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The portal section of mountain tunnels usually suffers severe damage during earthquakes. The purpose of this paper is to investigate the seismic performance of the combined system of anchor rod and isolation layer in the portal section of the mountain tunnel. The numerical model was established based on the actual terrain of the engineering site and included the tunnel pillar portal structure, horizontal seismic wave input, and absorbing boundary conditions. Four cases were considered: without measures, anchor rod, isolation layer, and combination of anchor rod and isolation layer. Comparative analysis of the dynamic response and seismic performance of the structure under seismic action for each case. The results show that: (1) The combination measures reducing the maximum peak acceleration of the tunnel pillar portal and lining to 0.33g and 0.36g, respectively, achieving acceleration reduction rates of 30% and 36.8%; (2) The combination measures increases frictional resistance through anchor rod, providing restraint and support to the surrounding rock, and the isolation layer further mitigates the interaction between the surrounding rock and the lining, reducing the stress on the lining. This synergy reduces the maximum relative displacement of the tunnel portal pillar by 43.7% to 9.4mm, and the lining by 58% to 7.8mm; (3) The combination measures reduce the maximum peak principal stress of the lining to 1.48MPa, achieving a stress reduction rate of 68.23%. Effectively enhancing the seismic performance of the tunnel and reducing damage and failure. [ABSTRACT FROM AUTHOR]

In post‐earthquake damage assessment studies of reinforced concrete (RC) buildings, the most important consideration is to determine the damage and severity of structural elements is the determination of the damage and severity of structural elements. For earthquake damage to structural elements, such as columns and shear walls, decisions can be made about strengthening or demolition. However, due to the need for rapid assessment of damaged buildings after earthquakes, these two damage mechanisms can sometimes be confused. Non‐structural damage is classified as structural, leading to uneconomic structural decisions such as demolition or strengthening, or conversely, life safety issues arise from misidentifying critical structural damage with non‐structural damage. In this study, an artificial intelligence‐based damage assessment algorithm has been developed to accurately and quickly differentiate between structural and non‐structural damage. For the damage classification model, a deep learning algorithm was developed using the 9680 damage images obtained from field studies after the recent earthquakes of Mw ≥ 5; Istanbul‐Silivri (Mw: 5.8), Elazığ‐Sivrice (Mw: 6.8) and Izmir‐Seferihisar (Mw: 6.6) in Turkey. With an accuracy rate between 93% and 96%, the models constructed by selecting the optimal values correctly detected and categorised structural and non‐structural element damages in RC structures. The method developed in this study can help experts in damage assessment studies as a decision support mechanism. [ABSTRACT FROM AUTHOR]

This paper introduces machine learning-based Turkiye-specific ground motion models for the geometric mean horizontal component of peak ground velocity (PGV). PGV is a significant intensity metric to measure and diagnose potential earthquake damage in structures. Reliable prediction of PGV is of essential importance in precise calculations of seismic hazard. The efficiencies, reliabilities, and capabilities of various machine learning algorithms, including Random Forest, Support Vector Machine, Linear Regression, Artificial Neural Network, Gradient Boosting, and Bayesian Ridge Regression, are evaluated and compared. The most recently compiled Turkish strong motion database, which consists of over 950 earthquakes occurring from 1983 to 2023, is used for shaping the models' ability to learn and make accurate predictions. Three feature selection methods- Least Absolute Shrinkage and Selection Operator, Recursive Feature Elimination, and Pearson's Correlation- representing embedded, wrapper, and filter approaches, respectively, are applied to determine the most suitable estimator parameters to predict PGV. Residual analyses and statistical evaluation metrics are employed to measure the performance and effectiveness of the machine learning models. Among the algorithms applied, Gradient Boosting demonstrates exceptional success in predicting PGV, particularly when utilizing all estimator parameters (features) collectively. The Gradient Boosting model exhibits superior predictive capabilities compared to existing ground motion models. It is applicable to shallow crustal strike-slip and normal faulting earthquakes with moment magnitude ranging from 3.5 to 7.8 and Joyner and Boore distance up to 200 km. [ABSTRACT FROM AUTHOR]

