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This study highlights the continued need for numerical simulation methods to predict the earthquake response and damage of masonry mosques, despite recent advances in research. The Kamanlı Masonry Mosque in İzmir, Turkey was selected as a case study for this purpose. A probabilistic seismic hazard analysis was conducted using a uniform Poisson process model with 50-year probabilities of 2%, 10%, and 50%. Earthquakes from seismic sources were excluded based on time and distance, and the annual recurrence relationships of the source areas were determined using the least squares method. The non-linear response of a masonry mosque was investigated using the discrete element approach to study the impact of site conditions on its structural performance. Nonlinear dynamic analyses were conducted using records representing seismic events with 475- and 72-year return periods. The results indicated that the mosque is highly vulnerable to earthquakes, as the 475-year records resulted in significant damage and partial collapse. Damage indicators were employed to assess the response to the 72-year records, highlighting the most vulnerable areas that should be prioritized in any restoration efforts. [ABSTRACT FROM AUTHOR]

Kazakhstan is currently drafting new construction regulations that comply with the major provisions of the Eurocodes. Such regulations are created on the basis of seismic zoning maps of various degrees of detail, developed by our Institute of Seismology using a new methodological approach for Kazakhstan. The article is about creating the first normative map of the Detailed Seismic Zoning on a probabilistic foundation for the Republic of Kazakhstan's East Kazakhstan region. We carried out the probabilistic assessment of seismic hazard using a methodology consistent with the main provisions of Eurocode 8 and updated compared with that used in developing maps of Kazakhstan's General Seismic Zoning and seismic microzoning of Almaty. The most thorough and current data accessible for the area under consideration were combined with contemporary analytical techniques. Updates have been done to not only the databases being used but also the way seismic sources were shown, including active faults now. On a scale of 1:1000000, precise seismic zoning maps of the East Kazakhstan region were created for two probabilities of exceedance: 10 % and 2 % in 50 years in terms of peak ground accelerations and macroseismic intensities. The obtained seismic hazard distribution is generally consistent with the General Seismic Zoning of Kazakhstan's previous findings. However, because active faults were included and a thoroughly revised catalog was used, there are more pronounced zones of increased danger along the fault in the western part of the region. In the west of the territory, acceleration values also increased due to a more accurate consideration of seismotectonic conditions. Zoning maps are the basis for developing new state building regulations of the Republic of Kazakhstan.

Abstract Although Myanmar is an earthquake-prone country, there has not been proposed an official national seismic hazard map. Thus, this study conducted a probabilistic seismic hazard assessment for Myanmar and some of its metropolitan areas. Performing this assessment required a set of databases that incorporates both earthquake catalogs and fault parameters. We obtained seismic parameters from the International Seismological Centre, and the fault database includes fault parameters from paper reviews and the database. Based on seismic activities, we considered three categories of seismogenic sources—active fault source, shallow area source, and subduction zone source. We evaluated seismic activity of each source based on the earthquake catalogs and fault parameters. Evaluating the ground-shaking behaviors for Myanmar requires evaluation of ground-shaking attenuation; therefore, we validated existing ground motion prediction equations (GMPEs) by comparing instrumental observations and felt intensities for recent earthquakes. We then incorporated the best fitting GMPEs into our seismic hazard assessments. By incorporating the V s 30 (the average shear velocity down to 30 m depth) map from an analysis of topographic slope, we utilized site effect and assessed national probabilistic seismic hazards for Myanmar. The assessment shows highest seismic hazard levels near those faults with high slip rates, including the Sagaing Fault and along the Western Coast of Myanmar. We also assessed seismic hazard for some metropolitan cities, including Bagan, Bago, Mandalay, Sagaing, Taungoo and Yangon, in the forms of hazard curves and disaggregation by implementing detailed V s 30 maps from micro-tremor surveys. The city-scale assessments show higher hazards for sites close to an active fault or/and with a low V s 30, demonstrating the importance of investigating site conditions. The outcomes of this study will be beneficial to urban planning on a city scale and building code legislation on a national scale.

The results of the first project in Kazakhstan on the Detailed Seismic Zoning of regions on a new methodological basis are presented. The Probabilistic Seismic Hazard Assessment is carried out for the territories of East Kazakhstan (since 2022 EKO and Abay), Almaty (since 2022 Almaty and Zhetysu) and Zhambyl regions using a methodology consistent with the main provisions of Eurocode 8 and updated compared to that used in maps of the recent General Seismic Zoning of Kazakhstan territory. Modern methods and tools of analysis were used, as well as the most complete and up-to-date information available for the territories under consideration. The seismic source model included areal sources and active faults. The developed maps are discussed and hazard curves and uniform hazard spectra for the main cities in the considered regions are presented. The obtained results are generally consistent with the General Seismic Zoning but display some differences in PGA distribution due to including active faults and a comprehensively revised catalogue. Zoning maps will be the basis for the development of new state building regulations of the Republic of Kazakhstan. [ABSTRACT FROM AUTHOR]

Although Myanmar is an earthquake-prone country, there has not been proposed an official national seismic hazard map. Thus, this study conducted a probabilistic seismic hazard assessment for Myanmar and some of its metropolitan areas. Performing this assessment required a set of databases that incorporates both earthquake catalogs and fault parameters. We obtained seismic parameters from the International Seismological Centre, and the fault database includes fault parameters from paper reviews and the database. Based on seismic activities, we considered three categories of seismogenic sources—active fault source, shallow area source, and subduction zone source. We evaluated seismic activity of each source based on the earthquake catalogs and fault parameters. Evaluating the ground-shaking behaviors for Myanmar requires evaluation of ground-shaking attenuation; therefore, we validated existing ground motion prediction equations (GMPEs) by comparing instrumental observations and felt intensities for recent earthquakes. We then incorporated the best fitting GMPEs into our seismic hazard assessments. By incorporating the Vs30 (the average shear velocity down to 30 m depth) map from an analysis of topographic slope, we utilized site effect and assessed national probabilistic seismic hazards for Myanmar. The assessment shows highest seismic hazard levels near those faults with high slip rates, including the Sagaing Fault and along the Western Coast of Myanmar. We also assessed seismic hazard for some metropolitan cities, including Bagan, Bago, Mandalay, Sagaing, Taungoo and Yangon, in the forms of hazard curves and disaggregation by implementing detailed Vs30 maps from micro-tremor surveys. The city-scale assessments show higher hazards for sites close to an active fault or/and with a low Vs30, demonstrating the importance of investigating site conditions. The outcomes of this study will be beneficial to urban planning on a city scale and building code legislation on a national scale. [ABSTRACT FROM AUTHOR]

