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The paper addresses the issue of estimating the coefficients of the sotolongo-costa and posadas (SCP) model in the presence of uncertain earthquake magnitude data. The SCP model offers a more accurate representation of regional seismicity compared to the traditional Gutenberg–Richter (G-R) law and has been integrated into the probabilistic seismic hazard analysis (PSHA) framework as NEPSHA. The study aims to develop a method to calculate the SCP coefficients in the presence of uncertain magnitude data, implement the process in R programming language, and validate its effectiveness through a case study. The methodology involves developing the mathematical relationship for estimating the SCP parameters using maximum likelihood estimation (MLE) and modifying the MLE approach to account for magnitude uncertainty. The method is tested using simulated earthquake catalogs with varying degrees of magnitude uncertainty. The results demonstrate that the proposed method can alter the estimated values of the SCP parameters, particularly the a value, by approximately 50% when magnitude uncertainty is considered. The q variable is found to be less affected by the estimation method. [ABSTRACT FROM AUTHOR]

To secure the seismic performance of structures, seismic risk assessment is necessary to quantify safety against beyond-design-based earthquakes and seismic design. For the seismic risk assessment of structures, the input ground motions corresponding to the seismic intensity for evaluation are required as seismic loads, which must reflect the tectonic characteristics and site conditions. In this study, ground motions recorded in regions of low to moderate seismicity were used to generate examples of input ground motions for seismic risk assessment. A uniform hazard spectrum (UHS) was used as the target spectrum for risk assessment, following the guidelines. The magnitude and distance parameters of the scenario earthquake for seismic risk assessment were determined via hazard de-aggregation. The empirical Green's function method (EGFM) was used to match the ground motion recorded at the site with the seismic intensity required for seismic risk assessment. In addition, a spectral matching process was applied to ensure that the input ground motion was compatible with the response spectrum used in seismic risk assessment. In this process, the convergence characteristics of the spectral matching to the target spectrum were analyzed. Consequently, the spectral conditions for selecting the ground motion for the seismic risk assessment were determined. [ABSTRACT FROM AUTHOR]

In this study, a multi-source data fusion method was proposed for the development of a Hybrid seismic hazard model (HSHM) in China by using publicly available data of the 5th Seismic Ground Motion Parameter Zoning Map (NSGM) and historical seismic catalogues and integrating with modern ground motion prediction equations (GMPEs). This model incorporates the characteristics of smoothed seismicity and areal sources for regional seismic hazard assessment. The probabilistic seismic hazard for the North China Plain earthquake belt was investigated through sensitivity analysis related to the seismicity model and GMPEs. The analysis results indicate that the Hybrid model can produce a consistent result with the NSGM model in many cases. However, the NSGM model tends to overestimate hazard values in locations where no major events have occurred and underestimate hazard values in locations where major events have occurred. The Hybrid model can mitigate the degree of such biases. Compared to the modern GMPEs, the GMPE with epicentral distance measures significantly underestimate the seismic hazard under near-field and large-magnitude scenarios. In addition, a comparison of the uniform hazard spectra (UHS) obtained by the models, with China's design spectrum, shows that the current design spectrum is more conservative than the calculated UHS. [ABSTRACT FROM AUTHOR]

Abstract In this study, a multi-source data fusion method was proposed for the development of a Hybrid seismic hazard model (HSHM) in China by using publicly available data of the 5th Seismic Ground Motion Parameter Zoning Map (NSGM) and historical seismic catalogues and integrating with modern ground motion prediction equations (GMPEs). This model incorporates the characteristics of smoothed seismicity and areal sources for regional seismic hazard assessment. The probabilistic seismic hazard for the North China Plain earthquake belt was investigated through sensitivity analysis related to the seismicity model and GMPEs. The analysis results indicate that the Hybrid model can produce a consistent result with the NSGM model in many cases. However, the NSGM model tends to overestimate hazard values in locations where no major events have occurred and underestimate hazard values in locations where major events have occurred. The Hybrid model can mitigate the degree of such biases. Compared to the modern GMPEs, the GMPE with epicentral distance measures significantly underestimate the seismic hazard under near-field and large-magnitude scenarios. In addition, a comparison of the uniform hazard spectra (UHS) obtained by the models, with China’s design spectrum, shows that the current design spectrum is more conservative than the calculated UHS.

Seismic hazard maps have been developed for the Faizabad region of Uttar Pradesh state of India, utilizing deterministic and probabilistic methodologies. Maximum earthquake magnitudes were meticulously determined for each seismic source within a 500 km radius, considering region-specific seismotectonic parameters and rupture characteristics. Twenty-seven ground motion prediction equations were considered for the studied regions, and through an efficacy test, ground motion prediction equations (GMPEs) were selected for segmented hypocentral distances. The final hazard values were computed by applying varied weighting factors to the chosen GMPEs. The peak ground acceleration (PGA) and spectral acceleration (SA) were computed for 2 and 10% probabilities of exceedance in 50 years. The PGA values for the region were found to range between 0.01 and 0.14 g, as obtained from the deterministic analyses. It was inferred from the PSHA that the PGA values range between 0.05 to 0.20 g and 0.01 to 0.12 g for the 2 and 10% probability of exceedance, respectively, for 50 years. Blocks situated in the southeastern part of the city, encompassing Gonda, Faizabad Sultanpur, and Pratapgarh, have been singled out as particularly vulnerable to seismic hazards, thus warranting heightened attention and strategic planning in urban and infrastructure development. [ABSTRACT FROM AUTHOR]

