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During the last years, several crustal seismic sources have been proposed in El Salvador; however, the actual destructive potential of these proposals has not been revealed yet. Here we present several seismic scenarios related with the main crustal faults in the country. We have characterized the corresponding hazard scenarios in a deterministic way, estimating the peak ground accelerations (PGA) including local site effects. In addition, we present a list of 29 sources that can be considered potentially dangerous with their main features when they are available and four seismic scenarios that we consider to be more probable. We have resorted to the February 13th 2001 Mw 6.6 destructive earthquake, the only earthquake occurred in a known crustal source in El Salvador and recorded by the strong motion network, in order to test the methodological approach and the reliability of the PGA results predicted by two available Ground Motion Prediction Equations (GMPEs) including the site effect. The consistence between the values given by the models and the ones recorded during the event provides reliability to our results. This approach allowed us to conclude that faults within the volcanic arc can produce accelerations up to 1 g in the most conservator case (Mw = 7.0), while accelerations up to 0.6 g are usual results related with specific faults within the Salvadoran Volcanic Arc. Besides, the reported damage distribution of the 8th June 1917 earthquakes and its similarity with one of the proposed scenarios allowed us to infer the possible source of this event, the Guaycume Fault. [ABSTRACT FROM AUTHOR]

The 28th September 2018 Sulawesi Supershear earthquake (M W 7.5) was one of the deadliest earthquakes in the recent history of Indonesia causing ∼4000 causalities. The earthquake caused a ∼ 177 km long surface rupture along the Palu-Karo fault. Apart from surface rupture, the earthquake caused extensive earthquake environmental effects (EEEs) around the Palu-Donggala area of Central Sulawesi, Indonesia, which includes tsunami, coastal landslide, liquefaction, ground cracks and more than 7300 landslides in hilly areas. Initial post-event analysis and reports assigned a Modified Mercalli Intensity (MMI) of VII to VIII in Palu City and the surrounding area. Building damage and ground effects caused by the earthquake suggested that seismic intensity was understated. Here we applied the EEEs information from field survey data, published reports, and remote sensing tools to determine macroseismic intensity using the Environmental Seismic Intensity (ESI-07) Scale. The ESI-07 intensity derived from the ground effects suggests the maximum intensity of X-XI, which is 3–4° higher than the traditional intensity estimated by the United States Geological Survey (USGS) and the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). ShakeMaps were generated considering the ESI-07 values. The ShakeMap was compared with the instrumentally derived ShakeMap for the Palu earthquake, which proves that the ShakeMap prepared from the instrumental data or structural damage data is underrated. We argue that proper documentation of the EEEs is necessary for such damaging earthquakes for future earthquake hazard mapping and planning in the study area and other earthquakes in Indonesia. In addition, this will help in defining the on-fault and off-fault damage zone towards reducing the seismic risk of the Palu Donggala area. • Detailed Earthquake Environmental Effects (EEEs) caused by the 28/09/2018 Sulawesi earthquake (M w 7.5) were collected. • The epicentral ESI-07 intensity as well as the site specific intensity were estimated. • The ESI-07 intensity were compared with Skala Intensitas Gempabhumi (SIG), BMKG. • ESI-07 ShakeMap were generated using the Surface Rupture data and ESI-07 values. • The maps can be used to guide efficient and strategic seismic hazard assessment and land use planning. [ABSTRACT FROM AUTHOR]