The seismogenic depth and seismic coupling are important inputs into seismic hazard estimates. Although the importance of seismic coupling is often overlooked, it significantly impacts seismic hazard results. We present an estimation of upper and lower seismogenic depth and hypocentral depth and seismic coupling in the transition zone between the Alps, Dinarides and Pannonian Basin, characterized by complex deformation pattern, highly variable crustal thickness, and moderate seismic hazard, supporting the development of the 2021 seismic hazard model of Slovenia. We estimated the lower seismogenic depth using seismological and geological data and compared them. The seismological estimate was based on two regional earthquake catalogues prepared for this study. In the area source model, estimates of lower seismogenic depth from seismological data are deeper or equal to the ones derived from geological data, except in one case. In the fault source model, we analyzed each fault individually and chose seismological lower depth estimates in 12 among 89 faults as more representative. The seismogenic thickness for each individual fault source was determined for seismic coupling determination. The seismic coupling was assessed by two approaches, i.e. we chose the most trusted value from the literature, and the value determined for each fault individually by using the approach based on the updated regional fault and earthquake datasets. The final estimate of seismic coupling ranges from 0.77 to 0.38. We compared the tectonic moment rate based on long-term slip rate using different values of seismic coupling with the seismic moment rate obtained from the earthquake catalogue. The analysis is done for the whole area, as well as for the individual area zones. The analysis of N-S components of estimated slip for the largest faults in the area of west Slovenia shows that the regional geologic and geodetic shortening rates are comparable. The total activity rate of three global seismic source models is compared, which gives up to a 10 % difference. Our results contribute to a better understanding of the seismic activity in the region and the approach for seismic coupling estimation can be applied in other similar regions. [ABSTRACT FROM AUTHOR]

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This study provides a comprehensive probabilistic seismic hazard assessment for Karaj, the capital of Alborz province. In the present study, two probabilistic approaches, including the classical and Monte Carlo methods are applied. In this regard, the most recent earthquake catalog of the region, as well as, the most appropriate GMPEs based on the statistical tests of the likelihood and the log-likelihood are used. The results indicated that there are differences between the results of two approaches, which is intensified in the longer return periods. This disparity mainly stemmed from the different concept of two methods for incorporating the aleatory uncertainty. In the classical PSHA, the aleatory uncertainty takes into account using the integration, which is truncated at a fixed number of the logarithmic standard deviation. While, in the Monte Carlo simulation approach, the aleatory uncertainty is considered in calculation using random sampling of GMPEs variability. In addition, the ground motion shaking map of the region for the dominant seismic scenarios, including the rupture of the North-Tehran and Eshtehard faults are developed. These seismic scenarios have the potential of producing the greatest acceleration; consequently, the most vulnerability. The outcomes of this study can be used for providing urban plan or estimating the probable economic and casualty losses of Karaj. [ABSTRACT FROM AUTHOR]

Many widely used models amount to an elaborate means of making up numbers—but once a number has been produced, it tends to be taken seriously and its source (the model) is rarely examined carefully. Many widely used models have little connection to the real-world phenomena they purport to explain. Common steps in modeling to support policy decisions, such as putting disparate things on the same scale, may conflict with reality. Not all costs and benefits can be put on the same scale, not all uncertainties can be expressed as probabilities, and not all model parameters measure what they purport to measure. These ideas are illustrated with examples from seismology, wind-turbine bird deaths, soccer penalty cards, gender bias in academia, and climate policy. [ABSTRACT FROM AUTHOR]

The tectonically active southwestern part of Turkey is dominated by the Aegean Extensional Province. The primary aim of this study is to evaluate the seismic hazard for the cities in SW Turkey using a probabilistic approach. As part of this research, a new earthquake database based on a unified moment magnitude scale was created, which contains shallow crustal earthquakes from 1000 to 2021. The catalog's foreshock and aftershock occurrences were excluded depending on the space–time windows, and a catalog completeness analysis was conducted. The uncertainty in magnitude determination was taken into account. The seismic sources were defined as homogeneous area source zones, taking into consideration the active fault zones. The activity rate and the Gutenberg–Richter b parameter as earthquake hazard parameters for each seismic source have been evaluated by the Kijko–Smit maximum likelihood estimation method. An "efficacy test," which uses the average log likelihood value (LLH), was performed to find the suitable ground motion prediction equations for SW Turkey. The maximum magnitude (Mmax) of each seismic source was calculated based on the regional rupture characteristics and the Kijko–Sellevoll methods. Seismic hazard maps for SW Turkey were developed for Peak ground acceleration (PGA), spectral acceleration with periods of 0.2 and 1 s and for bedrock with a hazard level of 10% probability of exceedance in 50 years by using Geographical Information System software. Based on this study, the PGA values on the bedrock in SW Turkey range from 0.253 to 0.572 g. As part of this research, seismic hazard curves and uniform hazard spectrums were created for the settlement areas of the cities in SW Turkey. In addition to this PSHA, PGA values at the settlement areas with events at probable future rupture locations were estimated for different site amplification classes. [ABSTRACT FROM AUTHOR]