With the rapid development of energy-based seismic design, probabilistic seismic hazard analysis (PSHA) in terms of the input energy spectrum, E I , has become increasingly important. Generally, implementing E I -based PSHA requires a ground-motion prediction equation (GMPE) for E I . However, although a GMPE for E I can be constructed in regions with abundant earthquake data based on regression analyses, it is difficult to obtain in regions lacking strong ground-motion records. Therefore, this study proposes a new approach for performing E I -based PSHA in regions with limited earthquake data. Instead of using a GMPE for E I directly, a model of Fourier amplitude spectrum (FAS) is adopted, which can be determined using a small number of earthquake data with small-to-moderate magnitudes. Then, the E I of the ground motion is obtained from FAS based on the relationship between E I and FAS. Furthermore, to calculate the annual intensity exceedance rate within the proposed framework of adopting the FAS model, a highly efficient method, namely, the moment method, is applied. Several numerical examples indicate that the proposed approach not only is suitable for regions lacking strong ground-motion records but also performs very efficiently in calculating the annual intensity exceedance rate. [ABSTRACT FROM AUTHOR]

Damages caused by possible earthquake scenarios are predicted by earthquake engineers. To determine the performance of water distribution systems after an earthquake scenario, there is a need for network reliability analysis. While performing earthquake hazard analysis, defining the seismic vulnerability model, and estimating the probability of pipeline failure, the study discusses the effects of various earthquake scenarios on pipeline reliability. The innovation of the study is the inclusion of the results of the Probabilistic Seismic Hazard Analysis (PSHA) in the reliability analysis and the investigation of the seismic performance of the pipelines according to various probabilistic methods. The results emphasize the use of Monte Carlo method in estimating the reliability of lifelines, and the need to consider two or more focal earthquakes in estimating the vulnerability of water distribution systems. [ABSTRACT FROM AUTHOR]

The Coimbatore corporation area is comprised of very densely occupied residential and commercial buildings which are prone to future earthquakes. Probabilistic Seismic Hazard Analysis (PSHA) was carried out for the study region using the Classical Cornell approach and the logic-tree approach. A combination of 45 linear/fault sources and an areal source with a 500 km radius has been considered for the study. An updated earthquake catalogue has been compiled from various works of literature and authorized organizations. The collected earthquake catalogue of various magnitude scales has been homogenized into a uniform moment magnitude scale M w . Fore-shocks and after-shocks have been removed from independent events using one of the declustering algorithms. The seismicity parameters have been evaluated using the Guttenberg–Richter recurrence law. A hybrid GMPE composed of three attenuation relationships was used to obtain the ground motion parameters for the study region. The contour maps of Peak Ground Acceleration (PGA) and Peak Spectral Acceleration (PSA) for the bed-rock condition have been presented in terms of 10 and 2% Probability of Exceedance (PoE) for the return period of 475 and 2475 yr, respectively. The Uniform Hazard Response Spectra (UHRS) for Coimbatore city has been compared with (IS 1893-I-(2016) Criteria for earthquake resistant design of structures. Part 1: General provisions and buildings; Bureau of Indian Standards). As a result of deaggregation, the predominant hazard has been found within a 100 km distance and no hazards have been observed from a long distance as a controlling scenario from the analysis. [ABSTRACT FROM AUTHOR]

In this study, a probabilistic seismic hazard analysis (PSHA) using a traditional approach with a simple logic tree that handles a single-site sigma is developed to present a site-specific ground motion hazard. The analysis relies on the accelerometer data collected from the I-Lan Plain, a deep sedimentary basin in Northeastern Taiwan where hundreds of earthquake sequences (with M w = 4.0–7.6) were recorded by the Taiwan Strong Motion Instrument Program (TSMIP) network between 1992 and 2016. The performance of PSHA on soil and hard sites is evaluated from two representative instrumented sites (ILA048 and ILA025), using residual measures available from a ground motion model (GMM) developed by Phung et al. [2023] (referred to as Ph23), from which the uncertainties in site terms ( δ S 2 S s) and single-site sigma ( σ S S , S) are estimated. We address key conceptual issues in the current PSHA approach and introduce a new region- and site-specific PSHA approach in which (1) site-to-site variability ( ϕ S 2 S) is estimated as a random variance in a mixed effects GMM regression and (2) the GMM site-specific single-site sigma ( σ S S , S) is replaced with a generic site-corrected aleatory variability ( σ 0 ). Comparison of the region- and site-specific hazard curves from our method against the traditional method estimates at two well-recorded sites in the I-Lan region shows an approximate 50% difference in prediction ground motion values considering for 2% and 10% probability of exceedance in 50 years. [ABSTRACT FROM AUTHOR]