The source of the 1886 Charleston, South Carolina earthquake influences the computed seismic hazard of the Southeastern U.S. and thus impacts public policy and engineering practice. However, because the 1886 rupture predated seismic instruments, its source is highly uncertain. This study presents probabilistic seismic-source inversions of the Charleston earthquake from liquefaction evidence and historical intensity reports. Using the latest predictive models and a novel inversion approach, we seek to constrain the magnitude, location, and orientation of the 1886 rupture. Probability distributions of rupture magnitude are conditioned on both the "Woodstock Fault" – a commonly inferred source of the 1886 event – and on an unknown source, wherein the uncertainties of fault location and orientation are considered. These distributions are compared to the M w 6.7-M w 7.5 distribution adopted by the U.S. National Seismic Hazard Model Project (NSHMP). Collectively, the results do not provide strong support for the hypothesized Woodstock Fault. This is not to say the Woodstock Fault does not exist or could not have caused the 1886 rupture, but rather, that the position of the 1886 source model cannot be constrained by the data and models studied herein, given the large uncertainties inherent to each. While this is at odds with the underlying assumption of prior studies, the results nonetheless generally uphold the magnitude distribution adopted by the NSHMP. The largest uncertainties inherent to this distribution are identified and could be diminished in the future. Finally, we note that the inversion methodology used here is not specific to any region, or to certain types of evidence, but can be applied to any seismic zone and to any co-seismic response. This methodology allows for uncertainty to be accounted for in a more complete and transparent manner when inverting seismic source parameters from macroseismic data. Of course, any limitations, biases, or unmodeled uncertainties inherent to these data must be understood, and their implications acknowledged, as further discussed herein. • The source of the 1886 Charleston earthquake influences the computed seismic hazard of the region but is highly uncertain. • The earthquake's source is probabilistically inverted from liquefaction evidence and felt intensity reports. • The results do not provide strong support for the Woodstock Fault – an often inferred source – which is not to say it does not exist. • While this is at odds with the assumption of many prior studies, the results generally support the magnitude distribution adopted by the National Seismic Hazard Modeling Project. • Our approach allows for more complete accounting of uncertainties when inverting seismic sources from macroseismic data. [ABSTRACT FROM AUTHOR]

This paper presents a probabilistic approach for seismic stability analysis of a slope at a given site in a specified exposure time. For a probabilistic seismic stability analysis, the ground motion parameter, in terms of the peak ground acceleration (PGA), at a given site in a specified exposure time of interest (say, 30 years) is treated as a random variable, and the PGA distribution at the given site is derived based on the USGS National Seismic Hazard Maps data. Further, the spatial variability of the soil property is simulated herein by a random field, and the fluctuation of the groundwater level is simulated by a random variable. Within the probabilistic framework, a deterministic model for evaluating the slope stability is required; here, a pseudo-static analysis is adopted and implemented through 2D finite difference program FLAC version 7.0. In the face of the uncertainties in the input parameters, the performance or safety of the slope is expressed as a failure probability; within the proposed probabilistic analysis framework, a recently developed sampling method is adopted for the uncertainties propagation through the deterministic solution model. This probabilistic analysis framework is demonstrated with an illustrative example of a two-layer earth slope. Finally, a parametric study is undertaken to investigate how the failure probability of the slope (at a given site in a specified exposure time) is affected by the uncertain factors such as the earthquake-induced ground motion and the spatial variability of soil property. The study results demonstrate the versatility and effectiveness of the proposed framework for probabilistic seismic stability analysis of slope at a given site in a specified exposure time. [ABSTRACT FROM AUTHOR]

Seismic site amplification and seismic hazard maps are crucial inputs for decision making and risk evaluation in places where seismicity imposes a significant risk to human life and infrastructure. In this work, we propose a novel machine learning (ML) based methodology to integrate qualitative and quantitative data to map the degree of seismic amplification in an area of Chile, one of the most seismically active countries on Earth. Our method uses measurements of surface shear wave velocities (V s30) and predominant frequencies (f 0) combined with gravity anomaly maps to update the geographic extension of seismic amplification classes. Additionally, we trained the predictive models to interpolate and extrapolate V s30 and f 0 to the unsampled sites. Applying this method to the Santiago basin resulted in (i) a refined seismic amplification map, and (ii) maps of V s30 and f 0 estimated with improved accuracy. The best predictions, obtained by ML techniques and validated through cross-validation, are possibly due to the inclusion of spatial covariates for algorithm training, enhancing the ability of the model to capture the spatial correlations of geological, geophysical and geotechnical data. The estimation of predominant frequencies (f 0) is improved considerably by including gravity as a covariant. The accuracy of the f 0 predictions apparently depends more on the choice of covariates than on the algorithm used, while the V s30 predictions are more sensitive to the chosen algorithm. These results illustrate the great potential of machine learning predictive algorithms in digital soil mapping, which surpass traditional geostatistical techniques. The major contribution of this work is to introduce a novel methodology, based on artificial intelligence models, to extend local measurements of site-specific dynamic properties. This information can be used to quantitatively estimate seismic hazard over a regional scale. • We propose a methodology for integrating data to map dynamic site characterization using machine learning. • Our method uses measurements of Vs30 and f0 combined with gravity anomaly and geology. • We trained predictive models to interpolate Vs30 and f0 in the Santiago de Chile basin. • The best predictions were obtained thanks the inclusion of spatial covariates for algorithm training. • The estimation of f0 is considerably improved by including gravity as a covariant. [ABSTRACT FROM AUTHOR]