Here, we describe a technique for probabilistic seismic hazard assessment based on a combination of a characteristic earthquake model and an areal seismic source model. One of the active regions in the Middle East, the Gulf of Aqaba, was used as an example. Five active faults located inside the Gulf of Aqaba (GA), representing the southern part of the Dead Sea Transform fault system, were included in the characteristic earthquake model. The hazard estimations were obtained using the Monte Carlo approach, consisting of the generation of a set of synthetic earthquake catalogs and the calculation of ground motion from all earthquakes in all catalogs. It is assumed that the large earthquakes with magnitudes M > 6.5 may happen on the GA active fault system, while earthquakes with magnitudes M ≤ 6.5 are distributed inside the areal GA zone. This technique considers individual as well as combined faults. The stochastic catalogs generated using the characteristic earthquake model showed conformity with the recurrence of large (M > 6.5) historical earthquakes that have occurred in the studied region over the last 1000 years. The seismic hazard maps obtained using the characteristic earthquake model clearly reflected the location and influence of the considered faults. It seems that the areal source model, in which a single zone is used for the entire Gulf of Aqaba, does not adequately describe seismic hazard. For practical applications, we suggest calculating the hazard from separate faults and their combinations and then constructing the final seismic hazard map using a weighted average scheme. • Gulf of Aqaba is a region with high seismic activity in the Middle East. • Seismic hazard assessment was performed for areal seismic sources and active faults. •Monte-Carlo generation of stochastic long-duration seismic catalogs is used. • The characteristic earthquake model is accepted for active faults. • Stochastic catalogs show conformity with recurrence of large historical earthquakes. [ABSTRACT FROM AUTHOR]

Slovenia is an earthquake-prone country with a moderate seismic hazard, characterized by relatively long recurrence intervals for strong earthquakes. With newly compiled data and revised info on active faults of the region, we are now able to supplement and enhance the probabilistic seismic hazard assessment, which was previously based mainly on the seismic catalog. The core of the seismic hazard model is the seismogenic source model combining various seismogenic representations i.e. area and gridded sources, and active faults. The ground motion model is characterized by a backbone model with regionalized parameters, which was also used to update the European seismic hazard model. We considered epistemic uncertainty in the most influential input parameters, implemented in a logic tree with 1377 branches. Considering the existing and forthcoming requests of the seismic design standard—Eurocode 8, we have developed the peak ground acceleration map of Slovenia and spectral acceleration maps for ten spectral periods, as well as seismic hazard curves and spectra for selected locations. The highest peak ground acceleration values (0.325 g) are at the western border of Slovenia with Italy. Other high-hazard areas extend across the Dinarides, in southeast Slovenia, and around the capital Ljubljana. [ABSTRACT FROM AUTHOR]

The size and importance of maritime transportation in world trade are well known. The number of ports, which is one of the most important elements of maritime transportation, is increasing day by day not only in our country but also throughout the world. Many active fault systems in our country are located at sea. In the Marmara Region in particular, most active branches of the North Anatolian Fault system pass through the Sea of Marmara. When offshore structures such as ports are constructed in high-seismicity zones such as the Sea of Marmara, conducting site-specific seismic hazard studies is necessary to reduce the seismic risk of offshore structures. In 2007, the first Turkish Seismic Design Code for Port Structures was published, which introduced new design concepts in the seismic design of offshore structures. According to this code, the design can be finalized in three basic steps: assessment of regional seismicity, estimation of geotechnical hazards, and soil-structure interaction analysis of offshore structures. Nowadays, the first Turkish Seismic Design Code for Port Structures is on the verge of a major update, which was published as a draft report in May 2019. In this manuscript, site-specific probabilistic seismic hazard analysis is needed to determine the seismic hazard associated with typical port sites. Considering this new draft code as a guideline document, we developed consistent seismic hazard studies for offshore structures within the Haydarpaşa Port sites. Unlike the old one, this new document identifies four different levels of ground motion: minimum damage level earthquake (TR=72), limited damage level earthquake (TR=144), controlling damage level earthquake (TR=475), and maximum considered earthquake (TR=2.475).

The probabilistic seismic hazard analysis is conducted for the seismically active National Capital Region (NCR) of India, one of the most densely populated regions in the world, to quantify the peak ground acceleration (P GA) at bedrock level by considering seismogenic source characteristics, smoothened grid seismic zoning, magnitude recurrence model, uncertainties, and suites of suitable ground motion prediction equations. The spatial distribution of the resulting P GA value is presented using GIS for the entire NCR of India for 10% and 2% probability of exceedance in 50 years and 100 years. The estimated P GA values are found to vary in the range of 0.12 to 0.37 g and 0.15 to 0.40 g for a 2% probability of exceedance in 50 years and 100 years, respectively. And the P GA values range from 0.07 to 0.33 g and 0.08 to 0.35 g for the 10% probability of the exceedance in 50 years and 100 years, respectively. The results reveal that the eastern region of the study area falls under high seismicity due to its proximity to the Himalayan zone, a highly seismically active region. High P GA values are also observed for south-eastern regions of the NCR of India due to the vicinity of the Great-Boundary fault, Mathura fault, Moradabad fault.

Since Metropolitan Manila is known to be susceptible to seismic hazards, it is necessary to consider multiple factors in assessing this hazard. Aside from ground motion, the properties of soil which lead to the amplification of seismic waves should be considered. This study aimed to develop a seismic hazard map for Metro Manila considering the soil properties in the area by using Midorikawa & Hori site amplification model. Probabilistic seismic hazard assessment was conducted using earthquake data within 250 km of Metropolitan Manila for 10% and 2% probabilities of exceedance. The site amplification factors were computed using calculated shear wave velocities from SPT-N values. The calculated ground motions were amplified using the site amplification factors considering short-period and mid-period amplifications. The constructed maps of amplified peak ground acceleration (PGA) values showed how soil properties affect the ground motion. It was found that for a short-period amplification, the average PGAs is 0.538 g, and 0.659 g for 10%, and 2% probabilities of exceedance, respectively. While for mid-period amplification, the average PGAs is 0.589 g, and 0.830 g for 10%, and 2% probabilities of exceedance. Using the amplified seismic hazard maps, a better approximation of seismic hazards can be generated for future use. [ABSTRACT FROM AUTHOR]

