rectilinearity values, given by Eq. 4 polarization azimuth values are concentrated around a mean (N88°±19° and N104°±25° for the bands 0.2–0.8 and 1–5 Hz the RL parameter in both the bands is higher than 0.6 polarization azimuth values are spread (RL ≤ 0.4); therefore a mean polarization azimuth cannot be defined rectilinearity values are lower than those at station ESI35 confirming that ESI17 is not affected by ground motion horizontal polarization effects In the Supplementary Material we add results at the other recording stations Signals are thus decomposed in the time–frequency domain polarization is characterized by an ellipsoid from which the polarization azimuth is defined as the azimuth of the major axis projected to the horizontal plane from North In Figure 4, we show results obtained at stations ESI35 and ESI17. In panels a1 and b1, we plot the ellipticity versus frequency which is defined, according to Vidale (1986) as the ratio between the length of the minor and major axes: ellipticity approaches 0 when ground motion is linearly polarized we found that this parameter is not sensitive enough to distinguish linearly polarized motion we obtained similar values at ESI35 and ESI17 while both the HVSR and covariance matrix techniques highlighted the occurrence of directional amplification at ESI35 and the absence of effects at ESI17 it is hard to find a semi-quantitative criterion to interpret the polarization strength using ellipticity; thus we use this technique only to validate results obtained through the HVSR and covariance matrix techniques in terms of polarization azimuth Azimuth values obtained from all over the time series are cumulated and plotted in panels a2 and b2 and represented using polar plots The contour scale represents the relative frequency of occurrence of each value; the distance to the center represents the signal frequency in Hz (panels a2 and b2); and white dotted circles indicate frequencies of 1 Hz The mean polarization azimuth and standard deviation are calculated at stations where the HVSR analysis highlighted the occurrence of directional amplification we obtained values of 83°±14° and 114°±22° considering HVSR peak frequencies of 0.6 and 1.9 such parameters were not defined since the HVSR technique did not reveal any directional amplification effects Results for time–frequency polarization analysis at stations ESI35 (A) and ESI17 (B) It is defined as the ratio between the length of the minor and major axes and approaches 0 when ground motion is linearly polarized polarization azimuth values obtained from all over the time series analyzed are cumulated and graphed using polar plots where the contour scale represents the relative frequency of occurrence of each value and the distance to the center represents the signal frequency in Hz Dashed circles depict frequencies of 1 Hz In previous sections, we described the three methodologies and the analysis flow (Section 3) that we applied to investigate ground motion directional amplification and polarization. Their combined use furnished redundant results and led to a robust estimate of the observed effect overcoming limitations intrinsic to each of them. In the Supplementary Table S2 we report analysis results for the three techniques for the two frequency bands They include the estimation of the following parameters: - Covariance matrix analysis in the time domain after bandpass filtering signals in two frequency ranges, 0.2–0.8 Hz and 1–5 Hz: Polarization azimuth AZ (with associated standard deviation) and resultant length RL (Section 3.2). The condition for polarized ground motion is given by RL >0.4, and when not satisfied, the parameter AZ was not estimated (indicated as “ND” in Supplementary Table S2) - Time–frequency analysis: Polarization azimuth AZ and standard deviation (Section 3.3) were evaluated in the frequency equal to F0 when DI>1.4 (otherwise indicated as “ND” in Supplementary Table S2) we give the final effect in terms of the geographical direction evaluated as a mean of azimuth values and in terms of the frequency band (from the HVSR analysis) In Figure 2 and in Supplementary Figures S1–S11, we show results at all stations. Moreover, in Supplementary Figure S12 we add some examples for inconsistent results suggesting that such discrepancies are related to the strict constraints that we use to distinguish between directional/non-directional and polarized/non-polarized motion we also produce maps of the resultant length RL by using an inverse distance squared interpolation red colors correspond to linearly polarized motion while blue colors correspond to non-polarized motion Results obtained in the two frequency bands 0.2–0.8 Hz (top panel) and 1–5 Hz (bottom panel) The inset in the left-bottom is focused on Casamicciola village Faults in the area are reported (red lines) as is the causative fault of the 2017 earthquake (blue line) Stations with directional amplification and polarization effects are depicted through red triangles Polarization azimuth distribution is plotted as a rose diagram Contour maps of the resultant length are produced using an inverse distance squared interpolation (red colors correspond to linearly polarized motion) The high-angle effects of the fault strike are also evident in the NE sector of the investigated area and close to the coast with polarization tending to be oriented in the NNE–SSE direction (stations ESI36 nearly orthogonal to ESE–WSW faults) polarization at a high angle to the fault strike is observed only in the frequency band 0.2–0.8 Hz while they are absent in the frequency band 1–5 Hz suggesting that such effects are produced by heterogeneities at deeper depth (hundreds of meters considering shear wave values in the order of 300–600 m/s) However, when approaching the active normal fault (red lines in Figures 1, 3), polarization tends to be fault-parallel, even following fault strike oscillation from ENE–WSW to EW. This is also in agreement with the coseismic ruptures (yellow lines in Figures 1, 3) and causative fault of the 2017 earthquake (blue lines in Figures 1, 3) This effect is evident in both frequency bands (0.1–0.8 Hz and 1–5 Hz) and due to the high number of installed stations it is particularly clear in the sector of Casamicciola village that suffered the highest damage (X MCS) during the last earthquake (see the inset in the bottom panel) we propose the following two hypothetical explanations for this parallel relation between ground motion polarization and the strike of these active system faults becomes parallel to fracture) and seismic anisotropy fast direction (which further analyses are