The Sichuan-Tibet Railway in eastern Tibet runs across numerous seismogenic faults with high seismic risks. The Lancangjiang fault (LCJF), one of the essential strike-slip faults within the Qiangtang block, traverses the railway. However, the geometry and late Quaternary activities of the LCJF remain unclear, limiting the assessment of seismic hazards on the Sichuan-Tibet Railway and the understanding of kinematic patterns in eastern Tibet. Based on the interpretation of high-resolution satellite imagery, field observations, and shallow geophysical exploration, we first mapped the detailed geometry of the northern LCJF. It consists of two branches: Yangda-Yaxu fault (YYF) and Baqing-Leiwuqi fault (BLF), which merge eastwards onto the main LCJF. Displaced landforms and multiple numerical dating techniques reveal that the YYF is a mainly sinistral fault with a late Quaternary slip rate of ~2.2 + 0.6/−0.5 mm/yr and a minor vertical component (~0.1 mm/yr). The BLF undergoes an oblique motion with a left-lateral slip rate of ~1.2 + 0.5/−0.3 mm/yr and a northeast-vergent reverse rate of ~1.2 + 0.4/−0.2 mm/yr in the Holocene. Vector analysis of slip rates suggests that the LCJF has a sinistral rate of ~3.5 + 1.1/−0.8 mm/yr with a reverse component of ~1.6 + 0.4/−0.3 mm/yr, displaying an essential role in strain partitioning of eastern Tibet. Together with slip rates of other intra-block faults, the kinematic pattern of eastern Tibet probably applies to the sub-block model. Offset geologic units yield a total displacement of ~10–11 km for the YYF. Using the slip rate of the YYF, the LCJF was initiated at ~5.9–3.9 Ma, probably related to the establishment of the present-day strain pattern and the onset of crustal thickening in eastern Tibet during the late Miocene. In addition, the active YYF and BLF across the Sichuan-Tibet Railway have a seismic potential of Mw ~7.2–7.3 that will produce a ~ 1.8–2.0 m sinistral slip on the YYF, and a ~ 2.0 m horizontal, and ~ 1.1–1.3 m reverse motion on the BLF. They will pose a high seismic hazard potential on the railway. This study provides quantitative data for regional seismic hazard analysis and shows insights into the deformation mechanism of the plateau. • The geometry of the northern LCJF is first mapped. • The northern LCJF has a late Quaternary ~3.5 mm/yr sinistral and ~ 1.6 mm/yr reverse rate. • The seismic potential of the northern LCJF on the Sichuan-Tibet Railway is estimated. • The LCJF takes an important role in strain partitioning in eastern Tibet. • The initiation of the LCJF is related to the late-Miocene tectonic event in eastern Tibet. [ABSTRACT FROM AUTHOR]

The uncertainty assessment for the development of the new seismic hazard maps of Spain is explained in this work. A detailed description of how uncertainties are considered in the different phases followed for the probabilistic seismic hazard assessment study is presented. Special emphasis is given to the characterization of the uncertainty of earthquake size parameters contained in the catalog, and their propagation to subsequent phases of the analysis such as catalog homogenization, completeness and declustering. Aleatory and epistemic uncertainties are examined and assessed using Monte Carlo simulations and a logic tree, respectively. The final impact of uncertainty in hazard estimates is evaluated through coefficient of variation maps, showing the areas where larger and lower variability is obtained. The hazard maps developed in this work are intended to be the basis for the future revision of the Spanish seismic code. [ABSTRACT FROM AUTHOR]