Earthquakes are one of the natural disasters that pose a major threat to human lives and property. Earthquake prediction propels the construction and development of modern seismology; however, current deterministic earthquake prediction is limited by numerous difficulties. Identifying the temporal and spatial statistical characteristics of earthquake occurrences and constructing earthquake risk statistical prediction models have become significant; particularly for evaluating earthquake risks and addressing seismic planning requirements such as the design of cities and lifeline projects based on the obtained insight. Since the 21st century, the occurrence of a series of strong earthquakes represented by the Wenchuan M8 earthquake in 2008 in certain low-risk prediction areas has caused seismologists to reflect on traditional seismic hazard assessment globally. This article briefly reviews the development of statistical seismology, emphatically analyzes the research results and existing problems of statistical seismology in seismic hazard assessment, and discusses the direction of its development. The analysis shows that the seismic hazard assessment based on modern earthquake catalogues in most regions should be effective. Particularly, the application of seismic hazard assessment based on ETAS (epidemic type aftershock sequence) should be the easiest and most effective method for the compilation of seismic hazard maps in large urban agglomeration areas and low seismic hazard areas with thick sedimentary zones. [ABSTRACT FROM AUTHOR]

The backbone modeling in ground-motion characterization (GMC) is a useful methodology to describe the epistemic uncertainty in median ground-motion predictions. The approach uses a backbone ground-motion model (GMM) and populates the GMC logic tree with the scaled and/or adjusted versions of the backbone GMM to capture the epistemic uncertainty in median ground motions. The scaling and/or adjustment should represent the specific features and uncertainties involved in source, path, and site effects at the target site. The identification of the backbone model requires different considerations specific to the nature of the ground-motion hazard problem. In this article, we present a scaled backbone modeling approach that considers the magnitude- and distance-scaling predictors as well as their correlation to address the epistemic uncertainty in median ground-motion predictions. This approach results in a trivariate normal distribution to fully define a range of epistemic uncertainty in a model sample space. The simultaneous consideration of magnitude and distance scaling while defining the epistemic uncertainty and the methodology followed for the simplified representation of trivariate normal distribution in ground-motion logic tree are the two important features in our procedure. We first present the proposed approach that is followed by a case study for Central and Eastern North America (CENA) stable continental region. The case study discusses the underlying assumptions and limitations of the proposed approach. [ABSTRACT FROM AUTHOR]

Featured Application: Methodology has been developed and applied with the aim to contribute to the justification of safety of the Paks nuclear site in Hungary. Permanent ground displacements/deformations caused by earthquakes can seriously challenge the safety of the nuclear power plants. The state-of-the-art hazard analysis methods provide a fault displacement hazard curve, i.e., the annual probability of given measure of displacement will be exceeded. The evaluation of ground displacement hazard requires great effort, empirical evidence, and sufficient data for the characterization of the fault activity and capability to cause permanent surface displacement. There are practical cases when the fault at the site area revealed to be active, and, despite this, there are no sufficient data for the evaluation of permanent ground displacements hazard and for judging on the safety significance of permanent ground displacement. For these cases, a methodology is proposed that is based on the seismotectonic modelling and results of the probabilistic seismic hazard analysis. The method provides conservative assessment of the annual probability of fault displacement that allows the decision whether permanent displacement hazard is relevant to nuclear power plant safety. The feasibility and applicability of the method is demonstrated for the Paks site, Hungary. [ABSTRACT FROM AUTHOR]

Although probabilistic seismic hazard assessment (PSHA) has been carried out in a few countries in West Africa (WA), large-scale PSHA is still lacking in the region. Dearth of earthquake data, sparse or complete absence of a network of seismographic stations, lack of skilled geoscientists, absence of appropriate policies to encourage PSHA, and so on are responsible for the situation. This research therefore is aimed at computing the area-characteristic seismic hazard parameters (b-value, activity rate (λ_4.0), and the regional maximum earthquake magnitude (Mmax)) for Ghana, Nigeria, Benin, Togo, Burkina Faso, and Cote D'Ivoire to assist in future PSHA studies and planning. The earthquake catalogue which covers the 1615–2020 period with magnitudes ranging from 1.5 to 6.8 was compiled from regional stations, publications, and the International Seismological Commission (ISC). The initial catalogue with 259 events was reduced to 98 events after declustering (removal of dependent events) and harmonization of magnitudes into moment magnitude (MW); six subcatalogues were then created from the main one, each representing the respective country. The method of maximum likelihood estimate was adopted in the computation of the parameters. Firstly, the hazard parameters for the whole area were computed using the ZMAP. Secondly, the Ha3 program was utilized to compute the parameters for the subcatalogues. The results of the seismicity parameters for the whole region are b = 0.98, λ_4.0 = 0.631, Mmax=7.21. The results for the parameters for each contributing country are Ghana (b = 0.76, λ_4.0 = 0.081, Mmax = 7.03); Nigeria (b = 0.68, λ_4.0 = 0.026, Mmax = 6.22); Togo (b = 0.96, λ_4.0 = 0.020, Mmax = 5.01); Benin Republic (b = 0.92, λ_40 = 0.024, Mmax = 5.19); Cote D'Ivoire (b = 0.94, λ_4.0 = 0.033, Mmax = 5.28); and Burkina Faso (b = 0.91, λ_4.0 = 0.031, Mmax = 5.10). The return periods and probabilities of exceedance of magnitudes 4.0 to 7.0 for each zone in 1, 50, 100, and 500 years are also presented in this study. The 0.98 b-value for the whole region relates well with the expected b-value characteristic for stable cratonic areas. Besides, the low or high values of the b-values have indicated either a fault-slip-related seismicity (Ghana and Nigeria) or of stress change seismicity (Benin, Burkina Faso, Cote D'Ivoire, and Togo) regions. [ABSTRACT FROM AUTHOR]