Seismic analysis is very important along with the development as well as the spatial and territorial layout of an area. However, unfortunately, the development of Indonesia's latest national earthquake hazard map still uses the 2017 earthquake database, not yet the latest seismic hazard catalog. This study presents an analysis using a new Probabilistic Seismic Hazard (PSHA) in the Java region, especially Surabaya, which is contains a very complex tectonic region. The Probabilistic Seismic Hazard Analysis (PSHA) includes active faults, megathrust and intraplate subduction, as well as an updated background earthquake source database and attenuation equation. The logic tree method was used to quantify the epistemic uncertainty of the source parameter components. This research calculates the bedrock Peak Ground Acceleration (PGA) with a 2475-year return period for the greater Surabaya area, which has the greatest concentrations of population and business in East Java. The analysis shows the seismic hazard is dominated by the background source in the Surabaya area. The result of this study may be useful for updating the hazard map and attracting the interest of researchers to conduct research related to seismic hazards, especially in the Surabaya area. [ABSTRACT FROM AUTHOR]

To secure the seismic performance of structures, seismic risk assessment is necessary to quantify safety against beyond-design-based earthquakes and seismic design. For the seismic risk assessment of structures, the input ground motions corresponding to the seismic intensity for evaluation are required as seismic loads, which must reflect the tectonic characteristics and site conditions. In this study, ground motions recorded in regions of low to moderate seismicity were used to generate examples of input ground motions for seismic risk assessment. A uniform hazard spectrum (UHS) was used as the target spectrum for risk assessment, following the guidelines. The magnitude and distance parameters of the scenario earthquake for seismic risk assessment were determined via hazard de-aggregation. The empirical Green’s function method (EGFM) was used to match the ground motion recorded at the site with the seismic intensity required for seismic risk assessment. In addition, a spectral matching process was applied to ensure that the input ground motion was compatible with the response spectrum used in seismic risk assessment. In this process, the convergence characteristics of the spectral matching to the target spectrum were analyzed. Consequently, the spectral conditions for selecting the ground motion for the seismic risk assessment were determined.

Synchronous rupture involving two or more antithetic or synthetic faults results in higher levels of ground shaking hazard compared to that computed separately for each fault. We describe methodologies to estimate the ground motions both deterministically and probabilistically using a square-root-sum-of-the-squares approach and provide a case study for the Salt Lake City segment of the Wasatch fault zone and the antithetic West Valley fault zone in the Salt Lake Valley, Utah. The amount of increased hazard between the fault pairs will depend on their fault dips and horizontal separation which will dictate their potential rupture areas and hence their maximum magnitudes. For the case study, the increased hazard between the Salt Lake City segment and the West Valley fault zone can range up to 30% primarily at short to moderate periods (<1 s). [ABSTRACT FROM AUTHOR]

Quantitative assessments of seismic hazard in seismically active areas depend to a large extent on the intensity-distance attenuation laws which are used in calculations. To account for epistemic uncertainty in the nature of seismic effects, it is recommended to perform probabilistic seismic hazard analysis using several different attenuation relationships. The most effective tool for their selection is the ranking procedure which consists in attributing a weight to one or another equation depending on the degree of compliance between the equation-based seismic effects and the real experimental data available for the region under study. The article presents the results of ranking intensity attenuation laws derived for Central Asia. Ranking was carried out by LH and LLH methods. Based on the ranking results, these has been made a generalized attenuation model used subsequently in PSHA for Uzbekistan. Consideration was given to three alternative models of seismic sources: area sources, active faults, and seismogenic zones. Parameterization of the models considered involved determining seismic potential, frequency of recurrence of earthquakes of different energy levels, and the predominant type of motions in each earthquake source. Seismic zoning maps of Uzbekistan in points of the MSK-64 intensity scale have been compiled for different probabilities of occurrence of non-exceedance level earthquakes in the next 50 years.

Abstract The estimated seismic hazard based on the delineated seismic source model is used as the basis to assign the seismic design loads in Canadian structural design codes. An alternative for the estimation is based on a spatially smoothed source model. However, a quantification of differences in the Canadian seismic hazard maps (CanSHMs) obtained based on the delineated seismic source model and spatially smoothed model is unavailable. The quantification is valuable to identify epistemic uncertainty in the estimated seismic hazard and the degree of uncertainty in the CanSHMs. In the present study, we developed seismic source models using spatial smoothing and historical earthquake catalogue. We quantified the differences in the estimated Canadian seismic hazard by considering the delineated source model and spatially smoothed source models. For the development of the spatially smoothed seismic source models, we considered spatial kernel smoothing techniques with or without adaptive bandwidth. The results indicate that the use of the delineated seismic source model could lead to under or over-estimation of the seismic hazard as compared to those estimated based on spatially smoothed seismic source models. This suggests that an epistemic uncertainty caused by the seismic source models should be considered to map the seismic hazard.