In the 2008 Wenchuan earthquake, the mass ejection type of high-speed and long-run-out landslide was an unusual hazard characterized by its dramatic phenomenon of a huge slope mass launching into the air and becoming airborne for a long distance. Quantitative and qualitative combined techniques were applied to reveal the formation mechanism of this type of landslide. Four prerequisites critical to form mass ejection are identified: high position of the toe of the surface of rupture, critical height and critical inclination of slope, sufficient open space in the movement direction, and adequate take-off speed of ski-jump-like mass ejection. These four area-specific prerequisites provide a promising approach for screening and targeting the potential landslides. Subsequently, a dynamic reliability analysis method that considers the feature of energy–time distribution is proposed. This site-specific method provides a more credible evaluation by emphasizing the most significant period within the whole earthquake duration. Finally, an aerodynamic inverse method combined with an energy-conservation-based method is applied in the quantitative evaluation to calculate take-off speed of mass ejection. This paper provides a viable solution for regional screening and site assessment for new potential targets of this type of landslide. [ABSTRACT FROM AUTHOR]

Abstract: The seismic hazard value of any region depends upon three important components such as probable earthquake location, maximum earthquake magnitude and the attenuation equation. This paper presents a representative way of estimating these three important components considering region specific seismotectonic features. Rupture Based Seismic Hazard Analysis (RBSHA) given by Anbazhagan et al. (2011) is used to determine the probable future earthquake locations. This approach is verified on the earthquake data of Bhuj region. The probable earthquake location for this region is identified considering earthquake data till the year 2000. These identified locations match well with the reported locations after 2000. The further Coimbatore City is selected as the study area to develop a representative seismic hazard map using RBSHA approach and to compare with deterministic seismic hazard analysis. Probable future earthquake zones for Coimbatore are located considering the rupture phenomenon as per energy release theory discussed by Anbazhagan et al. (2011). Rupture character of the region has been established by estimating the subsurface rupture length of each source and normalized with respect to the length of the source. Average rupture length of the source with respect to its total length is found to be similar for most of the sources in the region, which is called as the rupture character of the region. Maximum magnitudes of probable zones are estimated considering seismic sources close by and regional rupture character established. Representative GMPEs for the study area have been selected by carrying out efficacy test through an average log likelihood value (LLH) as ranking estimator and considering the Isoseismal map. New seismic hazard map of Coimbatore has been developed using the above regional representative parameters of probable earthquake locations, maximum earthquake magnitude and best suitable GMPEs. The new hazard map gives acceleration values at bedrock for maximum possible earthquakes. These results are compared with deterministic seismic hazard map and recently published probabilistic seismic hazard values. [Copyright &y& Elsevier]

Abstract: Seismic hazards in greater North China were estimated from 500years of intensity observations. Historical intensity observations were collected, the completeness of the earthquake catalog was tested, and aftershocks were deleted. The intensity data were digitized and placed in a geographic information system (GIS). Finally, the digitized intensity data were analyzed to determine the frequency–intensity relationship (i.e., seismic hazard curve). Seismic risks were also estimated, assuming a Poisson distribution for earthquake occurrence in time. The results show that greater North China faces significant seismic hazards and risks. The results also show that the current design peak ground acceleration (PGA) for greater North China might not be adequate, particularly for the Beijing, Tianjin, and Tangshan areas. [Copyright &y& Elsevier]

Abstract: This paper aims at the analysis of seismic wave amplification in a deep alluvial basin in the city of Tunis in Tunisia. This sedimentary basin is 3000m wide and 350m deep. Since the seismic hazard is significant in this area, the depth of the basin and the strong impedance ratio raise the need for an accurate estimation of seismic motion amplification. Various experimental investigations were performed in previous studies to characterize site effects. The boundary element method is considered herein to assess the parameter sensitivity of the amplification process and analyze the prevailing phenomena. The various frequencies of maximum amplification are correctly estimated by the BEM simulations. The maximum amplification level observed in the field is also well retrieved by the numerical simulations but, due to the sensitivity of the location of maximum amplification in space, the overall maximum amplification has to be considered. The influence of the wave-field incidence and material damping is also discussed. [Copyright &y& Elsevier]