A probabilistic seismic hazard assessment has been carried out along the continental section of the Cameroon volcanic line (CVL) in West Africa. We compiled a catalogue of local earthquakes from different sources and homogenize the magnitudes to moment magnitude (Mw). The seismicity of the CVL is concentrated around Mount Cameroon the active volcano and diffuse on the rest. Three seismic source zones were identified: one in Mount Cameroun, the second NE of the volcano in the grabens of Kumba-Tombel, and the third seismic source corresponds to West Cameroon horst. The recurrence model is that of Gutenberg and Richter, ZMAP software was used to decluster the catalogue and to determine seismic parameters for each source zone. To calculate the hazard, we choose two ground motion prediction equations, and to account for uncertainties, a logic tree approach was implemented using CRISIS software. We estimated the peak ground acceleration (PGA) for eleven cities spread along the CVL, for return period (RP) 475 and 2475 years. The results show that for RP 475 years, Buea, located at the foot of Mount Cameroon, has a PGA of 10% g. This value decreases as one moves away from Buea. The seismic hazard was also calculated for the period of 0.2s. Uniform hazard spectra for RP 475 and 2475 years are plotted for three cities, each chosen in one of the seismic source zone. For each city and RP, the spectral acceleration increases with the period, up to around 0.1s, and then it decreases as the period increases. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard analysis (PSHA), as a tool to assess the probability that ground motion of a given intensity or larger is experienced at a given site and time span, has historically comprised the basis of both building design codes in earthquake-prone regions and seismic risk models. The PSHA traditionally refers solely to mainshock events and typically employs a homogeneous Poisson process to model their occurrence. Nevertheless, recent disasters, such as the 2010–2011 Christchurch sequence or the 2016 Central Italy earthquakes, to name a few, have highlighted the potential pitfalls of neglecting the occurrence of foreshocks, aftershocks, and other triggered events, and pinpointed the need to revisit the current practice. Herein, we employ the epidemic-type aftershock sequence (ETAS) model to describe seismicity in Central Italy, investigate the model's capability to reproduce salient features of observed seismicity, and compare ETAS-derived one-year hazard estimates with ones obtained with a standard mainshock-only Poisson-based hazard model. A companion paper uses the hazard models derived herein to compare and contrast loss estimates for the residential exposure of Umbria in Central Italy. [ABSTRACT FROM AUTHOR]

The size and importance of maritime transportation in world trade are well known. The number of ports, which is one of the most important elements of maritime transportation, is increasing day by day not only in our country but also throughout the world. Many active fault systems in our country are located at sea. In the Marmara Region in particular, most active branches of the North Anatolian Fault system pass through the Sea of Marmara. When offshore structures such as ports are constructed in high-seismicity zones such as the Sea of Marmara, conducting site-specific seismic hazard studies is necessary to reduce the seismic risk of offshore structures. In 2007, the first Turkish Seismic Design Code for Port Structures was published, which introduced new design concepts in the seismic design of offshore structures. According to this code, the design can be finalized in three basic steps: assessment of regional seismicity, estimation of geotechnical hazards, and soil-structure interaction analysis of offshore structures. Nowadays, the first Turkish Seismic Design Code for Port Structures is on the verge of a major update, which was published as a draft report in May 2019. In this manuscript, site-specific probabilistic seismic hazard analysis is needed to determine the seismic hazard associated with typical port sites. Considering this new draft code as a guideline document, we developed consistent seismic hazard studies for offshore structures within the Haydarpaşa Port sites. Unlike the old one, this new document identifies four different levels of ground motion: minimum damage level earthquake (TR=72), limited damage level earthquake (TR=144), controlling damage level earthquake (TR=475), and maximum considered earthquake (TR=2.475). [ABSTRACT FROM AUTHOR]

The Monte-Carlo (MC) simulation approach has been widely applied to the problem of probabilistic seismic hazard assessment (PSHA) for geographically distributed systems. Although the conventional integral approach is well-established in PSHA, the MC simulation approach is an efficient and flexible alternative when complicated factors, such as spatial correlation of ground shaking are involved. The objective of this study is to assess how the ergodic assumption influences the economic loss results for a region. To meet this objective, MC simulation and multi-scale random fields techniques are used to assess the probabilistic seismic hazard of a region, while incorporating estimated site-terms (δS2Ss) based on available strong-motion records at specific sites and spatially correlated δS2Ss at others in addition to single-station sigma to the PSHA process. The proposed method is applied to the Fatih district of Istanbul in the case of a moment magnitude 7.3 earthquake on the Marmara Fault. Results indicate that the probability for total economic loss being underestimated due to the ergodic assumption by at least 29% is 0.50 in the case of a moment magnitude 7.3 earthquake on the Marmara Fault. [ABSTRACT FROM AUTHOR]

A set of 3D physics‐based numerical simulations (PBS) of possible earthquakes scenarios in Istanbul along the North Anatolian Fault (Turkey) is considered in this article to provide a comprehensive example of application of PBS to probabilistic seismic hazard (PSHA) and loss assessment in a large urban area. To cope with the high‐frequency (HF) limitations of PBS, numerical results are first postprocessed by a recently introduced technique based on Artificial Neural Networks (ANN), providing broadband waveforms with a proper correlation of HF and low‐frequency (LF) portions of ground motion as well as a proper spatial correlation of peak values also at HF, that is a key feature for the seismic risk application at urban scale. Second, before application to PSHA, a statistical analysis of residuals is carried out to ensure that simulated results provide a set of realizations with a realistic within‐ and between‐event variability of ground motion. PBS results are then applied in a PSHA framework, adopting both the "generalized attenuation function" (GAF) approach, and a novel "footprint" (FP)‐based approach aiming at a convenient and direct application of PBS into PSHA. PSHA results from both approaches are then compared with those obtained from a more standard application of PSHA with empirical ground motion models. Finally, the probabilistic loss assessment of an extended simplified portfolio of buildings is investigated, comparing the results obtained adopting the different approaches: (i) GMPE, (ii) GAF, and (iii) FP. Only FP turned out to have the capability to account for the specific features of source and propagation path, while preserving the proper physically based spatial correlation characteristics, as required for a reliable loss estimate on a building portfolio spatially distributed over a large urban area. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive open probabilistic seismic risk model for India. The proposed model comprises a nationwide residential and non-residential building exposure model, a selection of analytical seismic vulnerability functions tailored for Indian building classes, and the open implementation of an existing probabilistic seismic hazard model for India. The vulnerability of the building exposure is combined with the seismic hazard using the stochastic (Monte Carlo) event-based calculator of the OpenQuake engine to estimate probabilistic seismic risk metrics such as average annual economic losses and the exceedance probability curves at the national, state, district, and subdistrict levels. The risk model and the underlying datasets, along with the risk metrics calculated at different scales, are intended to be used as tools to quantitatively assess the earthquake risk across India and also compare with other countries to develop risk-informed building design guidelines, for more careful land-use planning, to optimize earthquake insurance pricing, and to enhance general earthquake risk awareness and preparedness. [ABSTRACT FROM AUTHOR]

