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In relation to its rapid infrastructure expansion, exemplified by projects like the Najran Valley Dam or the rehabilitation of agricultural terraces, Saudi Arabia stands out among the Arabian Gulf nations. To mitigate the earthquake-related risks effectively, it is imperative to conduct an exhaustive analysis of its natural hazards. The southwesternmost region of Saudi Arabia is the main subject area of this study for the probabilistic seismic hazard assessment (PSHA), which aims to identify the peak ground acceleration (PGA) and spectral acceleration (SA) values. The investigation encompasses a 10% and 5% probability of occurrence over a 50-year exposure time for both B/C and C NEHRP soils. In order to take into account the earthquake activity that takes place in the vicinity of the Red Sea Rift, which in fact may have an impact on the seismic hazard in this active tectonic region, different seismic source zones were especially designed for this evaluation. Various characteristics such as the uncertainties related to the b-value, the expected maximum magnitude, and different ground motion prediction equations (GMPEs) were integrated using a logic tree scheme. Additionally, regression relationships between the computed ground motion values were established, and a novel design response spectrum was developed and recommended for several cities. Regarding the key findings, it is significant to highlight that the seismic hazard decreases towards the northeast, when moving away from the Red Sea Rift, confirming anticipated trends where proximity to the rift corresponds to increased seismic hazard. Notably, cities such as Farasan Island, Jazan, Al Qunfundhah, Al Lith and Al Birk present the highest observed hazard values among all the cities analyzed. For these cities, the obtained maximum SA values for both 475 and 975 years under B/C site conditions are as follows: 0.268 g and 0.412 g, 0.121 g and 0.167 g, 0.099 g and 0.150 g, 0.083 g and 0.135 g, and 0.066 g and 0.118 g, respectively. These results emphasize the crucial necessity of adequately evaluating and thoroughly updating the seismic hazard inherent to these particular areas to enhance the risk reduction and disaster readiness initiatives. [ABSTRACT FROM AUTHOR]

Ground-motion models (GMMs) are frequently used in engineering seismology to estimate ground motion intensities. The majority of GMMs predict the response spectral ordinates (such as spectral acceleration) of a single-degree-of-freedom oscillator because of their common application in engineering design practices. Response spectra show how an idealized structure reacts to applied ground motion; however, they do not necessarily represent the physics of ground motion. The functional forms of the response spectra GMMs are built around ideas taken from the Fourier spectral concept. Assuming the validity of Fourier spectral concepts in the response spectral domain could cause physically inexplainable effects. In this study, using a mixed-effects regression technique, we introduce four models capable of predicting the Fourier amplitude spectrum that investigates the impact of incorporating random-effect event and station terms and variations in using a mixed-effects regression technique in one or two steps using truncated dataset or all data (nontruncated dataset). All data consists of 2581 three-component strong ground motion data resulting from 424 events with magnitude ranging from 4.0 up to 7.4, from 1976 to 2020, and 706 stations. The truncated dataset's records, events, and stations are reduced to 2071, 408, and 636, respectively. As part of this study, we develop GMMs to predict the Fourier amplitude spectrum for the Iranian plateau within the frequency range of 0.3–30 Hz. We adopted simple, functional forms for four models, and we included a limited number of predictors, namely Mw (moment magnitude), Rjb (Joyner–Boore distance), and VS30 (time-averaged shear-wave velocity in the top 30 m). Due to statistical analyses, the style-of-faulting term was excluded from the final functional forms. The robustness of the derived models is indicated by unbiased residual variation with predictor variables. [ABSTRACT FROM AUTHOR]

Here we present a deaggregation appraisal conducted for 15 selected significant cities in Western Mexico, for four oscillation periods (PGA, SA (0.2 s), SA (1.0 s), and SA (2.0 s)), also considering a different input for the soil condition (for B, B/C and C NEHRP site classes), and for two return periods (475 and 975 years). This study is based on a previous complete recently published seismic hazard evaluation for the region. An area source model consisting of thirty-seven seismic sources has been used alternatively in a logic tree with a spatially smoothed seismicity model for the same region. The obtained hazard deaggregation results prove that for most of the studied cities –those located along the Pacific coast–, nearby seismic sources are contributing most to the seismic hazard at the studied location, especially for lower periods (PGA and SA (0.2 s)). However, for a few cities far from the Middle America Trench, distant large-magnitude earthquakes contribute more to the seismic hazard, especially at larger spectral periods (SA (1.0 s) and SA (2.0 s)). Additionally, this study shows that the differences in the soil conditions for the computed return periods, have a little influence on the obtained deaggregation results. [ABSTRACT FROM AUTHOR]

This paper estimates a correlation model and joint distribution model of spectral accelerations of vertical ground motions based on the NGA-West2 ground motion database. The correlation model calculated via BC16 vertical GMPE in this study is compared with those published models via other vertical NGA-West2 GMPEs. It is verified that the calculated residuals of vertical ground motions at multiple periods follow the multivariate normal distributions via both a qualitative validation method and a set of quantitative validation methods. The correlation model and the joint distribution model of vertical spectral accelerations are the theoretical basis for research on the joint occurrence of spectral accelerations of vertical ground motions, and an example of applied research on joint occurrence of spectral accelerations of vertical ground motions is studied: the conditional mean spectrum of vertical ground motions. Finally, the effects of different vertical correlation models and ground motion prediction equations on vertical conditional spectra are investigated for wide application of the correlation model and the joint distribution model of spectral accelerations of vertical ground motions. [ABSTRACT FROM AUTHOR]