needed to test this latter hypothesis implying a study of seismic anisotropy to confirm the occurrence of a 90° flip our stations did not record any seismic events earthquake recordings at stations of the temporary network installed by INGV to detect aftershocks are poor and not appropriate for anisotropy studies A final consideration regards the possibility that observed amplification may be due to the Mt. Epomeo topography, such as due to constructive interference of seismic waves diffracted by the convex shape of topography, according to the “topo resonant model” (Burjanek et al., 2014a; Burjanek et al., 2014b) where the resonance frequency is related to the hill dimension and the mean shear-wave velocity (Géli et al. Epomeo topography since the effect is clearly concentrated close to the causative fault of the 2017 earthquake particularly in the frequency band 0.2–0.8 Hz amplification due to topography convexity is expected on the top stations showing amplification are mainly located at the lower slope of Mt and stations installed at the middle slope do not show any effects (e.g. - We determined polarization and directional amplification patterns in northern Ischia across active fault systems responsible for the 2017 Md 4.0 earthquake considering both the main and secondary amplification peaks - Our observations suggest that horizontal polarization patterns depend on the site and are mainly controlled by the local geology, as suggested by several other studies on fault zones (Marzorati et al., 2011), volcanoes (Falsaperla et al., 2010; Cusano et al., 2020a; Cusano et al., 2020b), and landslides (Burjanek et al., 2010) - On older faults and geomorphological lineaments, we found polarization at a high angle to the fault strike, consistent with several studies (Panzera et al., 2014) MP and SP contributed in the field by collecting seismic noise data. MP analyzed data to assess directional amplification and time–frequency polarization. SP analyzed data to assess ground motion polarization through the covariance matrix analysis. RN provided comparison with geological and structural data that she collected in other previous published works. MP wrote the manuscript draft and produced Figure 2 and the Supplementary Material All authors contributed to the manuscript writing and in result interpretation The authors are grateful to the INGV EMERSITO task force which carried out data acquisition in the field after the 2017 Casamicciola earthquake Part of this work has been developed in the framework of the INGV research project POLARTIME: POLARization analyses To Image crustal structure and fluid Migration Episodes at Ischia island (Ricerca Libera 2021) 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.2022.999222/full#supplementary-material The interaction between regional and 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This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use *Correspondence: M. Pischiutta, bWFydGEucGlzY2hpdXR0YUBpbmd2Lml0 from family-friendly Sorriso Thermae to the dolce vita time capsule Albergo della Regina Isabella Many may have first heard of Ischia through Elena Ferrante's Neapolitan novels but Italians have long adored this verdant volcanic island in the Gulf of Naples for its spectacular sea views and the healing powers of its thermal springs Ischia's mineral-charged thermal waters – terme – were discovered 3,000 years ago by the Ancient Greeks The bubbling fonts quickly became famous for their restorative properties rheumatism and all manners of skin conditions thanks in no small part to Ischia's year-round mild climate and lush hiking trails Today, there are dozens of thermal spring experiences throughout Ischia – ranging from ultra-glam resorts to rugged natural bays. To uncover some of the best, we spoke to Italian spa industry insider Raffaella Dallarda a holistic expert and spa guidebook writer who has visited every thermal spa in the country "In Italy we have more than 400 certified natural springs but the kingdom of the natural springs in Italy is Ischia." That's because Ischia's waters receive an extra charge from the volcanic craters in the seas surrounding the island "[It's] called L'Isola Verde; the Green Island," said Dallarda [And] the volcanic waters are hotter than waters in other places [in Italy] They have more positive properties on joints Ischia is the perfect escape for anyone who desires a laidback "A spa has a character," said Dallarda Here are Raffaella Dallarda's picks for the most relaxing and spectacular spas on Ischia Best of the best: San Montano Resort & Spa Of all the thermal spa experiences on Ischia, Dallarda cites the San Montano Resort & Spa as her all-time top pick "There's this incredible 360-degree view of the bay It feels like you're floating in the sea just surrounded by all these gorgeous thermal and sea water pools… and in the hotel everywhere there are those locally made ceramic floor tiles." The stately mountaintop five-star resort boasts various levels of luxury villas and suites plus the splendid Lemontano citrus grove "Inside the grove they have these sunbeds set up like it's an outdoor spa," explained Dallarda "And they give you massages right there in the grove with all the lemons dangling above your head It's absolutely insane." The San Montano Resort also has a traditional spa as well as indulgent face and body treatments all with jaw-dropping panoramic views of the sea and Mt Vesuvius It's like being on a cruise ship," said Dallarda "San Montano is the absolute best." Website: https://www.sanmontano.com/ Instagram: @sanmontanoresort Best for living out your dolce vita dreams: Albergo Della Regina Isabella the families that participated in film festivals used Ischia as their summer house "All the celebs from Los Angeles like Bridgit Bardot… they were all guests in the gorgeous Rizzoli villa It's retained that vintage 1960s style Located in a quiet bay in the hamlet of Lacco Ameno Albergo Della Regina Isabella stuns with its original brightly patterned tile floors ornate furnishings and mesmerising sea views "They have this private pier where everyone comes in with their yachts," said Dallarda The hotel's thermal springs are classified as "hyper-mineral waters" flowing at a temperature between 56C and 77C Dallarda notes that the hotel's spa is a bit of an anomaly – a high-grade clinical structure plopped amid vintage glamour "Even the uniforms of the therapists… it's very clinical." utilising Ischia's natural volcanic mud which absorbs new microelements helpful for treating inflammation and improving blood circulation and get ready for an Aperol Spritz at sunset