Abstract: Effects from the disastrous Ms 8.0 Wenchuan Earthquake of May 12, 2008 show that the seismic hazard is closely related to the proximity of active faults and elevated areas of unstable rock as well as the recurrence rate of large earthquakes. Dextral-slip thrusting in the Longmenshan Mountains formed large displacement along ~250km of the Central Longmenshan Fault and smaller offsets along sub-parallel faults. The distribution pattern of the major destruction has a strong northeast–southwest orientation closely related to the ruptured faults and decreases noticeably 3–5km away from the Central Longmenshan Fault and ~2km from the other faults. Thousands of landslides, rock falls and debris flows triggered by the earthquake lie chiefly adjacent to the principal fault, and smaller-scale landslides along the other faults as well as in distant areas. Some landslides formed dams whose impounded waters threatened downstream cities. Future landslides, rock falls and debris flows will result from rock loosened by the earthquake during rainy seasons or subsequent earthquakes. The Central Longmenshan Fault had maximum displacements of 4.6m dip-slip and 6.1m dextral-slip and the total dip and dextral-slip displacement for all faults is 5.9m and 7.0m, respectively. These faults apparently converge at depth and account for the crustal shortening in the region. Their displacements coupled with convergence rates determined by GPS measurements provide an estimated recurrence interval for an Ms 8.0 earthquake along the Central Longmenshan Fault of between 4600 and 6600years and that for the entire Longmenshan Mountains between 1000 and 3000years. [Copyright &y& Elsevier]

Abstract: A method for total risk analysis of embankment dams under earthquake conditions is discussed and applied to the selected embankment dams, i.e., Chang, Tapar, Rudramata, and Kaswati located in the Kachchh region of Gujarat, India, to obtain the seismic hazard rating of the dam site and the risk rating of the structures. Based on the results of the total risk analysis of the dams, coupled non-linear dynamic numerical analyses of the dam sections are performed using acceleration–time history record of the Bhuj (India) earthquake as well as five other major earthquakes recorded worldwide. The objective of doing so is to perform the numerical analysis of the dams for the range of amplitude, frequency content and time duration of input motions. The deformations calculated from the numerical analyses are also compared with other approaches available in literature, viz, Makdisi and Seed (1978) approach, Jansen''s approach (1990), Swaisgood''s method (1995), Bureau''s method (1997), Singh et al. approach (2007), and Saygili and Rathje approach (2008) and the results are utilized to foresee the stability of dams in future earthquake scenario. [Copyright &y& Elsevier]

Many devastating earthquakes inflicted heavy casualties and property losses in the seismically active China Seismic Experimental Site area (CSES: 97.5° ~ 105.5°E, 21° ~ 32°N). We performed a first-order seismic zoning based on Neo-deterministic Seismic Hazard Assessment (NDSHA) in the study area delimited by 94° ~ 108°E and 19° ~ 35°N, containing the South-East margin of the Tibetan Plateau and the Sichuan-Yunnan region. The seismic hazard is expressed by maps of peak ground displacement (PGD), peak ground velocity (PGV) and design ground acceleration (DGA) values, extracted from synthetic seismograms computed at a regional scale and mapped on a regular grid of 0.2° × 0.2° over the study area. For the computation of synthetic seismograms, we considered and updated all the available geophysical-geological-tectonic information, including historical and instrumental earthquake catalogues, seismogenic zones, seismogenic nodes, focal mechanisms, and geophysical structural models. We tested the performance of our assessments with available data (i.e., after the Great Wenchuan (2008, May 12th, M s = 8.0) and Lushan (2013, April 20th, M s = 7.0) earthquakes) and verified the negligible influence of large events located "far" from the study area. The results indicate the high seismic hazard of the region, with a particular attention (i.e., where DGA > 0.6 g) to the areas located around the main fault zones, e.g., the Longmenshan, Anninghe and Zemuhe Fault Zones. These first-order NDSHA zoning findings may serve as a knowledge basis to support both large- to mid-range preparedness actions and (multi-scenario) site-specific studies. • Neo-Deterministic Seismic Hazard Assessment maps for China Seismic Experimental Site. • The "predictive" power of NDSHA before and after the 2008 M 8.0 Wenchuan earthquake. • Validation of NDSHA against instrumental records of the 2008 M 8.0 Wenchuan earthquake. • Formulation of seismic hazard maps derived from M design for efficient practical applications. [ABSTRACT FROM AUTHOR]