The new trend toward modern earthquake-resistant design of buildings based on nonlinear dynamic analysis accounting for peak and energy demands requires efficient ground motion record selection procedures. For this reason, in the present work, two record selection strategies based on acceleration and input energy spectrum considering the spectral shape via Np are presented. Furthermore, both record selection strategies are optimized by means of four artificial intelligence (AI) techniques: Genetic Algorithms (GA), Harmony Search (HS), Particle Swarm Optimization (PSO) and Vibrating Particle System (VPS). In particular, the effectiveness of each AI approach toward the best set of ground motion records for nonlinear dynamic analysis is compared. For this aim, spectral acceleration and input energy design spectra were considered, as well as 1024 seismic records obtained from the Pacific Earthquake Engineering Research Center. For all the AI or meta-heuristic approaches, the fitness function used is focused on minimizing the difference between the average spectrum of eleven ground motion records and the design spectrum using the well-known parameter Np, which represents the spectral shape in a range of periods. In addition, a penalization is included for those spectra with very large or low demands. Thus, 24 sets of eleven seismic records that can be used for nonlinear dynamic analysis of structures with a fundamental period of vibration of 0.6, 1.2 and 1.8 seconds were obtained and purposes. The results demonstrate the ability of the two records selection strategies analyzed and the four meta-heuristic procedures, achieving results quickly and simply regardless of the type of demands, intensities and periods considered. Finally, it is concluded that the VPS algorithm is better in comparison with GA, HS, and PSO since it obtains superior results in almost all the selected cases. [ABSTRACT FROM AUTHOR]

The new trend toward modern earthquake-resistant design of buildings based on nonlinear dynamic analysis accounting for peak and energy demands requires efficient ground motion record selection procedures. For this reason, in the present work, two record selection strategies based on acceleration and input energy spectrum considering the spectral shape via Np are presented. Furthermore, both record selection strategies are optimized by means of four artificial intelligence (AI) techniques: Genetic Algorithms (GA), Harmony Search (HS), Particle Swarm Optimization (PSO) and Vibrating Particle System (VPS). In particular, the effectiveness of each AI approach toward the best set of ground motion records for nonlinear dynamic analysis is compared. For this aim, spectral acceleration and input energy design spectra were considered, as well as 1024 seismic records obtained from the Pacific Earthquake Engineering Research Center. For all the AI or meta-heuristic approaches, the fitness function used is focused on minimizing the difference between the average spectrum of eleven ground motion records and the design spectrum using the well-known parameter Np, which represents the spectral shape in a range of periods. In addition, a penalization is included for those spectra with very large or low demands. Thus, 24 sets of eleven seismic records that can be used for nonlinear dynamic analysis of structures with a fundamental period of vibration of 0.6, 1.2 and 1.8 seconds were obtained and purposes. The results demonstrate the ability of the two records selection strategies analyzed and the four meta-heuristic procedures, achieving results quickly and simply regardless of the type of demands, intensities and periods considered. Finally, it is concluded that the VPS algorithm is better in comparison with GA, HS, and PSO since it obtains superior results in almost all the selected cases. [ABSTRACT FROM AUTHOR]

The complex tectonic position and the long history of the devastating earthquakes with massive casualties and socio-economic damages have highlighted the importance of proper seismic hazard assessment for the eastern Himalaya syntaxis region. Here, probabilistic seismic hazards are computed combining the area, linear and smooth grid seismogenic source models. The surface topography and the site effects are incorporated to thousands of 0.1° × 0.1° grid cells. Uniform moment magnitude (MW) in declustered catalog is used. The mean seismicity rate, the b-value and the expected maximum magnitude are estimated using the Maximum Likelihood Algorithm. Two sets of ground motion prediction equations for shallow crustal and subduction interface tectonic regimes are assigned to every source model by utilizing a logic tree to reduce the epistemic uncertainties in hazard calculation. The peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2 s and 1.0 s are estimated for 2% and 10% probabilities of exceedance in 50 years. The hazard maps show a wide range of spatio-temporal variation in PGA and SA values. The maximum and minimum PGA values are 0.18 g and 0.70 g, respectively for 10% probability of exceedance. High hazardous zones are associated with the continental plate collision beneath the Assam Syntaxis. Medium hazard is estimated at Namche Barwa syntaxis. This analysis suggests the integration of actual site conditions, well developed ground motion prediction equations and multiple source models through logic tree to evaluate the comprehensive seismic hazards for tectonically complex regions like the Himalaya orogen. [ABSTRACT FROM AUTHOR]

Basin presence is believed to affect the ground surface response due to earthquakes, particularly in areas around the basin edge. Previous studies showed that 1-D and 2-D wave propagation analyses resulted in significant differences in amplification at the basin edge. However, the link between 1-D and 2-D responses has not been studied for engineering practices. In practical application, seismic studies were commonly performed using 1-D analysis, for example, to develop a city micro-zonation map. Based on practical considerations, it is necessary to estimate the scaling factor for the 1-D analysis by considering the basin presence, particularly for one containing soft soil. There are three stages carried out in this study. The first stage: collecting data on some basin geometries for the 2-D modeling references and then defining selected site class and input motions. The second stage: modeling 1-D and 2-D wave propagation using D-MOD and Fast Lagrangian Analysis of Continua (FLAC), respectively. The third stage: comparing spectral acceleration resulting from the 1-D and 2-D analyses to obtain the scaling factors. This research studied and reported the relationship between PGA values varied as 0.2 g, 0.3 g, 0.4 g, and 0.5 g, basin geometry (e.g., the angle was set to 5°, 10°, 15°, 30°, and 45°, with depth and width variations of 0.0125, 0.025, 0.05, 0.075, 0.1, 0.2, and 0.4, while the basin width was adjusted to 500 m, 1 km, 2 km, and 4 km), and the spectral acceleration in several observation points on the ground surface. Based on this evaluation, a series of scaling factors are proposed. These factors can be used for spectral acceleration from available hazard maps, commonly developed based on 1-D analysis. The application example of this scaling factor is presented in this study, using the Bandung Basin case. [ABSTRACT FROM AUTHOR]