Website: https://www.reginaisabella.com/it/ Instagram: @regina.isabella Best for a romantic getaway: Mezzatorre Hotel & Thermal Spa Dallarda's pick for couples is the Mezzatorre Hotel & Thermal Spa in the village of Forio I was there for a wedding once – they lit up the tower with fireworks to make it look like an attack on the castle The five-star hotel and thermal spa is housed in a red 16th-Century Aragonese watchtower perched high up on a cliff overlooking the Mediterranean Sea Mezzatorre was also an 18th-Century ducal palace the hub of a cultural circle that included renowned poets and film directors "They do these open-air massages under the gazebos as you watch the yachts pass by It's a 'wow' place," said Dallarda And take note that it's on a promontory – gorgeous view… it's very romantic for couples." Website: https://www.mezzatorre.com/en/ Instagram: @mezzatorrehotel Best sustainable experience: Botania Relais & Spa Botania Relais & Spa offers a 100% organic sustainably produced menu prepared with homegrown ingredients "If I had to give an award for the breakfast The sprawling grounds are situated in a botanic garden; a series of whitewashed deluxe cottages with modern ceramic tile flooring and tasteful colourful interior décor Guests are free to explore the beautifully manicured English-inspired gardens before visiting the Garden Spa where they'll find hot and cold plunge pools and a steam shower housed in a beautiful natural grotto They can then retire to the treatment rooms to indulge in expert massages and bespoke skin and body treatments but high-standing and so unique," said Dallarda Website: https://www.botaniarelais.com/ Instagram: @botaniarelais Best for vintage Neapolitan glamour: Excelsior Belvedere Hotel & Spa "It's frequented by high-class Neapolitans… the noble families," she said of the 19th-Century aristocratic sea-view villa Just a short distance from the lively Corso Vittoria Colonna shopping street and awe-inspiring Aragonese Castle the Excelsior Belvedere enjoys sweeping views of the Gulf of Naples and its seemingly endless sky The lobby and rooms are a time capsule of 1960s Italian island luxury – rich brocade drapery and colourful tiled floors – while the spa is a stunning seashell-shaped haven with marble statues and wall-to-wall mosaics Guests can choose to bathe in the mineral-packed thermal waters get slathered in therapeutic muds or choose from a long menu of beautifying Website: https://www.excelsiorischia.it/en/ Instagram: @excelsiorischia Best medical spa: Hotel Continental Ischia "[It] has a very interesting medical spa," said Dallarda "And is a favourite among Italian families who demand very Italian-centred services." Hotel Continental Ischia's staff uses the reserve of thermal waters and mud found 39m beneath the property to treat ailments ranging from musculoskeletal diseases and post-accident traumas to respiratory concerns and vascular disorders To benefit from an Italian medical spa's treatments visitors must undergo a medical pre-examination and commit to a treatment course Website: https://www.hotelcontinentalischia.it/en/ Instagram: @continentalischia Best for quality water treatments: Giardini Poseidon Terme it's easy to see why Giardini Poseidon Terme is so popular: its structure not only manages to blend country-club vibes with white-washed Italian island architecture it's also adjacent to a breathtaking strip of beach with craggy cliffs and sea views But Dallarda likes Giardini Poseidon Terme for a far more practical reason: the quality of its waters "[The health director] is very fanatic about research," she said "They are the best place [on Ischia] for balneotherapy… They have 20 pools and every night they clean the waters immaculately ultra-natural water therapy without any skin irritation the only place is [Giardini Poseidon Terme]." Giardini Poseidon Terme's spa offers a full menu of wellness high-tech face and body aesthetic treatments as well as mud and thermal water-charged medical services "The service is great," said Dallarda "If you're looking strictly for glamour Website: https://www.giardiniposeidonterme.com/en Instagram: @giardiniposeidon.terme Best for families: Sorriso Thermae Resort & Spa "It's a little hard to get to – you have to cross the island to get there," said Dallarda "But it's really family-oriented… [you see] grandparents with their grandchildren people who don't want to spend too much." Sorriso Thermae Resort & Spa – sorriso means smile in Italian – has been making families happy since the 1960s with its vintage Mediterranean-style tile-and-mosaic ornamented decor grand ocean-front restaurant and beach-adjacent swimming pool "There's a really large spa," said Dallarda "[It's] popular for its medical treatments Even for its rejuvenating treatments; they've got the mud And they're open all year round… For its quality-to-price ratio it's a good family destination." Website: https://www.sorrisoresort.it/en Instagram: @sorriso.resort.ischia Best for those on a budget: Hotel Terme Tritone Resort & Spa "[It's] a four-star [hotel] in Forio with a great spa with great service," said Dallarda "[It's] basically private residences with a British cottage feel and the English-inspired gardens are extremely well tended." "Not everyone can afford the Mezzatorre The Tritone is a good compromise where the spa is lovely and does a great job," said Dallarda Website: https://www.hoteltritoneischia.it/en/ Instagram: @hoteltritoneischia BBC Travel's The SpeciaList is a series of guides to popular and emerging destinations around the world as seen through the eyes of local experts and tastemakers Join more than three million BBC Travel fans by liking us on Facebook, or follow us on Twitter and Instagram If you liked this story, sign up for the weekly bbc.com features newsletter called ”The Essential List”. A handpicked selection of stories from BBC Future, Culture, Worklife and Travel, delivered to your inbox every Friday. Rome's most stunning optical illusions revealedFrom the Malta Knights keyhole to a set of vanishing columns, discover the Eternal City's visual secrets. 