Assessing the potential damage caused by earthquakes is crucial for a community's emergency response. In this study, four machine learning (ML) methods—random forest, extremely randomized trees, AdaBoost (AB), and gradient boosting (GB)—were employed to develop prediction models for the damage potential of the mainshock (DIMS) and mainshock–aftershock sequences (DIMA). Building structures were modeled using eight single-degree-of-freedom (SDOF) systems with different hysteretic rules. A set of 662 recorded mainshock-aftershock (MS-AS) ground motions was selected from the PEER database. Seven intensity measures (IMs) were chosen to represent the characteristics of the mainshock and aftershock. The results revealed that the selected ML methods can well predict the structural damage potential of the SDOF systems, except for the AB method. The GB model exhibited the best performance, making it the recommended choice for predicting DIMS and DIMA among the four ML models. Additionally, the impact of input variables in the prediction was investigated using the shapley additive explanations (SHAP) method. The high-correlation variables were sensitive to the structural period (T). At T=1.0 s, the mainshock peak ground velocity (PGVM) and aftershock peak ground displacement (PGDA) significantly influenced the prediction of DIMA. When T increased to 5.0 s, the primary high-correlation factor of the mainshock IMs changed from PGVM to the mainshock peak ground displacement (PGDM); however, the high-correlation variable of the aftershock IMs remained PGDA. The high-correlation factors for DIMS showed trends similar to those of DIMA. Finally, a table summarizing the first and second high-correlation variables for predicting DIMS and DIMA were provided, offering a valuable reference for parameter selection in seismic damage prediction for mainshock–aftershock sequences. [ABSTRACT FROM AUTHOR]

In February 2023, two catastrophic earthquakes in Turkey resulted in over 50,000 fatalities and over 300,000 injuries. This study investigated the psychological effects on firefighters who engage in rescue operations following these earthquakes, focusing on trauma-related symptoms, depression, anxiety, stress, and resilience. The research employed validated psychometric instruments, including the Post-earthquake Trauma Level Determination Scale (PETLDS); Depression, Anxiety, Stress Scale-21 (DASS-21); PTSD Checklist for DSM-5 (PCL-5); and Brief Resilience Scale (BRS), to assess the psychological states of firefighters. The primary goal of this study was to evaluate the psychological impact of earthquakes on firefighters. Specific objectives include quantifying trauma levels; identifying the prevalence of post-traumatic stress disorder (PTSD), depression, anxiety, and stress among firefighters; and investigating the role of psychological resilience in mitigating the effects of disaster-related psychological trauma. This study is also aimed at providing empirical evidence to inform the development of psychological support and intervention strategies for firefighters in the aftermath of these earthquakes. In this study of 223 primarily male firefighters, significant psychological impacts from earthquake trauma were observed. The PETLDS scores indicated high trauma levels in 28 participants and modest levels in 195. Subscales revealed affective responses and cognitive structure were most affected. DASS-21 scores showed higher depression, anxiety, and stress in the high trauma group. PCL-5 and BRS analyses confirmed higher PTSD symptoms and lower resilience in high-trauma individuals. Correlation analysis highlighted strong associations between trauma, psychological distress, and decreased resilience. These findings highlight the necessity for targeted mental health interventions and support mechanisms for firefighters, contribute to the establishment of training programs to enhance psychological resilience among firefighters, and add valuable insights to the field of disaster psychology. [ABSTRACT FROM AUTHOR]