The Taiwan Earthquake Model (TEM) published the first version of the Taiwan probabilistic seismic hazard assessment (named TEM PSHA2015) 5 years ago. For updating to the TEM PSHA2020, we considered an updated seismogenic structure database, including the structures newly identified with 3D geometry, an earthquake catalog made current to 2016, state-of-the-art seismic models, a new set of ground motion prediction equations, and site amplification factors. In addition to earthquakes taking place on each individual seismogenic structure, the updated seismic model included the possibility of an earthquake occurring on multiple structures. To include fault memory for illustrating activity on seismogenic structure sources, we incorporated the Brownian passage time model. For the crustal seismicity that cannot be attributed to any specific structure, we implemented both area source and smoothing kernel models. A new set of ground motion prediction equations is incorporated. In addition to the calculation of hazard at engineering bedrock, our assessment included site amplification factors that competent authorities of governments and private companies could use to implement hazard prevention and reduction strategies. [ABSTRACT FROM AUTHOR]

A probabilistic seismic hazard assessment is applied, for the first time in the case of Sakhalin Island, using a regional ground motion prediction equation in terms of the peak ground acceleration. The seismic hazard maps for 475-year-long and 975-year-long recurrence intervals are made for southern Sakhalin Island. [ABSTRACT FROM AUTHOR]

The selection of ground motion models, and the representation of their epistemic uncertainty in the form of a logic tree, is one of the fundamental components of probabilistic seismic hazard and risk analysis. A new ground motion model (GMM) logic tree has been developed for the 2020 European seismic hazard model, which develops upon recently compiled ground motion data sets in Europe. In contrast to previous European seismic hazard models, the new ground model logic tree is built around the scaled backbone concept. Epistemic uncertainties are represented as calibrations to a reference model and aim to characterise the potential distributions of median ground motions resulting from variability in source scaling and attenuation. These scaled backbone logic trees are developed and presented for shallow crustal seismic sources in Europe. Using the new European strong motion flatfile, and capitalising on recent perspectives in ground motion modelling in the scientific literature, a general and transferable procedure is presented for the construction of a backbone model and the regionalisation of epistemic uncertainty. This innovative approach forms a general framework for revising and updating the GMM logic tree at national and European scale as new strong motion data emerge in the future. [ABSTRACT FROM AUTHOR]

A seismic hazard map for the national seismic design code of Pakistan (i.e., Building Code of Pakistan) is derived using probabilistic seismic hazard assessment (PSHA) approach. In order to update the seismic code, an updated seismic zoning map is required that should be based on usage of the recent seismic hazard elements. PSHA of Pakistan is an essential and important milestone. For this purpose, the standard Cornell–McGuire (1968–1976) approach is employed, and the computations are made over a rectangular grid of 0.1°. The main features of this study include usage of a recently compiled earthquake catalogue, recent ground motion prediction equations and an updated seismic source model. The resulting ground motions are obtained as peak ground acceleration (PGA) and 5% damped spectral acceleration (SA) at T = 0.2 s and T = 1.0 s for 475-, 975- and 2475-year return periods (RPs) (evaluated for the flat rock site conditions). Results of the study show that seismic hazard in Pakistan is highest in its central and northern parts. In the central part near Quetta, severe seismic hazard (PGA 0.40 g) is observed. Among the important cities in Pakistan, Balakot city is likely to experience a PGA value of 0.36 g, while Islamabad, Peshawar and Chitral are likely to experience 0.33 g. The cities of Gilgit, Karachi and Gwadar experience ground motion values of 0.34, 0.26 and 0.29 g, respectively, for the 475-year return period (RP). It has also been observed that ground motion values show variation in the distribution and magnitude in contrast to the hazard map of national design code. The hazard map presented in this study is the improved seismic hazard zoning map of Pakistan that would be helpful in developing pre-disaster mitigation strategies and risk assessment studies in Pakistan. It is concluded that the seismic zoning map of the national seismic design code of Pakistan underestimates the ground motion values, and it should be updated or replaced. [ABSTRACT FROM AUTHOR]