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From the economy to the climate and the EU's role in world affairs, this talk show sheds light on European affairs and the issues that impact on our daily lives as Europeans. Tune in to understand the ins and outs of European politics. No agenda, no argument, no bias, No Comment. Get the story without commentary. Dare to imagine the future with business and tech visionaries Deep dive conversations with business leaders Euronews Tech Talks goes beyond discussions to explore the impact of new technologies on our lives. With explanations, engaging Q&As, and lively conversations, the podcast provides valuable insights into the intersection of technology and society. Europe's water is under increasing pressure. Pollution, droughts, floods are taking their toll on our drinking water, lakes, rivers and coastlines. Join us on a journey around Europe to see why protecting ecosystems matters, how our wastewater can be better managed, and to discover some of the best water solutions. Video reports, an animated explainer series and live debate - find out why Water Matters, from Euronews. We give you the latest climate facts from the world’s leading source, analyse the trends and explain how our planet is changing. We meet the experts on the front line of climate change who explore new strategies to mitigate and adapt. Grief, dismay and still many questions are up in the air following a landslide that left at least eight dead and four missing on the Italian island of Ischia. A wave of mud and debris caused by heavy rain devastated the small town of Casamicciola Terme in the north of the island, situated off the coast from Naples, early Saturday morning. The Italian press also reported that 13 people were injured. Rescue work is still ongoing this Monday with teams having to remove tons of mud to access the interior of several houses. Search operations have been complicated by persistent rain and strong winds, which have also delayed the arrival of reinforcements by ferry from the mainland. Among the dead are two children and a newborn baby. By Sunday evening, Italy's government declared a state of emergency on Ischia. A first emergency package of €2 million was also agreed at an extraordinary government meeting on Sunday, said the Minister of Civil Protection Nello Musumeci. But for many, the move is too little and too late. Anger has been growing among the population over the years of illegal construction that partly contributed to the disaster. It is estimated that thousands of houses and other buildings were constructed under illegal permits on the island. The head of the national civil protection agency told the Italian newspaper La Stampa that 94% of municipalities in the country are "at risk of flooding, landslides, or coastal erosion". Saturday's landslide sent torrents of mud down the streets, knocking down trees and carrying away and denting vehicles, sometimes into the sea.  It also "buried a house" and two people were rescued from a car that had been driven into the sea, the fire service said. Casamicciola Terme, a winter resort of 8,000 people on the lush island of Ischia near Capri, suffered an earthquake in 2017 that killed two people. It had, however, been entirely destroyed by a much more powerful earthquake in the late 19th century. Saturday's disaster came just weeks after 11 people died in floods caused by heavy rains in east-central Italy. Reporting by Alvise Armellini and Elvira Pollina the head of the Ischia engineers association debris and stones broke away from the island's highest mountain showed investment was needed for safety."We need to plan canals and routes for these flows of mud," he told Reuters.($1 = 0.9537 euros)(This story has been refiled to fix typo in paragraph 3)Reporting by Angelo Amante; Additional reporting by Elvira Pollina; Editing by Keith Weir and Alison Williams your new go-to podcast to spice up your weekday mornings with relevant news and behind-the-scenes from Brussels and beyond From the economy to the climate and the EU's role in world affairs this talk show sheds light on European affairs and the issues that impact on our daily lives as Europeans Tune in to understand the ins and outs of European politics Euronews Tech Talks goes beyond discussions to explore the impact of new technologies on our lives the podcast provides valuable insights into the intersection of technology and society Europe's water is under increasing pressure floods are taking their toll on our drinking water Join us on a journey around Europe to see why protecting ecosystems matters and to discover some of the best water solutions an animated explainer series and live debate - find out why Water Matters We give you the latest climate facts from the world’s leading source analyse the trends and explain how our planet is changing We meet the experts on the front line of climate change who explore new strategies to mitigate and adapt Experts and activists have said that the construction of illegal buildings increased the risks of natural disasters on the Italian island of Ischia One person was still missing after Saturday’s disaster in the port of Casamicciola Terme where houses were brought down and mud submerged the streets Authorities confirmed on Thursday that the death toll had risen to 11 after the bodies of two missing women were found The confirmed victims included the 22-day-old infant and two other young children heavy rain caused a chunk of Mount Epomeo to come crashing down before dawn gaining speed as it entered the populated port town of Casamicciola The World Wildlife Fund said the ground in the worst hit areas composed of agglomerated ash and rock from nearby Mount Vesuvius on the mainland it is the site of rampant unauthorised construction "This material doesn't perfectly attach itself to the island’s surface its triggers a sort of snowball effect which goes downstream and accumulates in high-risk areas the President of Italy's WWF research centre "Everyone knows that Italy is a fragile country But not everyone knows that risk areas have been surveyed and mapped with accuracy "Today over 16% of the Italian territory is in high-risk areas" he continued whose thermal baths and picturesque hilly coastline draw visitors from across the world is known for its high concentration of residential buildings Geologist Arcangelo Francesco Violo said that Ischia which sits in an earthquake zone across the sea from Naples According to environmentalists and the mayor of Forio local authorities in the hardest hit area received over 27,000 requests under successive government amnesties since 1985 to gain official approval for structures that in some way violated building codes “it's not that 27,000 villas have been built illegally or 27,000 flats have been built illegally people will think that the island is completely covered in concrete.” the Legambiente chief in the Campania region around Ischia said excessive construction had weakened the land and urged authorities to remove buildings that did not have permits  Granting amnesties for illegal construction put people at risk The Casamicciola town