This study quantifies the effects of long-duration earthquakes on the behavior of reinforced concrete (RC) buildings subjected to successive earthquake-tsunamis through the development of fragility surfaces. The suite is comprised of both ductile and nonductile systems, representing a portfolio of RC structures that could be found in a (coastal) community. Previous research has shown that long-duration earthquakes can significantly influence the structural responses and even the collapse behavior of building systems. Earthquakes with large moment magnitudes that produce tsunamis are often long duration events, yet ground motion duration has not been fully considered when generating tsunami fragility curves or successive earthquake-tsunami fragility surfaces. This study incorporates earthquake loading through a nonlinear time history analysis (NLTHA) and subsequent tsunami loading with a nonlinear static procedure. Detailed probabilistic structural models are subjected to both long-duration and regular-duration earthquakes through the NLTHA phase of the successive simulation to explore the possible impact of long-duration earthquakes on earthquake-tsunami fragility surfaces used to represent the behavior of these RC buildings. Results show that failure probabilities from the fragility surfaces are increased by up to 40% in some cases, with low- to mid-rise RC structures (ductile and nonductile; up to 8 stories) being adversely affected by long-duration earthquakes. Furthermore, this study reports the governing parameters of scalar and vector-valued fragility functions in the proposed RC portfolio exposed to long-duration earthquakes and tsunami hazards. These fragility surfaces can be useful in developing community-level models in risk-based or resilience-based decision-support for disaster mitigation. [ABSTRACT FROM AUTHOR]

This present research conducted an experimental study on the influence of different earthquake damages on the seismic performances of aged reinforced concrete (RC) beam-column joints retrofitted with basalt fiber-reinforced polymer (BFRP) sheets under cyclic loadings. Six beam-column joints included one benchmark specimen, one uncorroded specimen retrofitted with BFRP sheets, and four earthquake-damaged corroded specimens with the corrosion rates of 0% and 9% retrofitted with BFRP sheets. Test results demonstrated that the seismic performances of earthquake-damaged corroded specimens effectually improved after retrofitting with BFRP sheets, and the retrofitting effectiveness was significantly affected by the earthquake-damaged levels. The bucking of stirrups, spalling and crushing of concrete of retrofitted specimens were effectually postponed, while the ductility of corroded and uncorroded specimens under the earthquake damages increased after retrofitting with BFRP sheets. The total cumulative energy dissipation and final stiffness of retrofitted specimens considerably improved with the maximum increase of 22.3% and 14.3% comparing to those of benchmark specimen, respectively. Besides, the models for predicting the shear strength of RC beam-column joint cores considering the influences of earthquake damage, reinforcement corrosion, and FRP retrofitting were proposed. [ABSTRACT FROM AUTHOR]

To evaluate the seismic performance of aeolian sand concrete shear walls with hidden bracings, a total of 6 specimens were designed and constructed. These specimens were subjected to low cyclic load experiments while maintaining a constant axial compression ratio to assess the impact of the hidden bracings installation on the seismic performance of these walls. The findings reveal that the failure patterns of the shear walls, both with and without hidden bracings, are comparable. The formation and development of plastic hinges were observed at the wall's base, which result in significant structural failure. The aeolian sand concrete shear walls with hidden bracings have superior load-bearing capacities when compared to their conventional counterparts under same lateral displacements. The hysteresis curves obtained from all 6 specimens are relatively complete and display an evident pinching effect. The aeolian sand concrete shear walls equipped with hidden bracings demonstrate enhanced seismic energy dissipation and ductility relative to the ordinary ones. After analysis and comparison, it is determined that a cumulative damage analysis model, based on repeated energy loads of concrete structures, aligns well with test results. This model proves to be an effective tool for evaluating the damage performance of aeolian sand concrete shear walls with hidden bracings. [ABSTRACT FROM AUTHOR]