Abstract: The Netherlands has large on-land gas reservoirs, which are being exploited since 1960. Small-magnitude (M L ≤3.5), shallow (depth<4 km) events induced by this gas exploitation cause light damage and much concern to the regional population. As one of the consequences the Dutch law requires since 2003 seismic hazard and risk estimates for each mining concession. Up to now only general quantitative hazard estimates, maximum possible earthquake and maximum possible intensity were available. Here we provide more specific quantitative hazard estimates. A long-term monitoring program shows a stationary rate of seismicity since 1992, probably coupled to a stationary production rate. Based on this we present a first order site-specific hazard estimate using a Probablistic Seismic Hazard Analysis (PSHA). We predict, and observe, relatively high Peak Ground Accelerations (PGA). PGA above 0.2 g is not unusual, but damage has so far been restricted to non-structural damage, mainly cracks in masonry. Relevant hazard estimates for the local, mostly low-rise buildings are given in terms of Peak Ground Velocity (PGV) or the maximum in the 50% damped response spectra at 10 Hz. For example, above the largest Dutch gas field, the Groningen field, we expect that peak values of 20 and 30 mm/s may be exceeded with a 10% probability in 1 and 10 years, respectively. Above some small (about 3–4 km2) gas fields, Roswinkel and Bergermeer, we expect values around 35 and 60 mm/s, respectively. These values, which exceed the Dutch building research (SBR) vibration guidelines, are obtained using simple model assumptions and are accompanied by an uncertainty analysis. The PSHA provides an important additional insight for the decision maker as to which relevant uncertainties may be decreased and which not. This information can be and is being used to set research and monitoring priorities. [Copyright &y& Elsevier]

Abstract: Earthquakes induced by gas production are a social concern in the Netherlands. Over the last two decades, a total of about 350 such earthquakes have been recorded, with magnitudes ranging up to 3.5 on Richter''s scale. The new Dutch mining law prescribes the operators to give a quantitative estimation of the likelihood of future seismic activity (hazard) and the associated damage (risk). This estimation has to be given for every onshore field (producing, or to be produced). A traditional probabilistic seismic hazard analysis (PSHA) can not give an estimation of the hazard for a field before the occurrence of seismic activity. We have therefore investigated the correlation between parameters related to reservoir and production properties and the occurrence of induced seismicity in a hydrocarbon field statistically, using Bayes'' theorem and the Rule of Succession. Three key parameters have been identified that show a good correlation with the occurrence of earthquakes: pressure drop, fault density of the reservoir and stiffness ratio between seal- and reservoir rock. Based on the observed correlation a probability for the occurrence of earthquakes in fields that have no historical earthquake record has been calculated. This has resulted in the definition of four groups of hydrocarbon fields having all a different probability. [Copyright &y& Elsevier]

Because the instrumental records of Turkey are far from being satisfactory for modeling the seismic hazard using the probabilistic approach, an attempt was made in this study to accomplish it through the deterministic way. In this regard, all active faults of Turkey, small and large, were evaluated together to obtain major fault systems. Then, the procedure suggested by Wells and Coppersmith [Bull. Seismol. Soc. Am. 4 (1994) 975] applied to those faults to obtain the maximum magnitude earthquake that they can generate. To do this, it was assumed that 1/3 of the total fault length would rupture to yield the maximum earthquake. Following that, seven different attenuation relationships of the strong ground motion were utilized to calculate the maximum horizontal ground accelerations for the whole Turkey at 0.2° intervals using the computer model TUMDES written in BASIC programming language.The computed peak ground acceleration (pga) values were contoured and the iso-acceleration map based on Sadigh et al. [Seismol. Res. Lett. 1 (1997) 180] relationship was selected as the new seismic hazard map of Turkey on which the seismic zonations were determined as following: pga>0.3 g Zone 1; 0.3 g