bureau in charge of buildings could not immediately be reached for comment As a political row about the granting of the amnesties gathered pace Environment and Energy Minister Gilberto Pichetto Fratin said in a statement he would seize illegal buildings to investigate them for safety with pardons granted only for small violations Prime Minister Giorgia Meloni's government earmarked an initial aid package of €2 million for Ischia and suspended tax payments for residents until the end of the year said the tragedy on the island’s highest mountain Seven confirmed dead and search continues for people missing after Saturday’s disaster on Ischia As rescuers continued to search for five people still missing after a catastrophic landslide in Ischia anger was growing on the southern Italian island on Sunday over the years of rampant illegal construction that contributed to the disaster Seven people, including a three-week-old baby and a pair of young siblings, are confirmed to have died in Saturday’s landslide which was triggered by a violent storm that sent mud and debris from Monte Epomeo crashing into the hamlet of Casamicciola Terme One victim – 32-year-old Eleonora Sirabella – has been named a five-year-old girl and her 11-year-old brother a 31-year-old island resident and a Bulgarian tourist “Mud and water tend to fill every space,’’ Luca Cari Men carry possessions through a street covered in mud after landslides on Ischia Photograph: Roberto Salomone/The GuardianThe same hamlet was hit by a landslide in 2009 and damaged again by an earthquake in 2017 trees uprooted and cars swept into the sea in the latest tragedy Ischia landslide mapGiorgia Meloni’s government the first tranche of a fund that will be spent on repairing the damage as he cleared mud from the entrance of what was a hotel owned by his family “This is the second time I’ve had to do this – after the 2009 landslide they made lots of promises to make the area more secure The storm, which followed days of heavy rain across much of Italy is reported to be the worst in 20 years to have hit Ischia Rescuers search for survivors on the beach following the landslide on Ischia Photograph: Roberto Salomone/The GuardianCasamicciola Terme is home to just over 2,000 people and lies in an area of the island – known for its natural hot springs and popular with Italian and foreign tourists – that is extremely vulnerable to landslides and seismic activity Seventy-two landslides were registered to have occurred in the hamlet between 2018 and 2021 The number of illegally built homes and other buildings – estimated at 28,000 across the island – has been blamed for exacerbating the damage Vincenzo Capuano Photograph: Roberto Salomone/The Guardian“They’ve been giving permits to people to effectively build illegally since the 1920s,” said Vincenzo Capuano as he assessed the destroyed premises of what was his cultural association “So we’re not talking about just a few years is friends with a man in his 60s who was hospitalised on Saturday after being pulled alive from the thick mud The illegal building also meant that trees which play an essential role as buttresses in reducing landslide risk Experts also say that a geological survey assessing the risks in the area was last done 20 years ago “This is a region predisposed to landslides,” said Micla Pennetta a professor of geomorphology at Federico II University in Naples “So much of the devastation in the past has influenced the current morphology of Ischia but on top of the natural aspects we have deforestation and subsequent cementification – this reduced the capacity for water to be absorbed enabling it to rapidly reach roads and homes Pennetta added: “Not only has the geological map done 20 years ago not been updated but it was never detailed enough to properly identify the risks then people can build wherever they want.” Ischia has a population of about 22,000 and although it attracts far less attention than its more glitzy neighbour over the years the island has drawn a crowd who prefer more low-key holidays including the former German chancellor Angela Merkel and who want to experience its natural hot springs The island enjoyed a robust tourist trade this summer the busiest season since the start of the coronavirus pandemic a taxi driver whose colleague is waiting for news of a relative who is among those missing “This is a terrible tragedy for the island.” a vast complex built in 1854 that sits upon hot springs dating back to the Roman era “The springs have been totally saturated,” said Carmine Bernardo a crowd of people gathered at the port of Casamicciola where rescuers were searching the sea for possible victims Vehicles retrieved from the sea lined the shoreline and more storms are forecast in Ischia and other parts of Italy in the coming days A resident rides his Vespa through a muddy street Photograph: Roberto Salomone/The Guardian“This is a tragedy that should never have happened,” said Pascquale Manco who partly blames the scant maintenance of Mount Epomeo “They [the authorities] also set aside money after the 2009 landslide for maintenance The mountain has not been taken care of the way it should have been when what we need are prevention measures.” whose husband’s cousin is among those missing “We can only carry on hoping they find people alive,” he said “Hope is the last thing to fade even if the reality tells us something different.” At least 12 people are missing and one person confirmed dead after a devastating landslide swept through the Italian island of Ischia early Saturday morning leaving a pile of debris and mud throughout the hillside neighborhood on the popular vacation island off the coast of Naples Vehicles were dragged to the sea in Ischia following heavy rains that sparked a landslide furniture and trees scattered along the Italian hillside leaving debris strewn throughout the neighborhood injured more than three dozen and left significant damage in the Ischia towns of Casamicciola and Lacco Ameno Italy landslide: Deaths feared after homes swept away in Ischia (BBC) A woman was found dead and around 10 people were still missing on the southern Italian holiday island of Ischia after a landslide engulfed buildings during heavy rain on Saturday The landslide struck in the town of Casamicciola Terme following heavy rainfall in the early hours of the morning bringing serious flooding to the northern part of the volcanic island in the Tyrrhenian Sea about 30 kilometres from Naples "Currently the confirmed death toll is one and there still are around 10 missing," the prefect of Naples Claudio Palomba told a news conference Italy's