Earthquakes pose a significant threat to life and property worldwide. Rapid and accurate assessment of earthquake damage is crucial for effective disaster response efforts. This study investigates the feasibility of employing deep learning models for damage detection using drone imagery. We explore the adaptation of models like VGG16 for object detection through transfer learning and compare their performance to established object detection architectures like YOLOv8 (You Only Look Once) and Detectron2. Our evaluation, based on various metrics including mAP, mAP50, and recall, demonstrates the superior performance of YOLOv8 in detecting damaged buildings within drone imagery, particularly for cases with moderate bounding box overlap. This finding suggests its potential suitability for real-world applications due to the balance between accuracy and efficiency. Furthermore, to enhance real-world feasibility, we explore two strategies for enabling the simultaneous operation of multiple deep learning models for video processing: frame splitting and threading. In addition, we optimize model size and computational complexity to facilitate real-time processing on resource-constrained platforms, such as drones. This work contributes to the field of earthquake damage detection by (1) demonstrating the effectiveness of deep learning models, including adapted architectures, for damage detection from drone imagery, (2) highlighting the importance of evaluation metrics like mAP50 for tasks with moderate bounding box overlap requirements, and (3) proposing methods for ensemble model processing and model optimization to enhance real-world feasibility. The potential for real-time damage assessment using drone-based deep learning models offers significant advantages for disaster response by enabling rapid information gathering to support resource allocation, rescue efforts, and recovery operations in the aftermath of earthquakes. [ABSTRACT FROM AUTHOR]

On 26th May 2021, an earthquake with a moment magnitude Mw 5.1 hit the densely populated cities of Gisenyi (Rwanda) and Goma (D.R. Congo) which sit on the active East African Rift System. It was one of the largest earthquakes associated with the 2021 Mount Nyiragongo eruption. Although of moderate magnitude, the earthquake substantially damaged manmade structures. This paper presents field observations on the geotechnical impact, building damage, and factors contributing to the heightened destruction caused by this moderate earthquake. The damage pattern observed in the field indicates that masonry structures with inadequate seismic detailing were the most damaged buildings. In addition, the statistical analysis of the damaged buildings indicates most of the damaged structures were located in plains covered by volcanic soil. The intensity of the waves was estimated using the building damage data based on the European Macroseismic Scale (EMS-98). An intensity distribution map was generated for the surveyed area, suggesting EMS-98 intensity of VIII or IX along the eastern basin boundary fault and VII around the cities of Goma and Gisenyi where the land is composed of black cotton soil of volcanic origin. The higher intensity values along the eastern basin-bounding fault indicate that a reevaluation of the seismic hazard for the region is necessary. Since this is the first-ever such damage survey for the region, the developed intensity map can be used to understand the correlation between the intensity of the ground motion and damage severity which contributed to the seismic hazard assessment of the study area. [ABSTRACT FROM AUTHOR]

Post-earthquake scientific investigation is considered as one of the pillars supporting earthquake engineering. On the 6th of February, 2023, two deadly strong earthquakes, which magnitudes were Mw7.8 and Mw7.5, respectively, shook Southern-Central Turkiye, caused significantly large casualties and tremendous economy loss. Through on-site field survey, liquefaction phenomena and liquefaction-induced damage to buildings were observed. The observations are: (1) the consequences of soil liquefaction included sandboils, lateral spreading, ground subsidence and ground failure caused by loss of bearing capacity; (2) in two liquefied areas, lateral spreading was investigated and the spreading displacement ranged from several centimeters to meters, resulting in damage or demolishing of buildings; (3) in Golbasi town, many 6 to 10-story buildings significantly subsided and tilted due to liquefaction-induced loss of ground bearing capacity. Buildings subsided by tens of centimeters to 2 ~ 3 m, and tilted by several degrees to tens of degrees; (4) ground subsidence of tens of centimeters with respect to adjacent buildings was detected. The liquefaction phenomena were compared with those triggered by the 2008 Wenchuan, China, earthquake which maintained similar in magnitude and focal depth. The findings and lessons learnt will enhance the understanding of liquefaction hazard, challenge the current liquefaction countermeasures, and eventually facilitate to improve liquefaction mitigation techniques. [ABSTRACT FROM AUTHOR]