The Statewide (formerly Southern) California Earthquake Center (SCEC) conducts multidisciplinary earthquake system science research that aims to develop predictive models of earthquake processes, and to produce accurate seismic hazard information that can improve societal preparedness and resiliency to earthquake hazards. As part of this program, SCEC has developed the CyberShake platform, which calculates physics-based probabilistic seismic hazard analysis (PSHA) models for regions with high-quality seismic velocity and fault models. The CyberShake platform implements a sophisticated computational workflow that includes over 15 individual codes written by 6 developers. These codes are heterogeneous, ranging from short-running high-throughput serial CPU codes to large, long-running, parallel GPU codes. Additionally, CyberShake simulation campaigns are computationally extensive, typically producing tens of terabytes of meaningful scientific data and metadata over several months of around-the-clock execution on leadership-class supercomputers. To meet the needs of the CyberShake platform, we have developed an extreme-scale workflow stack, including the Pegasus Workflow Management System, HTCondor, Globus, and custom tools. We present this workflow software stack and identify how the CyberShake platform and supporting tools enable us to meet a variety of challenges that come with large-scale simulations, such as automated remote job submission, data management, and verification and validation. This platform enabled us to perform our most recent simulation campaign, CyberShake Study 22.12, from December 2022 to April 2023. During this time, our workflow tools executed approximately 32,000 jobs, and used up to 73% of the Summit system at Oak Ridge Leadership Computing Facility. Our workflow tools managed about 2.5 PB of total temporary and output data, and automatically staged 19 million output files totaling 74 TB back to archival storage on the University of Southern California's Center for Advanced Research Computing systems, including file-based relational data and large binary files to efficiently store millions of simulated seismograms. CyberShake extreme-scale workflows have generated simulation-based probabilistic seismic hazard models that are being used by seismological, engineering, and governmental communities.

The utilization of the Monte Carlo method in conjunction with probabilistic seismic hazard analysis (PSHA) constitutes a compelling avenue for exploration. This approach presents itself as an efficient and adaptable alternative to conventional PSHA, particularly when confronted with intricate factors such as parameter uncertainties and diverse earthquake source models. Leveraging the Monte Carlo method and drawing from the widely adopted Cornell-type seismicity model in engineering seismology and disaster mitigation, as well as a seismicity model capturing temporal, spatial, and magnitude inhomogeneity, we have derived a formula for the probability of earthquake intensity occurrence and the mean rate of intensity occurrence over a specified time period. This effort has culminated in the development of a MATLAB-based program named MCPSHA. To assess the model's efficacy, we selected Baoji City, Shaanxi Province, China, as our research site. Our investigation delves into the disparity between occurrence probability and extreme probability (a surrogate commonly employed for occurrence probability) in the Baoji region over the next 50 years. The findings reveal that the Western region of Baoji exhibits a heightened hazard level, as depicted in the maps, which illustrate a 10% probability of exceedance within a 50-year timeframe. The probability of earthquake occurrence under various intensities (VI, VII, and VIII) over 50 years follows a declining trend from west to east. Furthermore, the likelihood of seismic intensity exceeding VI, VII, and VIII indicates the lowest exceeding probability in the northeast and the highest in the northwest. Notably, for intensities VI-VII, the difference between occurrence probability and extreme probability approaches twice, gradually diminishing with increasing intensity. This study underscores the MCPSHA model's efficacy in providing robust technical support for mitigating earthquake risk and enhancing the precision of earthquake insurance premium rate calculations. [ABSTRACT FROM AUTHOR]

In many countries, seismic characterization of the site selected for a critical structure or industrial facility is required in terms of site-specific seismic ground motion hazard. For this purpose, a probabilistic seismic hazard analysis (PSHA), performed under the Senior Seismic Hazard Analysis Committee (SSHAC) protocol, is an extended practice for nuclear facilities. In the past decade, SSHAC Level 3 studies have been performed for sites in North America, Europe, Japan, Taiwan, and South Africa. When analyzing PSHA results, the mean-to-median spectral acceleration ratios given by the hazard curves can be interpreted as a measure of the degree of epistemic uncertainty associated with the results. In this article, results of 33 SSHAC Level 3 studies have been used to determine mean-to-median spectral acceleration ratios and the statistics of these ratios, as a function of spectral frequency and annual frequency of exceedance (AFE). The purpose was to develop a reference for the range of uncertainty that is typically captured in this kind of studies. It has been found that, for a given AFE, ratios corresponding to different sites are within a relatively small interval, especially for the spectral frequency band between 2.5 and 10 Hz, which is the band normally more relevant for the seismic design of nuclear installations. In this band, for 10−4 yr−1 AFE, a mean/median ratio of 1.40 would envelop practically all investigated sites. [ABSTRACT FROM AUTHOR]

With the improvement of the world's largest seafloor observation network (S-net) and the increase in the quantity and quality of records, the ergodic assumptions can be further relaxed in the modeling of offshore ground motion models (GMMs). This allows accounting for systematic and repeatable source, site, and path effects to further understand the characteristics of offshore ground motion in the Japan Trench region. We developed an offshore ergodic backbone GMM for subduction earthquakes and classified the sites into four categories using horizontal–vertical response spectral ratio to investigate site amplification. The offshore ergodic GMM is applicable for subduction earthquake scenarios with moment magnitudes ranging from 4.0 to 7.4 and rupture distances ranging from 10 to 300 km. Comparing offshore ergodic GMMs with onshore GMMs for subduction earthquakes, we found that offshore GMMs were significantly different from onshore GMMs, especially in the long-period and unburied states. Then a new offshore non-ergodic GMM was developed based on the offshore ergodic GMM. The systematic and repeatable source and site effects were captured by the spatially varying coefficients represented by Gaussian processes, while the systematic and repeatable path effects were captured by cell-specific anelastic attenuation proposed by Dawood and Rodriguez-Marek (2013), calculated with the Cohen-Sutherland computer graphics algorithm. The non-ergodic GMM revealed systematic and repeatable source, site, and path effects that were not captured by the ergodic GMM. Moreover, the non-ergodic GMM showed reduced aleatory variability and epistemic uncertainty on ground motion estimation compared to ergodic GMM. The reduction of aleatory variability and epistemic uncertainty had a significant impact on probabilistic seismic hazard analysis. Quantifications of these results are contributed to conduct reasonable seismic design and seismic risk assessment for marine engineering in offshore regions vulnerable to strong subduction earthquakes. [ABSTRACT FROM AUTHOR]