interior minister said that a dozen people were missing There was confusion after Deputy Prime Minister Matteo Salvini said that eight people had died with authorities saying no deaths had been confirmed at that stage The Italian fire brigade tweeted that a rainstorm that started at 0500 CET caused flooding and landslides on the island while a car was dragged into the sea and the two occupants were rescued with mud and water reaching the first floor of the houses The fire brigade mentioned difficulties in reaching the island with motorboats and helicopters due to bad weather The landslide is said to have produced heavy damage in the Casamicciola and Lacco Ameno area said that families in danger were being evacuated Prime Minister Giorgia Meloni said she was in close contact with the Civil Protection minister Nello Musumeci the Civil Protection Department and the Campania Region "to follow the evolution of the wave of bad weather that has hit Ischia" "The government expresses its closeness to the citizens and mayors of the municipalities on the island of Ischia and thanks the rescuers engaged in the search for the missing" Island near Naples was engulfed by heavy rain causing a landslide that flooded homes and swept away cars A woman has died and 10 people are missing after a severe storm triggered a landslide on the Italian island of Ischia with the landslide hitting the hamlet of Casamicciola Terme early on Saturday morning flooding homes and sweeping away several cars had earlier said that eight people had died But by Saturday evening there was one confirmed death with 10 people still missing The first victim was confirmed to be a woman whose body was found by rescuers according to a media briefing by the prefect of Naples He said some of those reported missing earlier were later found safe but about 10 other people were still unaccounted for by mid-afternoon The rescue effort was hampered by continued rain and high winds which also delayed ferries bringing reinforcements from the mainland had earlier warned there were people trapped in the mud A 60-year-old man was taken to hospital with serious injuries Electricity has been cut off in the affected area and about 30 families have been stranded in their homes in the hamlet of Lacco Ameno where several buildings are reported to have collapsed houses have been uprooted by the landslide,” police chief Tiziano Laganà told La Repubblica a parish priest at Santa Maria Maddalena church in Casamicciola Terme told the Ansa news agency: “I’m calling people who may be missing but unfortunately I have not yet received an answer I’m trying to get there but the road beneath my house is blocked by a wall of cars and trees.” Ischia has a population of about 20,000 and is popular with Italian and foreign tourists Ferries to and from the island have been suspended the number of missing people in Casamicciola is still uncertain,” said Ferrandino earlier on Saturday “Due to bad weather on the island of Ischia we also have situations in other areas but fortunately not particularly serious.” In 2017, Casamicciola was struck by an earthquake in which 42 people were injured A landslide in the hamlet in 2009 killed a 14-year-old girl Much of Italy has been hit by heavy rain over the past week 13 people were killed by severe flooding in the central Marche region The text and headline of this article were amended on 26 November 2022 An earlier version stated that at least eight people were dead in the light of updated information received This is the archive of The Observer up until 21/04/2025 The Observer is now owned and operated by Tortoise Media Landslides have destroyed buildings and left residents cut off on the Italian holiday island of Ischia Heavy rainstorms and flooding caused several landslides in the town of Casamicciola Terme which is around 20 miles off the coast of Naples Please use Chrome browser for a more accessible video player Follow us on Instagram for the most striking images from the very center of life in the air and the land Tuesday World Subscribers only Friedrich Merz bets on two private sector converts to revive the German economy and reform the state World Subscribers only 'A Pope in the tradition of Francis': From New York to Ghana Catholics hope for continuity at the Vatican World Subscribers only Chancellor Merz's diplomatic first week 2025."> World Trump's proposal to reopen Alcatraz deemed 'absurd' in San Francisco World Subscribers only Founder of Sant'Egidio community fears next pope could undo Francis's legacy Opinion Subscribers only 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Subscribers only 'The trade war creates new opportunities for Europeans and France' Magazine Subscribers only Tracking down the pianos taken from French Jews during the Nazi Occupation Magazine Subscribers only Eve Rodsky the American helping couples balance the mental load Magazine Subscribers only Desecration or more glory Joan Didion's private diaries are revealed Magazine Subscribers only For Jewish cartoonist Joann Sfar 2025."> Pixels Subscribers only Golden Owl solution is revealed but leaves players of 31-year hunt disappointed Pixels Subscribers only Secrets of decades-long Golden Owl treasure hunt to be revealed Lifestyle Inside Chanel's French leather workshops Culture Subscribers only The marvelous bronzes of Angkor on display at the Musée Guimet in Paris An entire section of the island's mountain slid into the sea on November 26 after heavy rains By Allan Kaval (Rome (Italy) correspondent) A house narrowly escaped the landslide that ravaged the town of Casamicciola on the Italian island of Ischia on November 26 SALVATORE LAPORTA/AP Beneath a gloomy sky from the top of Mount Epomeo to the gray waters of the Gulf of Naples the devastated landscape visible from the last accessible stretch of the Via Celario tells the full story of the Italian island of Ischia: its fragility after a few hours of unusually heavy rainfall an entire section of the mountain slid toward the sea in an avalanche of mud and loose volcanic rock The scar left by its passage begins near the peaks passing through old abandoned chestnut tree plantations It then branches out across the landscape and roads laid out for cars which wind their way along the mountainside toward the sea the hotels and restaurants deserted in this off-season nine bodies had already been found on the route of the mudslides rescue workers were digging through the rubble of a house the stance of the men in uniform evoked a heaviness somehow linked to the presence of death Other corpses were still buried up there between the mud the stones of the mountain