Recent developments in the neotectonic framework of Turkey introduced new tectonic elements necessitating the reconstruction of Turkey''s seismic hazard map. In this regard, 14 seismic source zones were delineated. Maximum earthquake magnitudes for each seismic zones were determined using the fault rupture length approximation. Regression coefficients of the earthquake magnitude–frequency relationships for the seismic zones were compiled mostly from earlier works. Along with these data, a strong ground motion attenuation relationship developed by Joyner and Boore [Joyner, W.B., Boore, D.M., 1988. Measurement, characterization, and prediction of strong ground motion. Earthquake Engineering and Soil Dynamics, 2. Recent Advances Ground Motion Evaluation, pp. 43–102.] was utilized to model the seismic hazard for Turkey using the probabilistic approach. For the modeling, the “earthquake location uncertainty” concept was employed. A grid of 5106 points with 0.2° intervals was constituted for the area encompassed by the 25–46°E longitudes and 35–43°N latitudes. For the return periods of 100 and 475 years, the peak horizontal ground acceleration (pga) in bedrock was computed for each grid point. Isoacceleration maps for the return periods of 100 and 475 years were constructed by contouring the pga values at each node. [Copyright &y& Elsevier]

The emergency management system is a complex network consisting of structural components, such as buildings, infrastructure and emergency areas, and non-structural elements, such as procedures, emergency workers, information management, etc. This document describes the evaluation of only its structural components. The system was adopted at the territorial scale and is defined by a multi-municipality area extension. This paper presents a methodology for the probabilistic evaluation of operating the emergency structural system in the case of a seismic event occurrence and, in detail, it highlights the methodology for calculating the seismic hazard including seismic local effects (amplification and permanent co-seismic effects). Systemic seismic risk and associated impact were considered in a rigorous and unified way. Moreover, the importance of the interconnection and interdependence between elements at risk belonging to the same system and between different networks at urban or territorial scales is well known. The aim of the proposed methodology is to evaluate the operational losses of an emergency system considering the connections between the components of the system, contributing, in an original way, to the estimation of the seismic effects. The fundamental characteristics of this calculation are: • Estimating ground motion amplification at the territorial scale using a Vs30 from a probabilistic map obtained with the seismic microzonation national database; • Estimating shaking scenarios in terms of PGA and PGV depending on the Vs30; • Co-seismic permanent failure and deformations (landslide and liquefaction) evaluated with regression logistic methods. Finally, a case study is presented showing the application of the methodology on a real emergency system in an area of southern Italy. Stochastic evaluation of structural emergency system of a Territorial Context (TCSO index). Stochastic evaluation of seismic hazard with spatial correlation ground motion fields. Probabilistic Vs30 map from Seismic Microzonation Databe (DBMS). Coseismic effects for landslide and liquefaction triggered for any realization of stochastic base hazard. [ABSTRACT FROM AUTHOR]

Earthquake surface fault ruptures can show very complex geometries and involve different faults simultaneously. Consequently, modern fault-based probabilistic seismic hazard assessments (PSHA) need to account for such complexities in order to achieve more realistic modellings that treat fault systems as a whole and consider the occurrence of earthquake ruptures as aleatory uncertainties. We use SHERIFS, a recent approach of modelling annual rates of complex multi-fault ruptures, to obtain system-level magnitude-frequency distributions (MFDs) for the Eastern Betics Shear Zone (EBSZ, Spain) considering four fault rupture hypotheses. We then analyze the consistency of each scenario based on data from the earthquake catalogue and paleoseismic studies. The definition of the different rupture hypotheses was discussed within the frame of Fault2SHA ESC working group and critical fault input data is extracted from previous published studies. The four rupture hypotheses are defined as incremental scenarios based on fault geometry and kinematics, with lengths varying from minimal fault sections to a rupture of nearly the whole system. The results suggest that multi-fault ruptures involving lengths up to single to several whole faults are consistent with the annual rates from both the instrumental catalogue and paleoseismic record. The method does not allow to completely discard any hypothesis, but it allows to weight the different models in a logic tree for seismic hazard assessment. The approach is revealed as a practical tool for obtaining fault-system MFDs and as a useful tool for highlighting limitations and uncertainties in geological and paleoseismic data to be assessed. This study aims to constitute a step forward in the consideration of complex multi-fault ruptures for future seismic hazard assessments in the region. Unlabelled Image • Probabilistic seismic hazard assessments should model faults at a system scale. • Multi-fault ruptures should be considered in fault source modelling for PSHA. • Multi-fault ruptures are consistent with seismic and paleoseismic data at the EBSZ. • Epistemic uncertainties in fault databases have high impact in source modelling. • Constraining fault slip rates is primordial for fault-based PSHA models. [ABSTRACT FROM AUTHOR]