The effect of seismic waves on structures during an earthquake varies depending on local ground conditions. This study is dedicated to determining the seismic site characterization of Kovancılar district in the city of Elazığ, Turkey, whose location is close (5 km) to the East Anatolian Fault Zone (EAFZ), one of the most active fault zones all around globe. For this purpose, 1-D equivalent linear soil behavior analyzes were performed using 28 geotechnical drilling and 20 multi-channel surface wave (MASW) test data in the study area. The results of these analyses indicated the peak ground acceleration (PGA) values in Kovancılar ranged between 0.41 and 0.68 g, while high PGA values were observed in the region of alluvial soils in the south of the district. The acceleration spectra obtained from the analyses on three different locations were compared to the Turkish Building Seismic Regulation 2018 (TBSR 2018) and Eurocode 8 (EC-8 2004) design spectra. For some periods, the acceleration values in the site-specific spectra were observed to exceed the related values in the TBSR 2018 ZC and ZD design spectra. In addition, ground amplification, PGA, and spectral acceleration (Sa) maps with 0.2–1 s periods were created for the study area. With the evaluation of the obtained parameters, the north of the region was established to be more suitable for multi-story buildings, while the northeast, east, and southeast regions being more suitable for low-rise buildings. [ABSTRACT FROM AUTHOR]

High temperatures occur that increase over time due to the product emerging in buildings. The stiffness and mass of reinforced concrete structural elements also decrease over time due to this high temperature. Management voting periods used in the analysis of the earthquake forces of the structure and many values calculated accordingly are changing. You need to re-introduce the mass and stiffness matrices in the relations given in TS-EN 1992 1-2 for data on material properties at high temperature. Considering this regime and the temperature-dependent changes in the elastic modulus, in the first periods of a selected reinforced concrete maintenance, the changes in the extreme elastic design spectral accelerations, base shear forces and displacements for a selected node change. [ABSTRACT FROM AUTHOR]

The Makiling Botanic Gardens (MBG) is an educational and eco-tourism site located within the vicinity of Mount Makiling, a dormant volcano susceptible to landslides, and located less than 20 km away from at least two tectonic faults. The study assessed the seismic-induced landslide hazards in the recreational area of MBG mainly based on three parameters: factor of safety (FS), yield acceleration (ay), and slope displacement (Dn). Dynamic Cone Penetration Test (DCPT) served as the primary method for obtaining the shear strength of the soil within the area. Meanwhile, other relevant parameters, including material unit weight and internal angle of friction, were determined through laboratory testing, correlations, and available data and models. Moreover, the Peak Ground Acceleration (PGA) and Spectral Acceleration (SA) values were obtained through an interpretation of a probabilistic seismic hazard analysis (PSHA) study of the Philippines. Using the ArcGIS software, an FS map, yield acceleration map, and slope displacement map were generated. Results showed that the slopes within the area exhibit static stability. However, in the event of an earthquake, it is expected that the amplified PGA will exceed the expected yield acceleration values of the slopes in some parts of the recreational area, which could result in dynamic instability and slope displacements as high as 130 mm. Thus, the recreational area of MBG possesses some susceptibility towards a seismic-induced landslide. [ABSTRACT FROM AUTHOR]

In relation to its rapid infrastructure expansion, exemplified by projects like the Najran Valley Dam or the rehabilitation of agricultural terraces, Saudi Arabia stands out among the Arabian Gulf nations. To mitigate the earthquake-related risks effectively, it is imperative to conduct an exhaustive analysis of its natural hazards. The southwesternmost region of Saudi Arabia is the main subject area of this study for the probabilistic seismic hazard assessment (PSHA), which aims to identify the peak ground acceleration (PGA) and spectral acceleration (SA) values. The investigation encompasses a 10% and 5% probability of occurrence over a 50-year exposure time for both B/C and C NEHRP soils. In order to take into account the earthquake activity that takes place in the vicinity of the Red Sea Rift, which in fact may have an impact on the seismic hazard in this active tectonic region, different seismic source zones were especially designed for this evaluation. Various characteristics such as the uncertainties related to the b-value, the expected maximum magnitude, and different ground motion prediction equations (GMPEs) were integrated using a logic tree scheme. Additionally, regression relationships between the computed ground motion values were established, and a novel design response spectrum was developed and recommended for several cities. Regarding the key findings, it is significant to highlight that the seismic hazard decreases towards the northeast, when moving away from the Red Sea Rift, confirming anticipated trends where proximity to the rift corresponds to increased seismic hazard. Notably, cities such as Farasan Island, Jazan, Al Qunfundhah, Al Lith and Al Birk present the highest observed hazard values among all the cities analyzed. For these cities, the obtained maximum SA values for both 475 and 975 years under B/C site conditions are as follows: 0.268 g and 0.412 g, 0.121 g and 0.167 g, 0.099 g and 0.150 g, 0.083 g and 0.135 g, and 0.066 g and 0.118 g, respectively. These results emphasize the crucial necessity of adequately evaluating and thoroughly updating the seismic hazard inherent to these particular areas to enhance the risk reduction and disaster readiness initiatives.