Introduction: Buildings that collapse or are damaged by earthquakes are responsible for the majority of earthquake-related casualties. High-precision building data are the key to improving the accuracy of risk assessments of earthquake disaster loss. Many countries and regions have also proposed varying regional building exposure models, but most of these models are still based on administrative-level (city or county) statistical data; furthermore, they cannot accurately reflect the differences among buildings in different towns or villages. Methods: Although field investigation-based "township to township" methods can obtain more accurate building inventory data, considering costs and timeliness, remote sensing and other diverse data should be combined to acquire building data. Based on the field survey data of three cities in shanxi Province, combined with Global Human Settlement Layer (GHSL) data, this study is conducted on building inventory data. Data regarding the proportion of each building type and corresponding lethality level in each township are obtained based on the classification of building height, and the overall lethality level at the building level and township level is calculated on this basis. Results: The fitting results between the calculated results and the field survey results are good, the error is within 0.15, and the fitting R2 values of Xian, Baoji and Ankang are 0.6552, 0.5788 and 0.5937, respectively. Therefore, an earthquake disaster loss risk assessment is conducted based on the building level. Discussion: The findings indicate that the risk of casualties caused by the same building type can vary by city. Generally, the areas with high disaster loss risk in the three cities are distributed mainly in urban areas; the disaster loss risk in the newly built areas of each city is relatively low. According to the quantitative assessment results for each city, Xi'an has the highest loss risk, while Baoji and Ankang have the same loss risk. Based on the method constructed in this paper, we can realize the quantitative assessment of earthquake disaster loss risk at the building level to better target pre-earthquake emergency preparation and post-earthquake auxiliary decision-making. [ABSTRACT FROM AUTHOR]

Recently, Egypt had seismic activity. These seismic events have affected the stability of minarets, especially historical ones. Weight is one of the minaret's main stability factors. The main objective of the current research is to perform a three-dimensional (3D) assessment of an existing minaret, determine its accurate spatial model, document its current condition, examine its stability in the event of earthquakes, and identify the requisite measures to safeguard the minaret from any potential damage. The masonry to construct the minaret was used by extracting and examining specimens of this substance to determine its physical characteristics. The current work created three-dimensional models of the Abou-Ghanam El-Bialy minaret using a terrestrial laser scanner (TLS) to document its current condition, as well as minaret was subjected to a free vibration analysis using 3D finite element modeling. Finally, the minaret's seismic behavior was assessed utilizing mode forms, base responses, and normal stresses. The surveying method effectively documented the Minarets' existing case. The 3D seismic analysis showed that the minaret responded dynamically to earthquake loading, with mode shapes, base reactions, and normal stresses being crucial characteristics. Based on these data, we may suggest procedures to protect the minaret during seismic events. [ABSTRACT FROM AUTHOR]

In the southern Sichuan Basin of China (SSBC), hydraulic fracturing (HF) production of shale gas and surface buildings have been seriously affected by some medium scale (local magnitude ML > 4.0) earthquake events. In this study, focusing on relocated hypocenters in SSBC from January 2016 to May 2017, the Density-Based Spatial Clustering of Applications with Noise algorithm was introduced to divide it into four seismic regions. The temporal evolution of seismicity parameters, detailed views of potential faults near injection wells and spatial migration of seismic activity in each region were obtained. Moreover, the statistical correlation between seismicity and engineering disturbance was calculated by adopting epidemic type aftershock sequence model (ETAS); the relationship between corner frequency, stress drop and seismic moment of each region were analyzed, and the spatial distribution of the stress drop, the relationship with the focal mechanism solutions (ML > 3.5) and the fault slip-tendency under the regional stress pattern were discussed. The results show that the seismic diffusion rate of each region can be well described by the square root envelope (0.3–0.8 m2/s) and seismicity has a strong cluster mode (triggered events) and a weak background mode (independent events). Most (more than 97.5%) of the stress drops are in the range of 0.1–10 MPa, and the high stress drops is mainly located in the YS108 shale block; under the current regional stress pattern, the faults in region YS108 are unfavorablely oriented, while those in the south of N201 are favorablely oriented, with a high sliding trend. This knowledge may provide time to take mitigating actions to reduce the potential for damaging earthquakes. Highlights: Spatial clustering in SSBC based on DBSCAN algorithm and the relocated hypocenters associated with hydraulic fracturing, and the spatiotemporal migration characteristics are analyzed. Focal mechanisms indicate different fault planes, matching well with relocated hypocenters Statistical relationship between source parameters (corner frequency, stress drop, seismic moment, etc.) and regional variations Discuss the slip-tendency of potential faults in various regions under inversion of current stress pattern [ABSTRACT FROM AUTHOR]