and the concrete of the houses The residences were built in a regulatory blur that everyone – although for different reasons – is pointing the finger at for having proved lethal You have 84.14% of this article left to read Lecture du Monde en cours sur un autre appareil Vous pouvez lire Le Monde sur un seul appareil à la fois Ce message s’affichera sur l’autre appareil Parce qu’une autre personne (ou vous) est en train de lire Le Monde avec ce compte sur un autre appareil Vous ne pouvez lire Le Monde que sur un seul appareil à la fois (ordinateur En cliquant sur « Continuer à lire ici » et en vous assurant que vous êtes la seule personne à consulter Le Monde avec ce compte Que se passera-t-il si vous continuez à lire ici Ce dernier restera connecté avec ce compte Vous pouvez vous connecter avec votre compte sur autant d’appareils que vous le souhaitez mais en les utilisant à des moments différents Nous vous conseillons de modifier votre mot de passe Votre abonnement n’autorise pas la lecture de cet article merci de contacter notre service commercial 29 November, 2022 By The devastation caused by Saturday's landslide on the southern Italian island of Ischia was made worse by "unplanned" and "inappropriate" urban development on the island The disaster occurred on the morning of 26 November when a violent storm hit the port of Casamicciola Terme and the streets were filled with mud and debris flows Italy's agency for fire and rescue service Reuters reported that the landslide has killed at least eight people Firefighters are continuing to search for four people who are still missing in Casamicciola Terme Proseguono a Casamicciola Terme (NA) le operazioni dei #vigilidelfuoco per la ricerca dei dispersi. Nella clip il lavoro del team #USAR e delle squadre nella zona di via Celario [#29novembre 10:45] USAR = Urban Search and Rescue pic.twitter.com/XZeUP69HXH — Vigili del Fuoco (@vigilidelfuoco) November 29, 2022 The island around 30km from Naples is a volcanic island with steep slopes that sits on an earthquake zone a magnitude four earthquake on the island killed two people and caused several buildings to collapse University of Hull vice chancellor and landslide specialist Dave Petley reiterated the point made by various media outlets - including the Guardian - that unauthorised construction on the island could have made the impacts of these natural disasters worse In a blog post on 28 November he wrote: “Landslides have occurred on many previous occasions and the risk has been greatly exacerbated by unplanned urban development in locations that are simply inappropriate Much of this development has occurred over the last three decades.” He pointed to drone footage which shows that the path of the landslide ran straight through Casamicciola and ended at the sea where it deposited vehicles and the remains of buildings “In Hong Kong this would be termed a natural terrain landslide The drone footage appears to indicate that it initiated on the very steep upper reaches of the slope as a comparatively small failure in weathered rock The channelised flow has then entrained large volumes of debris to generate a highly destructive flow,” he continued Reuters reported that geologist Arcangelo Francesco Violo said that there has been a “chaotic development of buildings and an improper use of land” on the island He claimed this has made the situation for the island “There are buildings in places where geological conditions would not allow construction," he told Reuters According to Italy’s Civil Protection Department, as many as 94% of Italian municipalities are at risk of landslides and floods. In an interview with La Stampa earlier this week head of the department Fabrizio Curcio said that “all of Italy” is at risk Prime minister Giorgia Meloni's cabinet has declared a state of emergency for the area and approved €2M (£1.73M) in funds for recovery and rescue operations Want to read more? Subscribe to GE’s enewsletters and follow us on Twitter and LinkedIn Tagged with: Network Rail has completed a £33M project to stabilise a “large and complex” active landslide that has been disrupting a railway line in County Durham for 150 years Kent County Council is seeking government support for the “vital reinstatement” of the A226 road in Swanscombe damaged by a chalk cliff collapse two years ago Retaining wall works are expected to enable the reopening of Dalton Bank Road The North and Mid Wales Trunk Road Agent is considering engineering solutions for a landslide damaged section of the A470 near the River Wye Sign in or Register a new account to join the discussion AVBOB celebrates a milestone by rewarding its members on a large scale Italy's government declared a state of emergency on Sunday after a landslide on the southern island of Ischia killed at least one person and left a dozen missing A wave of mud and debris hit the small town of Casamicciola Terme early Saturday morning engulfing at least one house and sweeping cars down to the sea A first tranche of two million euros relief funds was released at the end of an emergency cabinet meeting which declared the state of emergency said Minister for Civil Protection Nello Musumeci.  More than 200 rescuers are still searching for a dozen missing people are busy cleaning the streets of the town.  Wreckage of cars and buses crushed by the mudslide could be seen and boulders were scattered around as excavators sought to free up access to homes Rescuers had recovered the body of a 31-year-old woman if only for the people who disappeared under the mountain Here it's an island and even if we don't really know everyone hotels and that was already happening nine years ago Now I am cleaning my mother-in-law's shop," he said.  The landslide was caused by a lack of maintenance and prevention "because nature is nature but a bit of prevention" could have saved lives is no stranger to states of emergency following earthquakes a spa resort of 8,000 inhabitants in winter on the lush island of Ischia was hit by an earthquake in 2017 that killed two people.  