The estimated seismic hazard based on the delineated seismic source model is used as the basis to assign the seismic design loads in Canadian structural design codes. An alternative for the estimation is based on a spatially smoothed source model. However, a quantification of differences in the Canadian seismic hazard maps (CanSHMs) obtained based on the delineated seismic source model and spatially smoothed model is unavailable. The quantification is valuable to identify epistemic uncertainty in the estimated seismic hazard and the degree of uncertainty in the CanSHMs. In the present study, we developed seismic source models using spatial smoothing and historical earthquake catalogue. We quantified the differences in the estimated Canadian seismic hazard by considering the delineated source model and spatially smoothed source models. For the development of the spatially smoothed seismic source models, we considered spatial kernel smoothing techniques with or without adaptive bandwidth. The results indicate that the use of the delineated seismic source model could lead to under or over-estimation of the seismic hazard as compared to those estimated based on spatially smoothed seismic source models. This suggests that an epistemic uncertainty caused by the seismic source models should be considered to map the seismic hazard. [ABSTRACT FROM AUTHOR]

AbstractThe greater Jakarta area is located in west Java and has a high earthquake risk due to the subduction of the Australian Plate beneath the Eurasian Plate. Previous hazard studies have been carried out using various seismic probability approaches. This study presents a new probabilistic seismic hazard analysis (PSHA) by developing an updated seismic model for the crustal active fault database, using a new set of ground motion prediction equations (GMPE), and taking into consideration the effect of site amplification. The logic tree method was used to quantify the epistemic uncertainty of the source parameter components and the attenuation equation was used. We calculate the peak ground acceleration (PGA) and spectral acceleration (SA) for West Java, including metropolitan Jakarta, Bogor and Serang, which have the greatest concentrations of population and business. We found that the mean PGA reaches 1.0 g or a 2% probability of exceedance in 50 years, including site amplification factors. The seismic hazard is dominated by the shallow crustal fault near metropolitan Jakarta. The result of this study may be useful for updating the existing Indonesian hazard map.

The RINTC (2015–2017) project was a three-year research program aimed at assessing the seismic reliability of code-conforming structures in Italy. It dealt with five structural typologies of residential and industrial buildings: reinforced concrete, masonry, precast reinforced concrete, steel, and base isolated reinforced concrete. To reach its goals, several tens of structures featuring the same configuration were designed at different sites, characterized by different seismic hazard and considering two soil site conditions. The failure risk (i.e. the failure rate) of the buildings was evaluated by means of non-linear dynamic analysis of three-dimensional numerical models. The study herein presented parametrized the vulnerability models of the considered structures; in other words, it provides the seismic fragility curves for code-conforming Italian buildings analyzed in the RINTC project. Lognormal fragilities refer to global collapse failure and usability preventing damage, which are the performances considered in the project, and are derived via state-of-the-art methods, including consideration of the uncertainty in the estimation of their parameters. The curves are made available to be possibly used for further risk analyses and enable a discussion of the fragility fitting issues as a function on the site's hazard. [ABSTRACT FROM AUTHOR]

This paper provides an overview and introduction to the development of non-ergodic ground-motion models, GMMs. It is intended for a reader who is familiar with the standard approach for developing ergodic GMMs. It starts with a brief summary of the development of ergodic GMMs and then describes different methods that are used in the development of non-ergodic GMMs with an emphasis on Gaussian process (GP) regression, as that is currently the method preferred by most researchers contributing to this special issue. Non-ergodic modeling requires the definition of locations for the source and site characterizing the systematic source and site effects; the non-ergodic domain is divided into cells for describing the systematic path effects. Modeling the cell-specific anelastic attenuation as a GP, and considerations on constraints for extrapolation of the non-ergodic GMMs are also discussed. An updated unifying notation for non-ergodic GMMs is also presented, which has been adopted by the authors of this issue. [ABSTRACT FROM AUTHOR]