The Sichuan-Yunnan block is a tectonically active region in China, with frequent large earthquakes occurring in and around it. Despite most earthquakes being concentrated along boundary faults, intraplate faults also have the potential to generate damaging earthquakes. Remote sensing makes it possible to identify these potential earthquake source faults. During an active fault investigation in the Liangshan area, a distinct lithological boundary named Caimashui fault was found. The geometric distribution and kinematic parameter of the fault is crucial for assessing seismic hazards and understanding the deformation pattern within the Sichuan-Yunnan block. The Caimashui fault is mapped with remote sensing interpretation, a field survey, and UAV measurement. Through trenching and Quaternary dating, the Late Quaternary active characteristics of the fault are studied. The fault is a Holocene active dextral strike-slip fault with a reverse component, exhibiting a dextral strike-slip rate of ~0.70 ± 0.11 mm/a. Paleoseismic investigation shows that the last surface rupture event of the Caimashui fault occurred later than 4150 ± 30a BP, with a magnitude of M ≥ 7.0. The fault may act as a secondary splitting fault, absorbing the deformation caused by various sinistral strike-slip rates of the boundary faults and the potential energy from the counterclockwise rotation of the Central Yunnan micro-block. [ABSTRACT FROM AUTHOR]

In Almaty, the largest city in Kazakhstan lying on a high seismic region, many residential buildings constructed during the Soviet Union are still in service. These buildings were not properly designed against earthquakes and special seismic detailing was not well considered according to the local design code. Therefore, this paper presents an analytical seismic assessment of two typical reinforced concrete moment frame residential structures constructed in this era, representing 812 buildings with almost identical construction materials, geometries, and structural details. Two-dimensional nonlinear models were developed for these buildings in each orthogonal direction based on the structural details collected from a Kazakh government agency. Incremental dynamic analyses were then performed using 24 historical strong ground motions with fault characteristics similar to those in the Almaty region. Structural global and local seismic responses were investigated. A new approach was proposed to define structural global inter-story drift limits at different damage states based on local seismic demands considering uncertainties of earthquakes and structural nonlinear dynamic responses. Based on these inter-story drift limits, the structural fragility curves were then developed to identify the damage probability of these buildings, which were further used to roughly estimate repair costs at different earthquake intensity levels. It has been found that these buildings are vulnerable to destructive earthquakes due to poor structural details. They possess a high probability of incurring extensive damage (high repair cost) or even collapsing (irreparable) at the earthquake intensity level, with a return period of 475 years or 2475 years, respectively. [ABSTRACT FROM AUTHOR]