AbstractNorth East India is a highly seismically active zone of India due to the collision tectonics between the Indian and the Eurasian plate in the north and subduction tectonics along the Indo-Myanmar range (IMR) in the east. It is utmost important to investigate the seismicity of this region along with uniform hazard spectra (UHS). In this paper, seismic hazard study has been performed at the Silchar district headquarters of Assam state, located in North East India. The earthquake data have been collected from various agencies from 1762 to 2020 and the fault data has been collected from seismotectonic atlas (SEISAT). Earthquake and fault data are superimposed on the Northeast India map using MapInfo software. The fault zone is defined based upon the earthquake’s density near the fault. Seismicity parameters and maximum magnitude have been estimated using Gutenberg-Richter (G-R) relationship. The best-fitted ground motion equation is considered. The outcome is represented in terms of controlling source, seismic hazard curve and UHS for Silchar city with varying ground motions. Finally, the results are presented as PGA based upon DSHA and PSHA methods. The effect of Importance Factor (I) and Response reduction factor (R) have been investigated by comparing UHS with IS: 1893-2016 code response spectra.

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Ground motion intensity measures (IMs) play a significant role in earthquake engineering, especially during ground motion selection for nonlinear response history analyses, dynamic shake table tests, and probabilistic seismic engineering. Conventional IMs are not capable of accounting for the duration-related cumulative plastic damage, the frequency content of the ground motions, and the hysteretic behavior of the structural members which can be considered inherently by seismic energy-based IMs. However, many efforts have been made for conventional IMs to relate them to the structural response. An empirical correlation study between energy-based and conventional IMs is required to benefit from these efforts. To this end, constant ductility seismic input energy and hysteretic energy imparted to diverse single-degree-of-freedom (SDoF) systems were calculated for near-field earthquake records. The empirical correlations of the energy-based IMs with conventional spectrum-based, peak amplitude-based, and cumulative-based IMs have been investigated based on the response history analyses. Further, considering different constant ductility levels, predictive models between energy parameters and spectral acceleration were suggested. Hence, ground motion characteristics reflected by the input and hysteretic energy can be explicitly considered in performance-based earthquake engineering applications. [ABSTRACT FROM AUTHOR]

In the current study, ground motion models (GMMs) are derived using the European Strong Motion (ESM) database for pseudo‐spectral acceleration (PSA), peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD), cumulative absolute velocity (CAV), arias intensity (Ia), and significant duration. In addition to addressing random effects associated with ground motion regression, such as inter‐event, inter‐site, inter‐locality, and inter‐region variabilities, the current study also aims at reducing the standard deviations (STDs) of the GMMs through development of a hybrid non‐parametric GMM. The hybrid model is derived through an ensemble‐weighted method of five non‐parametric machine learning models: shallow neural network, deep neural network (DNN), gated recurrent unit (GRU), support vector, and random forest (RF) regression techniques; with weights based on model performances. The resulting hybrid model, which also accounts for epistemic uncertainty, is compared against other regional models and is found superior for all output variables. The inter‐event, inter‐site, inter‐locality, and inter‐region deviations, and total ergodic sigma of PSA for the ensemble model lies between 0.3164–0.4478, 0.4156–0.5339, 0.1449–0.3687, 0.0819–0.2421, and 0.668–0.8545, respectively. The coefficient of determination (R2) between predicted and recorded values lies between 0.8435–0.9114 for all the output variables. [ABSTRACT FROM AUTHOR]

Over the years, in the study of earthquakes, there has been a shift in the use of current force-based methodology to performance-based methodology. In this study, an attempt has been made to study the seismic performance of regular and vertically irregular structures by making use of time history analysis to establish seismic fragility estimates. To perform the analysis, three Indian strong ground motions have been considered by varying soil conditions. Comparison has been made in terms of displacement and spectral accelerations for both regular and irregular structures with different soil conditions. The study highlights the importance of obtaining performances in terms of Operational Phase (OP), Immediate Occupancy (IO), Damage Control (DC), Life Safety (LS), and Collapse Prevention (CP). The seismic vulnerability of buildings has been obtained treating the foundation as isolated footing in terms of damages by taking strong ground motion data into consideration to perform performance-based analysis of structures with different soil conditions. [ABSTRACT FROM AUTHOR]

Probabilistic Seismic Hazard Assessment (PSHA) was carried out for the administrative region of Attica (Greece). Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) values were calculated for return periods of 475 and 950 years for five sub-areas covering the entire region. PGA hazard curves and Uniform Hazard Spectra (UHS) in terms of spectral acceleration (Sa) values were generated for Athens, Methana, and the capitals of each island of Attica (Salamina, Aegina, Poros, Hydra, Spetses, Kythira, and Antikythira). Area sources were adopted from the Euro-Mediterranean Seismic Hazard Model 2013 (ESHM13) and its update, ESHM20, taking into account both crustal and slab tectonic environments. Ground Motion Prediction Equations (GMPEs) proposed for the Greek territory were ranked for PGA and PGV. Each GMPE was reconstructed as a weighted model, accounting for normal and non-normal focal mechanisms for each area source. PGA, PGV, and Sa values were computed using a logic tree, integrating the seismotectonic models as major branches and sub-logic trees, comprised of multiple ranked GMPEs for each area source, as minor branches. The results showed higher seismic hazard values in sub-areas near the Gulf of Corinth and the slab interface, which could indicate a need to revise the active building code in Attica. [ABSTRACT FROM AUTHOR]