A new approach for creating a non-ergodic pseudo-spectral acceleration (PSA) ground-motion model (GMM) is presented, which accounts for the magnitude dependence of the non-ergodic effects. In this approach, the average PSA scaling is controlled by an ergodic PSA GMM, and the non-ergodic effects are captured with non-ergodic PSA factors, which are the adjustment that needs to be applied to an ergodic PSA GMM to incorporate the non-ergodic effects. The non-ergodic PSA factors are based on the effective amplitude spectrum (EAS) non-ergodic effects and are converted to PSA through Random Vibration Theory (RVT). The advantage of this approach is that it better captures the non-ergodic source, path, and site effects through small-magnitude earthquakes. Due to the linear properties of the Fourier Transform, the EAS non-ergodic effects of the small events can be applied directly to the large magnitude events. This is not the case for PSA, as response spectra are controlled by a range of frequencies, making PSA non-ergodic effects dependent on the spectral shape, which in turn is magnitude-dependent. Two PSA non-ergodic GMMs are derived using the ASK14 (Abrahamson et al. in Earthq Spectra 30:1025–1055, 2014) and CY14 (Chiou and Youngs in Earthq Spectra 30:1117–1153, 2014) GMMs as backbone models, respectively. The non-ergodic EAS effects are estimated with the LAK21 (Lavrentiadis et al. in Bull Earthq Eng) GMM. The RVT calculations are performed with the V75 (Vanmarcke in ASCE Mech Eng Mech Division 98:425–446, 1972) peak factor model, the D a 0.05 - 0.85 estimate of AS96 (Abrahamson and Silva in Apendix A: empirical ground motion models, description and validation of the stochastic ground motion model. Tech. rep.,. Brookhaven National Laboratory, New York) for the ground-motion duration, and BT15 (Boore and Thompson in Bull Seismol Soc Am 105:1029–1041, 2015) oscillator-duration model. The California subset of the NGAWest2 database (Ancheta et al. in Earthq Spectra 30:989–1005, 2014) is used to fit both models. The total aleatory standard deviation of each of the two non-ergodic PSA GMMs is approximately 25 % smaller than the total aleatory standard deviation of the corresponding ergodic PSA GMMs. This reduction has a significant impact on hazard calculations at large return periods. In remote areas, far from stations and past events, the reduction of aleatory variability is accompanied by an increase in epistemic uncertainty. [ABSTRACT FROM AUTHOR]

A new non-ergodic ground-motion model (GMM) for effective amplitude spectral (EAS) values for California is presented in this study. EAS, which is defined in Goulet et al. (Effective amplitude spectrum (eas) as a metric for ground motion modeling using fourier amplitudes, 2018), is a smoothed rotation-independent Fourier amplitude spectrum of the two horizontal components of an acceleration time history. The main motivation for developing a non-ergodic EAS GMM, rather than a spectral acceleration GMM, is that the scaling of EAS does not depend on spectral shape, and therefore, the more frequent small magnitude events can be used in the estimation of the non-ergodic terms. The model is developed using the California subset of the NGAWest2 dataset (Ancheta in PEER NGA-West2 database. Tech. rep., PEER, Berkeley, CA, 2013). The Bayless and Abrahamson (Bull Seismol Soc Am 109(5): 2088-2105, https://doi.org/10.1785/0120190077, 2019b) (BA18) ergodic EAS GMM was used as backbone to constrain the average source, path, and site scaling. The non-ergodic GMM is formulated as a Bayesian hierarchical model: the non-ergodic source and site terms are modeled as spatially varying coefficients following the approach of Landwehr et al. (Bull Seismol Soc Am 106(6):2574-2583. https://doi.org/10.1785/0120160118, 2016), and the non-ergodic path effects are captured by the cell-specific anelastic attenuation attenuation following the approach of Dawood and Rodriguez-Marek (Bull Seismol Soc Am 103(2B):1360-1372, https://doi.org/10.1785/0120120125, 2013). Close to stations and past events, the mean values of the non-ergodic terms deviate from zero to capture the systematic effects and their epistemic uncertainty is small. In areas with sparse data, the epistemic uncertainty of the non-ergodic terms is large, as the systematic effects cannot be determined. The non-ergodic total aleatory standard deviation is approximately 30 to 40 % smaller than the total aleatory standard deviation of BA18. This reduction in the aleatory variability has a significant impact on hazard calculations at large return periods. The epistemic uncertainty of the ground motion predictions is small in areas close to stations and past events. [ABSTRACT FROM AUTHOR]

A novel methodology for obtaining a seismic zone map of India is demonstrated in this study, wherein a concrete theoretical framework is provided for deriving the zones and the respective zonal response spectra. The method involves time series clustering of uniform hazard response spectra (UHRS) that were obtained for the entire country on a 0.1° × 0.1° grid by performing probabilistic analysis corresponding to a 2475-year return period. The Euclidean distance between the UHRS values at all periods (27 data points between 0.01 s and 5 s) was taken as the similarity measure in an evolutionary particle swarm optimization algorithm. The analysis was conducted with a swarm population of 100 over 3000 iterations, and the mean UHRS of the resulting clusters was assumed as the cluster centre. Various quality/validity indices including the compactness measure, similarity measure, combined measure and Dunn Index were used to verify the results of the clustering. Based on these clusters, the entire country can be divided into seven zones, with a unique zonal spectrum for each zone. [ABSTRACT FROM AUTHOR]

This article presents updated seismic hazard curves, spectra, and maps of ground motion intensity measures for the northern region of the Dominican Republic (DR) obtained using a probabilistic seismic hazard analysis (PSHA). The analysis performed uses as input data an earthquake recurrence model based on fault slip rates derived from GPS measurements published in the aftermath of the 2010 Haiti earthquake. The seismicity rate data are used to calibrate a composite characteristic earthquake model, which is combined with a Poisson process to provide a temporal characterization of earthquake occurrence. The seismic hazard curves and maps presented include parameters such as (horizontal) peak ground acceleration and pseudo-spectral response accelerations at 0.2s and 1.0s periods for 5% damping at firm rock sites. The results show that the ground motion parameters with a 2% probability of exceedance (PE) in 50 years determined in this study are up to 46% larger than the corresponding parameters specified in the current DR building code seismic hazard maps for the northern DR. Moreover, the design response spectra for a site in the city of Santiago specified in the code is significantly lower than the 2% PE in 50 years uniform hazard spectra determined in this study for vibration periods smaller than 0.5s, a range that includes the majority of the structures that define the built environment of the DR. [ABSTRACT FROM AUTHOR]