This study aims to build on the existing knowledge and improve the overall PSHA results by modifying source, path and site characteristics for Bangladesh. Firstly, six potential seismotectonic zones have been re-defined based on the recent study of Wang et al. (J Geophys Res Solid Earth 119:3576–3822, 2014) and Nath and Thingbaijam (J Seismol 15(2):295–315, 2011), and the updated earthquake catalogue has been declustered using two methods. Important source parameters, such as recurrence b-values and maximum magnitudes, have been determined using the Maximum Likelihood and cumulative moment methods, respectively, and their uncertainties have been addressed using a logic-tree approach. Secondly, based on literature review and studies in neighboring countries, suitable GMPEs have been selected for the seismic zones and the uncertainties have been addressed using a logic tree approach. A significant novelty of the study lies in the consideration of the site effects by integrating Vs30 values throughout the country. The ground motions—PGA and SA (at 0.2, 1.0 and 2.0 s) are computed using GEM's OpenQuake and presented in form of hazard maps for 2% and 10% probabilities of exceedance in 50 years as well as mean hazard curves and uniform hazard spectra. Disaggregation for capital city Dhaka has also been carried out to show the hazard contributions of magnitude–distance pairs. The spatial distribution of PGA and SA are found remarkably higher than previous findings, likely due to differences in parameters and uncertainties. The results show a marked increase (by almost 20%) in the observed ground motions with respect to those carried out previously by uniformly characterizing the whole country as a firm rock. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard assessments (PSHA) form the basis for calculating seismic loads in most contemporary seismic provisions in building codes around the world. The current building code of Iraq, which was published in 1997, is currently undergoing a significant engineering update. This study was undertaken in order to support the building code update and to satisfy the need in Iraq for a contemporary assessment of seismic hazard in terms of spectral accelerations. Seismic source characterization largely relies on a newly compiled earthquake catalog since sufficiently detailed information is not available on active faulting in the country even though there are numerous known active faults. There is also a lack of locally recorded strong-motion data. As a result, we make use of attenuation tomography studies in the region to compare local attenuation characteristics with that in other parts of the world where ground-motion prediction equations are available for use in PSHA. For most of the country, the attenuation of 1HzLg waves indicates an attenuation rate that is slower than active tectonic regions but faster than stable continental regions. Hence, we use ground-motion prediction equations from active tectonic and stable continental regions, weighted equally. The PSHA results are presented for a 2% chance of being exceeded in 50 years and on a reference ground condition of the National Earthquake Hazards Reduction Program (NEHRP) site class B. The probability level and reference ground conditions were selected to be consistent with the update of Iraq's building code. The largest hazard, and consequently the design ground motions, is in the northern cities of Sulaymaniyah and Erbil, consistent with the fact that they are the two urban areas closest to major tectonic features to the north and east of Iraq. Additionally, the Badra–Amarah fault zone is a significant contributor to seismic hazard in the country; therefore, urban areas near it exhibit high seismic hazard. [ABSTRACT FROM AUTHOR]

The Northeast of Thailand is defined as a low seismic hazard region. However, earthquakes were reported and felt by local people around 25 years ago. Using probabilistic seismic hazard analysis (PSHA), this research evaluates the seismic hazard in the Northeast region of Thailand to be the database for seismic design. The seismic hazard is expressed in the term of peak ground acceleration (PGA) at base rock level. The crustal faults and earthquake events are considered as the seismic source in this evaluation. Two crustal faults are evaluated in Thakhaek fault and Phetchabun fault, which have not been considered before in PSHA. Earthquake events are classified into two types: background seismicity zones and subduction zones. The results reveal that the highest peak ground acceleration at base rock level is in Bueng Kan province and Nakhon Phanom province. The evaluated seismic hazard in the Northeast region is approximately 30% g and 12% g with a return period of 2,475 years and 475 years, respectively. Results obtained from this study are about two times higher than the Earthquake Resistant Design code 1302 of Thailand. The evaluated seismic hazard is higher than the peak ground accelerations that can cause damage to building structures (>3.9% g). [ABSTRACT FROM AUTHOR]

This paper deals with the seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel in the Czech Republic. The basic source of data for historical earthquakes up to 1990 was the seismic website [10]. The most intense earthquake described occurred on September 15, 1590 in the Niederroesterreich region (Austria) in the historical period; its reported intensity is Io = 8-9. The source of the contemporary seismic data for the period since 1991 to the end of 2014 was the website [11]. It may be stated based on the databases and literature review that in the period from 1900, no earthquake exceeding magnitude 5.1 originated in the territory of the Czech Republic.

The article talks about the systematics and parametrization of the significance of geofluids hosted in the deep crust. Topics covered include the significance of studies about the occurrence of geofluids in faulted areas, how geofluids may contribute to define a more effective description of the studied area like Probabilistic Seismic Hazard Assessment (PSHA) and Deterministic Seismic Hazard Assessment (DSHA), and concentration and pressure gradients that geofluids are subjected to.

Permanent ground displacements/deformations caused by earthquakes can seriously challenge the safety of the nuclear power plants. The state-of-the-art hazard analysis methods provide a fault displacement hazard curve, i.e., the annual probability of given measure of displacement will be exceeded. The evaluation of ground displacement hazard requires great effort, empirical evidence, and sufficient data for the characterization of the fault activity and capability to cause permanent surface displacement. There are practical cases when the fault at the site area revealed to be active, and, despite this, there are no sufficient data for the evaluation of permanent ground displacements hazard and for judging on the safety significance of permanent ground displacement. For these cases, a methodology is proposed that is based on the seismotectonic modelling and results of the probabilistic seismic hazard analysis. The method provides conservative assessment of the annual probability of fault displacement that allows the decision whether permanent displacement hazard is relevant to nuclear power plant safety. The feasibility and applicability of the method is demonstrated for the Paks site, Hungary.

Nomograms are an easy to use and visually attractive graphical tool to solve for any of the variables within an often complex equation. In seismology, the most well-known nomogram is a three-parallel-scale graphic for the calculation of local magnitude given the epicentral distance and trace amplitude. Until the advent of computers, nomograms were often employed by engineers and scientists in many fields as they provide a means for rapid and accurate calculations as well as helping the user understand the sensitivity of the final results to the input parameters. It is this aid to understanding that remains a key attraction of these graphical tools, which are now rarely seen (although they remain common in some fields of medicine where they are used for rapid screening and estimating risks). In this research letter, we present a nomogram summarising the results of simple probabilistic seismic hazard assessments (PSHAs) for peak ground acceleration and elastic response spectral acceleration for a structural period of 1s and return periods from 100 to 2500 years, where the effects of the activity rate and the slope of the Gutenberg-Richter relation are captured. We believe that this nomogram has considerable educational benefit for engineering seismology students, decision makers and other non-expert users of results of PSHAs. [ABSTRACT FROM AUTHOR]