Strong ground motions caused by earthquakes with magnitudes ranging from 3.5 to 6.9 and hypocentral distances of up to 300 km were recorded by local broadband stations and three-component accelerograms within Georgia’s enhanced digital seismic network. Such data mixing is particularly effective in areas where strong ground motion data are lacking. The data were used to produce models based on ground-motion prediction equations (GMPEs), one benefit of which is that they take into consideration information from waveforms across a wide range of frequencies. In this study, models were developed to predict ground motions for peak ground acceleration and 5%-damped pseudo-absolute-acceleration spectra for periods between 0.01 and 10 s. Short-period ground motions decayed faster than long-period motions, though decay was still in the order of approximately 1/r. Faulting mechanisms and local soil conditions greatly influence GMPEs. The spectral acceleration (SA) of thrust faults was higher than that for either strike-slip or normal faults but the influence of strike-slip faulting on SA was slightly greater than that for normal faults. Soft soils also caused significantly more amplification than rocky sites.

Tasarım aşamasında yapılara etkiyecek deprem yüklerinin belirlenebilmesi için statik ve dinamik analiz yöntemleri kullanılmaktadır. Statik analiz yöntemlerinden biri de tasarım ivme spektrumlarının hesaplanmasıdır. 2007 yılından itibaren kullanılmakta olan Deprem Bölgelerinde Yapılacak Yönetmelik (DBYBHY) 2019 yılından itibaren kaldırılıp yerine Türkiye Bina Deprem Yönetmeliğinin kullanılması zorunlu hale getirilmiştir. Bu çalışmada, her iki yönetmeliğe göre tanımlanan spektral ivme değerleri ile zemin köşe periyotları Eskişehir’deki farklı zemin sınıfları için karşılaştırılmıştır. Çalışmada, Eskişehir il merkezine ait 40 adet sondaj verisi kullanılarak hesaplamalar gerçekleştirilmiştir. DBYBHY 2007’de Eskişehir için tanımlanan zemin köşe periyotları aynı yerel zemin sınıfı için sabit iken, TBDY 2018 için bu değerler, sondajın yapıldığı bölgeye bağlı olarak değişmektedir. Bu nedenle, TBDY 2018’den elde edilen zemin köşe periyotlarının aynı zemin sınıfı için bile olsa küçük farklılıklar gösterirken, aynı yerel zemin sınıfı için spektral ivmelerde meydana gelen değişimin daha belirgin olduğu tespit edilmiştir.

Abstract Building an earthquake early warning (EEW) network requires the installation of seismic instruments around the seismogenic zone. Using low-cost sensors to build a seismic network for EEW and to generate shakemaps is a cost-effective way in the field of seismology. The National Taiwan University (NTU) network employing 762 P-Alert low-cost sensors based on micro-electro-mechanical systems (MEMS) technology is operational for almost the last 10 years in Taiwan. This instrumentation is capable of recording the strong ground motions of up to ± 2 g and is dense enough to record the near-field ground motion. The NTU system has shown its importance during various earthquakes that caused damage in Taiwan. Although the system is capable of acting as a regional as well as an onsite warning system, it is particularly useful for onsite warning. Using real-time seismic signals, each P-Alert device provided a 2–8 s warning time for the near-source earthquake regions situated in the blind zone of the Central Weather Bureau (CWB) regional EEW system, during the 2016 $${{{M}}}_{{{w}}}$$ M w 6.4 Meinong and 2018 $${{{M}}}_{{{w}}}$$ M w 6.4 Hualien earthquakes. The shakemaps plotted by the P-Alert dense network help to assess the damage pattern and act as key features in the risk mitigation process. These shakemaps are delivered to the intended users, including the disaster mitigation authorities, for possible relief purposes. Currently, the P-Alert network can provide peak ground acceleration (PGA), peak ground velocity (PGV), spectral acceleration ( $${S}_{a}$$ S a ) at different periods, and CWB intensity shakemaps. Using shakemaps, it is found that PGV is a better indicator of damage detection than PGA. Encouraged by the performance of the P-Alert network, more instruments are installed in Asia-Pacific countries.

It is well known that seismic hazard assessment should be implemented to design infrastructures in an earthquake-prone area such as Bengkulu. This paper presents local seismic hazard maps based on the response spectra of stiff and very dense soils in Bengkulu city, Indonesia. We collect the soil data and conduct the seismic wave propagation. The input motion for wave propagation analysis is generated from the spectral acceleration curves of stiff and dense soils. Various ground motion parameters such as peak ground acceleration, short-period and long-period spectral accelerations, and amplification factors are presented in microzonation maps. The results show that the peak ground acceleration in the study area ranges from 0.2 to 0.8 g, while the spectral acceleration varies between 0.5–1.5 g and 0.4–0.8 g for periods of 0.2 and 1 s, respectively. The amplification factor of the site is observed to vary from 0.5 to 1.6. Considering other spectral accelerations in Bengkulu, the spectral acceleration design shows a good performance. The results indicate the site characteristics of Bengkulu city, which can provide engineers with site class for structural building design.