In this study, a rectangular area surrounding Nepal, bounded by the coordinates (N 25° 30' 00", E 78° 30' 00"), (N 31° 30' 00", E 89 ° 30' 00") has been considered. Study area has been divided into five hundred areas by defining the grids at the interval of 0.5 degree along longitude and 0.25 degree along latitude. By preparing detailed earthquake catalogue and defining areal seismic sources, probabilistic seismic hazard analysis has been done in terms of peak ground acceleration. The completeness of the data has been done by using Stepp's procedure. Seismicity in four regions of study area has been evaluated by defining 'a' and 'b' parameters of Gutenberg Richter recurrence relationship. Average hazard spectrum for 10% probability of exceedence in fifty years in five percent damped condition is obtained and then normalized to obtain design spectra and seismic zoning factor 'Z' is obtained in terms of contour for all areas of Nepal. [ABSTRACT FROM AUTHOR]

We investigate probabilistic seismic hazard analysis (PSHA) in low-seismicity regions in which epistemic uncertainties are largely due to the sparsity of data, with a focus on Finland, northern Europe. We investigate the sensitivity of site-specific PSHA outcomes to different choices of basic input parameters, starting from preexisting PSHA models of the nuclear licensees in the country, without producing a final hazard curve. The outcome shows that the parameters and models needed to estimate future seismicity rates from actual observations, in particular the b value, seismicity rates, and the largest possible magnitude, Mmax, as well as the median ground-motion prediction equation, play significant roles. The sensitivity also depends on the spectral frequency; for example, the effect of Mmax is significant especially for a low-frequency hazard at annual frequency of exceedance 10−5 but more moderate for peak ground acceleration. The delineation of seismic source zones (SSZs) remains ambiguous in regions of low seismicity. This, combined with the dominance of the host SSZ and its seismicity parameters, may have a substantial impact on the outcome. Our results are quantitatively applicable to Finland, but may also be of relevance to other low-seismicity regions in Europe and elsewhere. For future work we recommend the exploration of PSHA sensitivity with focus on the host SSZ with its immediate vicinity and the b value around the site of interest. [ABSTRACT FROM AUTHOR]

The building code of any country is considered to be a basic technical guidance document for the seismic design of structures. However, building codes are typically developed for the whole country, without considering site specific models that incorporate detailed site-specific data. Therefore, the adequacy of the design spectrum for building codes may sometimes be questionable. To study the sufficiency of the building codes of Pakistan (BCP-SP-2007), a deterministic seismic hazard analysis (DSHA) based spectrum was developed for a site in the Muzaffargarh area, Pakistan, using an updated earthquake catalogue, seismic source model, and a next generation attenuation model (NGA-WEST-2). Further, an International Building Code (IBC-2000) spectrum was developed for the study area to compare the results. The DSHA-based response spectrum resulted in a peak ground acceleration (PGA) value of 0.21 g for the Chaudwan fault. The evaluation of BCP-SP-2007 and IBC-2000 spectra provided a critical assessment for analyzing the associated margins. A comparison with the DSHA-based response spectrum showed that the BCP-SP-2007 design spectrum mostly overlapped with the DSHA spectrum unlike IBC-2000. However, special attention is needed for designing buildings in the study area when considering earthquake periods longer than 1 s, and the BCP-SP-2007 spectrum can be enhanced when considering a period range of 0.12–0.64 s. Finally, BCP-SP-2007 is based on a probabilistic approach and its comparison with deterministic results showed the significance of both methods in terms of design.

The utilization of the Monte Carlo method in conjunction with probabilistic seismic hazard analysis (PSHA) constitutes a compelling avenue for exploration. This approach presents itself as an efficient and adaptable alternative to conventional PSHA, particularly when confronted with intricate factors such as parameter uncertainties and diverse earthquake source models. Leveraging the Monte Carlo method and drawing from the widely adopted Cornell-type seismicity model in engineering seismology and disaster mitigation, as well as a seismicity model capturing temporal, spatial, and magnitude inhomogeneity, we have derived a formula for the probability of earthquake intensity occurrence and the mean rate of intensity occurrence over a specified time period. This effort has culminated in the development of a MATLAB-based program named MCPSHA. To assess the model’s efficacy, we selected Baoji City, Shaanxi Province, China, as our research site. Our investigation delves into the disparity between occurrence probability and extreme probability (a surrogate commonly employed for occurrence probability) in the Baoji region over the next 50 years. The findings reveal that the Western region of Baoji exhibits a heightened hazard level, as depicted in the maps, which illustrate a 10% probability of exceedance within a 50-year timeframe. The probability of earthquake occurrence under various intensities (VI, VII, and VIII) over 50 years follows a declining trend from west to east. Furthermore, the likelihood of seismic intensity exceeding VI, VII, and VIII indicates the lowest exceeding probability in the northeast and the highest in the northwest. Notably, for intensities VI-VII, the difference between occurrence probability and extreme probability approaches twice, gradually diminishing with increasing intensity. This study underscores the MCPSHA model’s efficacy in providing robust technical support for mitigating earthquake risk and enhancing the precision of earthquake insurance premium rate calculations.