A new probabilistic seismic hazard assessment has been performed for the Democratic Republic of Congo (DRC) and surrounding areas. The DRC encompasses both intra-plate and active tectonic areas associated with the Congo Craton and the western branch of the East African Rift System, respectively. The seismic hazard assessment is based on the new Sub-Saharan-Global Earthquake Model Sub-Saharan–Global Earthquake Model earthquake catalogue with homogeneous magnitude representation (Mw) created by augmenting available global catalogues (e.g. International Seismological Center (ISC)-Reviewed, ISC–GEM, GCMT) with information from local agencies and regional projects, particularly from the AfricaArray network. This catalogue spans from 1900 to 2015. The initial declustered catalogue has 782 events. The historical earthquake record is sparse with significant variation in completeness over time across different regions. After taking the completeness of the catalogue into account, the final declustered catalogue used to calibrate the magnitude-frequency distribution of events used for the seismic hazard assessment spans 55 years (from 1960 to 2015) with 398 events and a magnitude of completeness of about 4.5. The maximum credible magnitude of earthquakes was determined using the entire catalogue from 1900 to 2015. The seismotectonic zonation into 15 seismic source areas was done on the basis of the regional geological structure, neotectonic fault systems, basin architecture and distribution of thermal springs and earthquake epicentres. Also, consideration was given to a regional strain rate model developed for the East African Rift by Saria et al. (Journal of Geophysical Research, 119, 3584–3600, 2014) in the frame of the GEM Strain Rate Project. Tectonic information was derived mostly from the scientific literature and by integration of available datasets. The current area source model consists of a total of 15 seismic zones distributed over 6 main tectonic groups that we assume to have comparable rheological and mechanical behavior with respect to the underlying crustal geology. The definition of these groups is essential for the regional calibration of b values. The b value is expected to be regionally stable with variations less than the uncertainty limits, while the activity rate λ is liable to vary substantially from one seismic source zone to another. The Gutenberg–Richter seismic hazard parameters were determined using Aki's maximum likelihood method Aki (Bulletin of the Earthquake Research Institute, Tokyo University, 43, 237–239, 1965) and Weichert's method Weichert (Bulletin of the Seismological Society of America, 70, 1337–1346, 1980), and compared with extension of the Aki-Utsu b value estimator for incomplete catalogues Kijko and Smit (Bulletin of the Seismological Society of America, 102, 1183–1287, 2012). Hazard computations were performed using the OpenQuake engine (version 2.7.0-1). The peak ground acceleration (PGA) and spectral acceleration at periods of 0.05, 0.1, 0.2, 0.5, 1 and 2 s was calculated using four ground motion prediction equations (GMPEs): two for active shallow crust Chiou et al. (Earthquake Spectra, 30, 1117–1153, 2014); Akkar et al. (Bulletin of Earthquake Engineering, 12, 359–387, 2014) and two for stable continental conditions Atkinson et al. (Bulletin of the Seismological Society of America, 96, 2181–2205, 2006; Pezeshk et al. (Bulletin of the Seismological Society of America, 101, 1859–1870, 2011) for soil sites corresponding to Vs 30 = 600, 760 and 1500 m/s at 11 cities of the DRC and surrounding areas. The results are consistent with those obtained using the regional frequency-independent attenuation law of Mavonga (Physics of the Earth and Planetary Interiors, 62, 13–21, 2007b) developed in the Kivu Rift segment and others Twesigomwe (Journal of African Earth Sciences, 24, 183–195, 1997), and Jonathan (Some aspects of seismicity in Zimbabwe and Eastern and Southern Africa. M.Sc. thesis. Institute of solid earth physics, Univ. Bergen, Bergen, Norway, pp. 100 (1996)), using Crisis 2012 software. [ABSTRACT FROM AUTHOR]

Prague is the capital of the Czech Republic with 1.3 million inhabitants. It is situated in an intraplate region with low seismicity. The seismic hazard is low, but not negligible. In its evaluation, we face the following challenging issues: (1) there have been no M > 6 events during the period covered by historical catalog (Giardini et al. 2013) although there is evidence from paleoseismic research of earthquakes with magnitude of at least 6.5. It is difficult to determine a reliable magnitude frequency distribution from sparse data. (2) There are no GMPEs determined from strong ground motion data for the region of interest. Therefore, we studied the attenuation from recent weak earthquakes in order to determine which of the published GMPEs are suitable for the region. (3) There are plenty of faults in the city and its neighborhood, all of them believed to be seismically inactive. We have to quantify the probability of an unexpected earthquake on such faults. We used the concept of diffused seismicity for this purpose. (4) The hazard is dominated by the 140 km distant West Bohemia Source Zone with earthquake swarm activity, which does not follow the classical mainshock-aftershock model. The results in the present study were obtained through the OpenQuake engine, the open-source software for seismic risk and hazard assessment developed within the global earthquake model (GEM) initiative. The seismic hazard for Prague (expressed in terms of peak ground acceleration) is below 0.1 g for the returning period of 10,000 years. [ABSTRACT FROM AUTHOR]

Since the basic work of Cornell, many studies have been conducted in order to evaluate the probabilistic seismic hazard (PSHA) at a given site or at a regional scale. In general, results of such studies are used as inputs for regulatory hazard maps or for risk assessments. Such approaches are nowadays considered as well established and come more and more used worldwide, in addition to deterministic approaches. Nevertheless, some discrepancies have been observed recently in some PSHA, especially from studies conducted in areas with low to moderate seismicity. The lessons learnt from these results lead to conclude that, due to epistemic uncertainties inherent to such a domain, some deterministic choices have to be made and, depending on expert judgments, may lead to strong differences in terms of seismic motion evaluation. In this context, the objective of this paper is to present a methodology that can be used to take into consideration instrumental and historical observations in order to reduce epistemic uncertainties in a PSHA. The method developed here is based on a Bayesian inference technique used in order to quantify the likelihood of the prior estimation, and finally update the PSHA. The period of observation under consideration is the completeness period for each set of observation used. The updating process is developed at a regional scale, over a significant number of stations. The potential correlation between points of observation is also discussed and accounted for. Finally, a case of application is proposed on the French metropolitan territory to demonstrate the efficiency of this updating method and draw perspectives for further applications. [ABSTRACT FROM AUTHOR]

A review on the historical evolution of seismic hazard maps in Turkey is followed by summarizing the important aspects of the updated national probabilistic seismic hazard maps. Comparisons with the predecessor probabilistic seismic hazard maps as well as the implications on the national design codes conclude the paper. [ABSTRACT FROM AUTHOR]

The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org). [ABSTRACT FROM AUTHOR]