Correlating different intensity measures (IMs) enables the joint consideration of multiple IMs in various performance-based earthquake engineering applications, such as ground motion selection. The correlations between the spectral input energy and spectral accelerations have not been previously examined. This study develops a correlation model quantifying the uncertainties due to GMPE selection and a finite sample size. The results show a strong correlation between the spectral amplitudes at the same period, and the correlation decreases as the period difference increases. With the proposed model, ground motion characteristics reflected by the input energy can be explicitly considered in performance-based earthquake engineering applications. [ABSTRACT FROM AUTHOR]

In the present work, the seismic response of a reinforced concrete building representative of modern multi-family residences of medium height in the southern zone of Peru was estimated. This region was considered because we can find growing urban areas with a variety of altitudes and consequently different seismic conditions, which can be found in the three countries of the case study, in accordance with the seismic standards of the Pacific area corresponding to the current official directives of Peru (E.030, 2018), Chile (NCh433, 2012) and Ecuador (NEC, 2015), using spectral modal analysis with the purpose of highlighting the most relevant aspects in the standards and identifying possible missing parameters that prominently influence the structural demand. The analysis included the estimation of shear forces, spectral acceleration and relative inter-story displacement, including variables such as seismic zoning, soil typology, category of use, structural system, among others; considering the approach of a uniform scheme for the comparison of limits between the relative inter-story displacement established in each standard. The process was carried out from numerical models of a 10-story reinforced concrete building consisting of frames and structural walls; finding, among others, that the highest acceleration demand at surface level in coastal regions for a rocky soil (Vs ≥ 900 m/s) corresponds to Peru, followed by Ecuador and Chile. It is concluded in general, that the highest demands and the most restrictive limits for different seismic zones and different soil conditions correspond to the regulatory provisions of Peru. [ABSTRACT FROM AUTHOR]

This study aims to reveal the dynamic behavior of soil layers due to a possible earthquake in the Batman city center. The one-dimensional equivalent linear soil behavior analysis method proposed in the Turkish Building Earthquake Code (TBEC) 2018 was used in the analyses. These analyses were performed with DEEPSOIL 6.1 software to assess the soil conditions and their behavior under the influence of earthquakes. Eleven different acceleration records were used for each drilling log, as suggested in TBEC (2018). Geotechnical and geophysical data were obtained from multi-channel analysis of surface wave (MASW) measurements taken at six locations in the northern part of Batman, Turkey, to determine the dynamic behavior of the soil and guide new constructions. The maximum ground acceleration values calculated from the ground response analyses vary between 0.15 g and 0.24 g. The results showed that low-shear waved or soft soil profiles had higher amplification values at periods above 0.5 s than hard/tight soil profiles. Consequently, as soil hardness decreased, the amplification ratios increased. The soil amplification was observed at different values depending on the local soil properties for this study. Additionally, it has been observed that some earthquakes in the study area have higher spectral acceleration rates than those given in the TBEC (2018) and Eurocode 8 at certain periodical intervals. This situation reveals that if an earthquake is similar to the earthquake selected within the study’s scope, building stock in the northern and northeastern parts of Batman city may suffer more damage than expected. [ABSTRACT FROM AUTHOR]

This research paper focuses on the development of ground motion models for simulating the main characteristics of recorded earthquake accelerograms induced by geothermal power plants (GPPs) operation. In this regard, firstly, a worldwide database for the GPP-induced earthquakes is gathered, containing 110 events and 664 recorded accelerograms. All the data are processed using a combined denoising method. Afterward, their main seismic characteristics are studied statistically, in both horizontal and vertical directions. Finally, different sets of ground motion models are developed for simulating the ground motion peak values, duration, 5% damped spectral acceleration and velocity in horizontal, and vertical directions. [ABSTRACT FROM AUTHOR]

A fault called as Lembang Fault is known as one of the most potential faults in West Java of Indonesia that could trigger earthquakes with magnitude up to Mw 7.0, especially in Bandung Region. This study presents analysis of ground response of Bandung Regency subsoils due to predicted earthquake triggered by Lembang Fault, West Java Province, Indonesia. Site investigation is conducted in the study area. The ground motion analysis is conducted to predict potential ground motion that could happen in the study area. The spectral matching method is employed to generate ground motion in the study area. Furthermore, one-dimensional seismic ground response analysis is performed to observe site response during earthquake. The results show that several sites could undergo amplification and de-amplification. If a Mw 7.0 earthquake happens, the damage intensity level varied from VIII to X could happen. The results also indicate that spectral acceleration at ground surface tends to be critical at long period. Therefore, the implementation of seismic design code for earthquake resistance design should be concerned in the study area. In general, the result of this study could deliver a recommendation to local government to consider earthquake in the study area. [ABSTRACT FROM AUTHOR]

The strong ground motion effect is amplified or de-amplified due to the change in subsoil condition. Local soil properties prediction is critical for earthquake-safe areas and the earthquake hazard assessment of existing structures. This study was carried out with time-domain 1D Nonlinear analysis to understand the soil response characteristics of the Arifiye district. In this sense, geotechnical drilling at 47 points and surface wave analysis at 44 points were performed. Site response profiles in the study area were analyzed with the DeepSoil program for Mw:7.0 1967 Mudurnu and Mw:7.4 1999 Kocaeli earthquake scenarios. Peak spectral acceleration (Pga) and spectral acceleration (Sa) values were determined in the analysis of the Mudunu scenario as 0.11–0.24 g and 0.44–1 g, respectively. The Kocaeli scenario's Pga and Sa distribution were obtained in a wide range of 0.2–0.56 g and 0.47–2.3 g, respectively, compared to the Mudurnu scenario. Especially in the Mw:7.4 model, high Pga (> 0.3 g) and Sa (> 1 g) values were obtained in the uncemented units located north of the study area. Kocaeli scenario results showed that the spectral accelerations at the surface in soil groups D and E were higher than the Turkish Building Earthquake Code building requirements. It is necessary to update the earthquake design spectra site-specific. The results clearly showed the effect of ground conditions and strong ground motion selection on earthquake-resistant building design. [ABSTRACT FROM AUTHOR]