The slow but continuous lowering of Mount Epomeo could be the cause of the major earthquakes that hit the island in the past This interpretation is given by a study conducted by Ingv and Cnr What produced the magnitude 4 earthquake that struck Ischia on 21 August The main cause could be the load exerted by the rocks that form the block of Mount Epomeo on others The subsidence of this block generates seismic activity along a surface of sub-vertical discontinuity extending in an east-west direction for about 2 km and the same depth a study conducted by a team of researchers from the National Institute of Geophysics and Volcanology-Vesuvian Observatory (Ingv-Ov the Institute for Electromagnetic Sensing of the Environment (Irea Naples) and the Institute of methodologies for environmental analysis (Imaa Potenza) of the National Research Council (Cnr) in collaboration with the Department of Civil Protection (Dpc entitled "The 21st August 2017 Ischia (Italy) earthquake source model inferred from seismological have been published in Geophysical Research Letters "The availability of satellite radar data from the Sentinel-1 constellation and those from the COSMO-SkyMed constellation from the Italian Space Agency (ASI) and the Ministry of Defence" "has made it possible to detect a subsidence of the ground up to a maximum of 4 cm is located at a small depth in the northern sector of the island "Its identification was possible thanks to a multidisciplinary approach that made it possible to integrate seismological and GPS (global positioning system) data from the Ingv networks with satellite radar data processed by the Cnr" “The earthquake of 21 August 2017 was the first seismic event with destructive effects on Ischia was formed due to the lifting of rocks deposited on the bottom of a caldera in the central part of the island thanks to the thrust exerted by a magmatic intrusion The Epomeo rocks are the product of the great eruption of the Green Tufo of Mount Epomeo the island has been the site of numerous eruptions; the last one dates back to 1302 Today it is characterized by fumarolic and hydrothermal activity and by sporadic seismicity the last earthquake with catastrophic effects on the island was the earthquake of 1883 which caused over 2300 deaths and the destruction of 80% of the building stock in the town of Casamicciola That event was the first earthquake that the newborn Italian state had to manage also the parents and sister of Benedetto Croce who was miraculously extracted alive from the rubble shows the value of collaboration between research institutions which has always been promoted by the Dpc on civil protection issues contributing to the geological knowledge of Ischia They elaborated an explanatory model of the dynamics of the area providing the first instrumental data of moderate degree seismicity in Ischia and calculating the characteristics of the source of the earthquake of August 21 Attached image: 3D view of the vertical component of ground displacement estimated from Sentinel-1 and COSMO-SkyMed data and of the discontinuity surface that generated the seismic event of August 21 2017; the white dots represent the main seismicity recorded The contents published on these pages by theNational Institute of Geophysics and Volcanology are distributed under license Creative Commons Attribution 4.0 International License.  2017 a series of earthquake tremors affect the island of Ischia The National Institute of Geophysics and Volcanology announces that the event located in the municipality of Casamicciola Terme the Institute specifies that the data relating to the magnitude duration is 4.0 an estimate used to measure events in the volcanic area The damage is limited to a very limited area north of the island to which unfortunately a second one will be added The Head of Department Angelo Borrelli convenes the Civil Protection Operational Committee which meets in the presence of the President of the Council of Ministers Following what emerged during the Committee three teams of the Department are sent to the territory in support of local and regional authorities an increase in the contingents of various Operating Structures is provided for in particular the Fire Brigade with units specialising in search and rescue About 750 men and women of the National Civil Protection Service are working on the island a few hours before the event and about 140 vehicles are employed including machines The arrival of the forces on the island is possible thanks to the synergic contribution of the components of the State which in order to ensure the movements of men and means On August 22nd the President of the Council signed the declaration of the "Risk of compromising primary interests" entrusting the coordination of the first aid interventions to the Head of the Civil Protection Department through the Components and Operational Structures of the National Service of Civil Protection Priority was given to the Rizzoli hospital which was initially evacuated as a precautionary measure Write to Contact Center protezionecivile@pec.governo.it Italian rescuers were searching for a dozen missing people on the southern island of Ischia on Sunday after a landslide killed at least one person as the government scheduled an emergency meeting A wave of mud and debris swept through the small town of Casamicciola Terme early Saturday morning with other local media reporting that 13 people had been injured in the incident About a dozen people were still unaccounted for by early Saturday evening But some people who had earlier been reported missing had since been found safe Prime Minister Giorgia Meloni tweeted her sympathy to those affected saying she had called an extraordinary cabinet meeting on Sunday to discuss the disaster "We are afraid that there might be other victims but so far the current figure is one dead," Luca Cari The rescue effort was hampered by rain and high winds Interior Minister Matteo Piantedosi had earlier warned there were people trapped in the mud he denied a statement by his colleague Matteo Salvini the deputy prime minister and infrastructure minister - Complex rescue operation -Heavy rain sent torrents of mud through the streets of Casamicciola Terme a lush island near Capri that is thronged with tourists in summer Trees were upturned and cars left battered on the side of the road or in the water The fire service said earlier one house had been overwhelmed by the mud and two people had been rescued from a car that had been swept into the sea at least 30 families were trapped in their homes without water or electricity Officials said they expected to evacuate and find temporary homes for between 150 and 200 people by Saturday evening "The rescue effort remains complex due to the weather conditions," said the department for civil protection but it stressed teams would keep working through the night Local authorities called on residents of Ischia to stay inside to avoid hindering the rescue operation Casamicciola Terme was hit by an earthquake in 2017 The devastation in Ischia comes just weeks after 11 people died in heavy rain and flooding in the central Italian region of Marche please register for free or log in to your account.