The identification of capable faults is crucial for reliable seismic hazard assessments. To identify geochemical signatures characterizing recent, near-surface faulting, we analyzed the mineral and bulk-rock compositions of a range of fault rocks. We compare the compositions of two faults in central Japan that displace the same granitic unit, but record distinct geological histories: the capable Shiraki–Nyu Fault and a minor, incapable fault. Brownish gouge along the Shiraki–Nyu Fault (representing the principal slip surface) records MnO enrichment and FeO depletion and has a positive Ce anomaly, which was likely produced through oxidation reactions. Compositional mapping of outcrop and core samples from the Shiraki–Nyu Fault indicates that compositional changes (Mn- and Fe-oxide and/or oxyhydroxide precipitation along the principal slip surface) were driven by the fault-driven upward migration and oxidation of reduced fluids from depth to the near-surface. Mapping also indicates that Mn-rich gouge (and ultracataclasite) has undergone brecciation due to recent shallow-level faulting. In the Mn-rich gouge, Ce, Ba, and Y may have been enriched through co-precipitation and/or sorption onto the Mn oxide surfaces. Pale gray gouge from the principal slip surface of the minor incapable fault records no oxidation-related chemical changes. However, anastomosing/grid-like fractures filled with dark gray clay, which cut the pale gray gouge yield elevated MnO and Ba concentrations, low FeO concentrations and positive Ce anomalies, as well as high halloysite abundances. These chemical changes are attributed to post-faulting infiltration of oxidized surface water rather than repeated faulting. We show that geochemical analysis, combined with detailed geological observations, can be used to determine the spatial distributions of elements in heterogeneous fault zones, and contribute to the identification of recent, near-surface faulting events. • Chemical changes due to oxidation of upward migrated reduced fluids were detected. • The oxidation reaction prevails along a principal slip surface of a capable fault. • Geochemical analysis for fault rocks can contribute to identifying capable faults. [ABSTRACT FROM AUTHOR]

This paper presents the results of numerical modeling of seismic site effects in a shallow estuarine bay (Suai Bay, Shantou, China), which is meaning for seismic hazard assessment and mitigation of estuarine and coastal structures, such as immersed tunnels, pipelines, caissons and breakwaters. The subsurface stratum and soil properties in the study area are obtained from geological and geotechnical surveys. Large-scale 2D finite-element refined nonlinear modeling is used to simulate ground motion for near-field and far-filed input motions with different design earthquake levels. The results show that for the study area: (1) The spatial distribution of PGA amplification factor presents obvious vertical and horizontal variations and is strongly affected by the overall geometry of interfaces of different materials. (2) The attenuation in soft sediments have significant influences on surface ground motion, which leads to a deamplification of the acceleration amplitude, a prolongation of the significant duration and a filtration of the high-frequency spectral content. (3) The PGA alone cannot be regarded as an adequate parameter to quantify nonlinear site effects, while the energy content (expressed by Arias intensity) is more closely related to transfer functions patterns. (4) The seismic intensity at surface is greater than the intensity of input motion during weak motions, while the seismic intensity at surface is smaller than the intensity of input motion during strong motions, suggesting that isolation effects may be expected in the areas having thick soft soils with a low plasticity index during strong motions. • Seismic site effects in a shallow estuarine bay is modeled by finite element method. • Borehole records from vertical seismic arrays are selected as the input motions. • Nonlinear site effects are closely related to the energy content of input motions. • Thick soft sediments with low PI act as an isolation system during strong motions. [ABSTRACT FROM AUTHOR]