This article presents a ground motion database for California and its close surroundings (i.e. areas near the border in Nevada, Oregon, and Arizona) from earthquakes between 1999 and 2021. This data set includes events with magnitudes larger than 3.2 and focal depths less than 40 km, and it is available on DesignSafe. Ground motion records and events included in this data set are collected from 65 different seismic networks and processed with an automated software tool called gmprocess, which was developed by the United States Geological Survey (USGS). Path measures such as rupture distance and epicentral distance are computed, 5%-damped spectral accelerations, duration metrics, and other ground motion intensity measures (IMs) are provided for records that pass the quality assurance check performed by the gmprocess toolkit. The quality of processed ground motions is also screened by using outlier detection algorithms and a multiple wave-train arrivals identification algorithm. In addition, site metadata are provided, including wave velocity information (from proxy-based time-averaged shear-wave velocity for the top 30 m, Vs30, and from Pand S-wave measured velocity profiles when available), predominant frequency measured from microtremor-based horizontal-to-vertical ratios (mHVSR), and sitespecific (high-frequency spectral decay) k0 values computed from multiple ground motions recorded at sites when available. The final database contains 287,804 threecomponent ground motions recorded at 3709 stations from 2641 earthquakes with magnitudes and distances ranging from 3.2 to 7.2 and 0.15 to 335 km, respectively. This ground motion database contributes to advancing both engineering seismology studies and earthquake engineering applications in shallow crustal tectonic settings. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of site-specific analysis in observing the performance of a monumental building in Bengkulu City, Indonesia that is called the Lighthouse View Tower. This building was inaugurated in 2012. So far, it is still necessary to present the issue related to the performance of the building after 10 years. The objective of this study is to observe the performance of the building after the strong earthquake occurred. This study is first conducted by performing a site investigation. The information related to the soil profile; ground motion of the strong earthquake that occurred in Bengkulu City is collected. Furthermore, the site-specific response analysis is conducted on the site where the building stands. The results from site-specific response analysis, i.e. the actual spectral acceleration is obtained. The spectral acceleration is then used as the input parameter for finite element analysis to observe the performance of the building. The main goal of this study is to observe the structure health condition. The results show that during the strong earthquake, the structure of the view tower is still reliable and in good condition. Concern regarding the building maintenance should be emphasized. In general, the method implemented in this study could be used as the method to assess the performance of structures in other areas.

The spectral accelerations (Sa), which are widely used as ground motion inputs in structural seismic designing, are significantly affected by local site conditions classified by near-surface geology. A novel approach of quantifying the scaling ratios for Sa on site class I, II, III, and IV under the site condition classifications in Chinese seismic codes, was proposed. In this integrated approach, the scaling ratios for Sa on each site class were subordinated to three constituents, i.e., scaling ratios for peak ground acceleration (PGA), scaling ratios for PGA-normalized Sa, and non-linear decay exponents. The scaling ratios for peak ground acceleration were derived from recent studies and numerical simulations of 1,138 borehole models in China, the scaling ratios for PGA-normalized Sa were derived from 3,584 strong motion records in NGA West two database, and the non-linear decay exponents were derived from about 140 thousand borehole observation data recorded by KiK-net. Consequently, this approach was solidly based on statistics of observation data in company with numerical simulations, which resulted in more reasonable and more reliable scaling ratios for Sa caused by the seismic site effect under site condition classifications in China.

Building an earthquake early warning (EEW) network requires the installation of seismic instruments around the seismogenic zone. Using low-cost sensors to build a seismic network for EEW and to generate shakemaps is a cost-effective way in the field of seismology. The National Taiwan University (NTU) network employing 762 P-Alert low-cost sensors based on micro-electro-mechanical systems (MEMS) technology is operational for almost the last 10 years in Taiwan. This instrumentation is capable of recording the strong ground motions of up to ± 2 g and is dense enough to record the near-field ground motion. The NTU system has shown its importance during various earthquakes that caused damage in Taiwan. Although the system is capable of acting as a regional as well as an onsite warning system, it is particularly useful for onsite warning. Using real-time seismic signals, each P-Alert device provided a 2–8 s warning time for the near-source earthquake regions situated in the blind zone of the Central Weather Bureau (CWB) regional EEW system, during the 2016 M w 6.4 Meinong and 2018 M w 6.4 Hualien earthquakes. The shakemaps plotted by the P-Alert dense network help to assess the damage pattern and act as key features in the risk mitigation process. These shakemaps are delivered to the intended users, including the disaster mitigation authorities, for possible relief purposes. Currently, the P-Alert network can provide peak ground acceleration (PGA), peak ground velocity (PGV), spectral acceleration ( S a ) at different periods, and CWB intensity shakemaps. Using shakemaps, it is found that PGV is a better indicator of damage detection than PGA. Encouraged by the performance of the P-Alert network, more instruments are installed in Asia-Pacific countries. [ABSTRACT FROM AUTHOR]

In the present study, the attenuation relationships of horizontal and vertical peak ground acceleration and 5%-damped spectral acceleration, suitable for the northern region of Iran (Alborz Zone), are presented. The dataset contains 308 three-component records from 104 events with moment magnitudes between 4.5 and 7.6 and hypocentral distances from 10 to 200 km. Site conditions of the stations have been classified into two categories, rock and soil. To determine the unknown constants of the relations, one-step nonlinear regression analysis was used. Finally, it was found that the proposed attenuation relationships show good compatibility with a number of past well-known studies. [ABSTRACT FROM AUTHOR]