Kishanganj is the easternmost district in the Indian state of Bihar, which shares its international border with Nepal to the north and state border with West Bengal to the east. It is one of the most important trading hubs in the eastern Bihar region because of its closeness to the Nepal border. Kishanganj is situated close to the Indo-Eurasian thrust zone and has been affected by several devastating earthquakes in the past. Hence, it is indispensable to perform probabilistic seismic hazard analysis for the Kishanganj district. An earthquake catalogue of the past 300 yrs, consisting of earthquake events within a radius of 500 km from the center of Kishanganj, is considered for the estimation of bedrock level peak ground acceleration (PGA) values at 2% and 10% probability of exceedance in 50 yrs. Due to the absence of region-specific ground motion prediction equations (GMPEs), a logic-tree based approach consisting of four GMPEs is considered which resulted in a maximum expected PGAs of 0.39 and 0.17 g at 2% and 10% probability of exceedance in 50 yrs. Our results from seismic hazard maps reveal that the southern parts of the Kishanganj district and some eastern parts such as Pothia are most vulnerable to seismic hazard as they have high expected PGA values ranging between 0.36 and 0.39 g as per the MCE condition. Kishanganj district headquarter, i.e., Kishanganj city (0.33–0.39 g) and Kochadhamin (0.33–0.39 g) are found most vulnerable to seismic hazard while Terhagachh (0.28–0.31 g), Dighabank (0.30–0.29 g) and Thakurganj (0.25–0.35 g) are found to be least vulnerable. [ABSTRACT FROM AUTHOR]

The objective of this study is to ascertain the causes of damage to buildings that occurred due to an earthquake near its source, particularly in the Pleret sub-district in Yogyakarta Special Province Indonesia. This study was conducted because a large percentage of human fatalities and structural collapse occurred during the Yogyakarta earthquake of May 27, 2006. Since the earthquake records on the site are not available, another way to obtain synthetic ground motions can be done in ways suggested by Bulajic and Manic (Motion records as a seismological input for seismic safety evaluation engineering structures, 2005), Rezaeian and Kiureghian (Earthq Eng Struct Dyn 39:1155–1180, 2010). Towards these ends, this research applied the Total Probability Theorem in the Seismic Hazard Probability Analysis (PSHA) with 3-D seismic sources. In this case, the PSHA analysis was carried out based on a 10% probability exceeded for 50 years building life time. The obtained uniform hazard spectrum (UHS) was then transferred to the risk targeted Maximum Credible Earthquake MCEr through the directivity factor Df and risk targeted factor Rf with an average increase of 8.13% to UHS. Three earthquake records were selected, and after spectral matching, the high ranging bedrock accelerations were obtained from 0.254 to 0.289 g. After conducting site response analysis, peak ground accelerations on the ground surface varied from 0.398 to 0.412 g. Furthermore, acceleration site amplifications between 1.401 and 1.426 were obtained, which are higher than the spectral site amplification between 1.215 and 1.385. Since the site amplification is still in the normal category, building damage is mostly caused by relatively high levels of ground acceleration and shaking to relatively old buildings with low material and construction quality. Although the study is still in its early stages, there are indications of fling effects on the site even though the intensity is relatively small. [ABSTRACT FROM AUTHOR]

Offshore wind has become a major contributor to reducing global carbon emissions. This paper presents a probabilistic seismic hazard analysis for the Sofia Offshore Wind Farm, which is located about 200 km north-east of England in the southern North Sea and will be one of the largest offshore wind farms in the world once completed. The seismic source characterization is composed of two areal seismic source models and four seismic source models derived using smoothed gridded seismicity with earthquake catalogue data processed by different techniques. The ground motion characterization contains eight ground motion models selected based on comparisons with regional data. The main findings are (1) the variation in seismic hazard across the site is negligible; (2) the main source controlling the hazard is the source that includes the 1931 Dogger Bank earthquake; (3) earthquake scenarios controlling the hazard are Mw = 5.0–6.3 and R = 110–210 km; and (4) the peak ground accelerations on rock are lower than for previous regional studies. These results could help guide future seismic hazard assessments in the North Sea.

Probabilistic seismic hazard analyses (PSHA) require that at least the mean activity rate be known, as well as the distribution of magnitudes. Within the Gutenberg–Richter assumption, the magnitudes follow an exponential distribution which is upperly truncated to a maximum possible magnitude denoted m max . This parameter is often fixed from expert judgement under seismo-tectonic considerations, due to a lack of universal method. This paper proposes an alternative to the common Gutenberg Richter model based on the extreme value theory: it models the tail distribution of the magnitudes with a generalized Pareto distribution (GPD). To integrate this GPD model in a PSHA calculation for areas of low to moderate seimsicity, we propose the Randomized Gutenberg–Richter model: this is an innovative approach based on the usual exponential distribution where m max is randomized and follows a distribution defined from that previous GPD model. The inference process takes into account the time varying level of completeness of the catalogue and the uncertainty in the magnitude value itself. In order to quantify the impacts of the new model on the seismic hazard levels, we implemented it into a realistic probabilistic seismic hazard calculation. Results indicate that the Randomized Gutenberg–Richter model seems to be very useful for future PSHA models. This new recurrence model avoids having to fix a priori the maximum possible magnitude m max . This is particularly interesting as there is no widely accepted method to estimate that upper bound. [ABSTRACT FROM AUTHOR]