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Site amplification factors in National Building Codes are typically specified as a function of the average shear wave velocity over the first 30 m (Vs30) or site class (A, B, C, D and E) for defined ranges of Vs30 and/or ranges of depth to bedrock. However, a single set of amplification factors may not be representative of site conditions across the country, introducing a bias in seismic hazard and seismic risk analyses. This is exemplified by significant differences in geological settings between East and West coast locations in North America. Western sites are typically characterized by lower impedance contrasts between recent surface deposits and bedrock in comparison to Eastern sites. In North America, site amplification factors have been derived from a combination of field data on ground motions recorded during West Coast earthquakes and numerical models of site responses that are meant to be representative of a wide variety of soil profiles and ground motions. The bias on amplifications and their impact on seismic hazards is investigated for the Montreal area, which ranks second for seismic risks in Canada in terms of population and hazard (PGA of 0.25 g for a 2475 years return period). Representative soil profiles at several locations in Montreal are analyzed with 1-D site response models for natural and synthetic ground motions scaled between 0.1 to 0.5 g. Since bedrock depths are typically shallow (s30 and site fundamental frequency and compared to those of the National Building Code of Canada (2015). The results of the study indicate that there are large uncertainties associated with these parameters due to variability in soil profiles, soil properties and input seismic ground motions. Average and confidence intervals for the mean and for predictions of amplification factors are calculated for each site class to quantify this uncertainty. Amplifications normalized relative to class C are obtained by accounting for the correlation between site class amplifications for given ground motions. Non-linearity in the analysis of equivalent linear 1-D site response is taken into account by introducing the non-linear G/Gmax and damping ratios curves. In this method, it is assumed that the shear strain compatible shear modulus and damping ratio values remains constant throughout the duration of the seismic excitation. This assumption is not fully applicable to a case when loose saturated soil profile undergo heavy shaking (PGA > 0.3 g). In this study, all simulations with input motion PGA >0.3 g have been performed by using the EL method instead of the NL method considering that cohesive soils (clay and silt) at Montreal sites are stiff and cohesionless soils (sand and gravel) are considerably dense. In addition, the field and laboratory data required to perform NL analyses are not currently available and may be investigated in future works.

Probabilistic Seismic Hazard Assessment (PSHA) was carried out for the administrative region of Attica (Greece). Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) values were calculated for return periods of 475 and 950 years for five sub-areas covering the entire region. PGA hazard curves and Uniform Hazard Spectra (UHS) in terms of spectral acceleration (Sa) values were generated for Athens, Methana, and the capitals of each island of Attica (Salamina, Aegina, Poros, Hydra, Spetses, Kythira, and Antikythira). Area sources were adopted from the Euro-Mediterranean Seismic Hazard Model 2013 (ESHM13) and its update, ESHM20, taking into account both crustal and slab tectonic environments. Ground Motion Prediction Equations (GMPEs) proposed for the Greek territory were ranked for PGA and PGV. Each GMPE was reconstructed as a weighted model, accounting for normal and non-normal focal mechanisms for each area source. PGA, PGV, and Sa values were computed using a logic tree, integrating the seismotectonic models as major branches and sub-logic trees, comprised of multiple ranked GMPEs for each area source, as minor branches. The results showed higher seismic hazard values in sub-areas near the Gulf of Corinth and the slab interface, which could indicate a need to revise the active building code in Attica.

Earthquake response spectral ordinates vary significantly with changes in orientation within the horizontal plane. This variation is characterized probabilistically in this study using a large database of recorded earthquake ground motions. For each ground motion record, response spectral ordinates are computed in all horizontal orientations as a function of the rotation angle with respect to the azimuth of maximum response and then normalized by (1) the maximum and (2) the median spectral ordinate from all these orientations. Nonlinear regression models are then fitted to the means, standard deviations, and correlations of both ratios, as a function of rotation angle. To achieve a more complete probabilistic description, probability distributions are fitted to both ratios at each rotation angle. These results can be used for several probabilistic seismic hazard computations, such as the sampling of response spectral ordinates at specific orientations within the same site. [ABSTRACT FROM AUTHOR]

The paper investigates the potential of adopting the spectral acceleration Sa(T) as an efficient measure for the estimation of the seismic performance of bare and infilled R/C buildings within the context of Performance-Based Earthquake Engineering. A large number of planar R/C buildings with different masonry infills' distributions are analyzed using nonlinear time-history analyses. The correlation between several damage measures and the Sa(T) for a wide range of periods is investigated. The results point out the conditions under which the Sa(T) can be used as an efficient parameter that describes adequately the damage response of bare and infilled R/C frames. [ABSTRACT FROM AUTHOR]

Two possible scenarios of strong earthquakes located about 30 km south of the city of Santiago de Cuba are presented in terms of peak ground acceleration (PGA) and spectral acceleration (PSA). Acceleration values are calculated for most of the municipalities in the eastern region and for various points in the city of Santiago de Cuba. Two earthquakes of magnitudes 7.0 and 7.3 respectively were modeled with an epicenter in the Oriente fault zone. Several parameters necessary in the calculations were investigated such as the stress drop and the attenuation function of the seismic waves. The results indicate significant rock accelerations in the municipalities of Santiago de Cuba and Guama with values that exceed 180 cm/s2. A shake map is also obtained for the city of Santiago de Cuba considering the spectral amplification of the ground. The maximum spectral acceleration values for periods of 0.3 seconds reach 480 cm/s2. [ABSTRACT FROM AUTHOR]