Recent geodetic and seismological observations of two major earthquakes in southeastern Türkiye in February 2023 have revealed complex rupture initiation, propagation, and segmentation along the East Anatolian Fault Zone (EAFZ) and surrounding regions. However, the role of upper crust structures along the EAFZ in determining the diverse rupture processes of this earthquake doublet remains unclear. To further investigate this, we employed double-difference location and seismic tomography techniques to determine high-resolution seismic velocities (VP, VS) and Poisson's ratio (σ) structures using a multi-parameter joint tomographic algorithm. Our dataset includes 100,833 high-quality source-receiver travel-time pairs of P- and S-waves. We find that the unique rupture processes of this earthquake doublet were primarily influenced by contrasting crustal seismic structures and localized geological settings. The Mw7.8 mainshock was initiated within a transitional edge zone characterized by a rigid part (asperity) of the seismogenic zone with sharp contrast variations in rock strength ranging from low to high along the EAFZ. In comparison, the Mw7.6 rupture originated in a ductile belt featuring fluid saturation with low-VP, low-VS, and high-σ values that extended parallel to the Çardak Fault. The pronounced contrast structures observed along the former rupture can be attributed to the oblique collision system between the weakened section of the east Anatolian plateau and the brittle Arabian platform, while the latter rupture was initiated within the ductile structure associated with fluid intrusion caused by the northward subduction of the Cyprus slab and subsequent detachment. Furthermore, the occurrence of the first earthquake (E1) serves to alleviate shear stress on the second earthquake (E2) fault, potentially impeding the initiation of an E2 rupture. On the contrary, this event also significantly reduces the normal stress acting on the E2 fault due to a double left-lateral strike-slip system within a triangular region. This reduction not only results in a decrease of fault friction force and an increase in rock porosity but also induces lower strain drops and the redistribution of Coulomb stress, thereby contributing to the initiation of the E2 event. The proposed rupture pattern exceeds the conventional model that governs individual earthquake ruptures, offering new insights for mitigating potential seismic disasters in Türkiye. The lessons learned from this doublet event can contribute to reevaluating the ongoing risk of damaging earthquakes in China's South-North Seismic Zone or other regions worldwide with comparable geological conditions. [ABSTRACT FROM AUTHOR]

Functional recovery is a new, nonstandardized building design objective, intended to improve a building's capacity to maintain or rapidly restore basic intended functions after a natural hazard event. Current building seismic design standards, which target life-safety performance objectives, provide limited requirements to ensure buildings maintain, or rapidly recover, function after earthquakes. Therefore, the expected functional recovery performance that is provided by current building codes is unclear. To provide clear and systematic insights to inform the development of prescriptive and performance-based design standards, this study documents the functional recovery performance for a set of 60 reinforced concrete archetype buildings. The results indicate that the estimated functional recovery time for reinforced concrete buildings designed to life-safety standards may approach 1 year, on average, for design-level earthquakes. Additionally, while increased strength and stiffness requirements significantly reduce the likelihood of a building being marked as unsafe due to structural damage, additional design provisions for nonstructural components are required to ensure a high confidence of rapid recovery. The findings from this study clarify the expected post-earthquake recovery of modern reinforced concrete buildings and identify key trends in underlying damage and response mechanisms required to improve future building performance. [ABSTRACT FROM AUTHOR]

In December 2023, a 6.2 magnitude earthquake struck Jishishan, Gansu Province. This study utilized the Real‐time Earthquake Damage Assessment using City‐scale Time‐history analysis (RED‐ACT) system to analyze the seismic damage caused by the event. The analysis included assessments of strong ground motion records, building damage, and human acceleration feeling. The results indicate the following: (1) The earthquake‐induced significant ground motion. The response spectrum at the 0–1.3 s period range is far above the 7° design‐based and maximum considered earthquake levels, and it also far exceeds the 9° maximum considered earthquake level. How to provide a more scientific and reasonable seismic design standard to ensure the anti‐collapse performance of buildings still requires further in‐depth research. (2) The RED‐ACT analysis results indicate that the destructive power of this earthquake was significant. The strong ground motions recorded near the epicenter could cause a certain number of buildings to collapse, with the collapsed buildings mainly being raw‐earth/wood structures and unreinforced masonry structures. The main damage states of buildings assessed correspond generally with the actual earthquake damage survey results. (3) The RED‐ACT system can provide assessment results of human feeling of acceleration at different locations, and the assessment results take into account the amplification effect of acceleration by different floors, which can provide a reference for post‐earthquake science popularization and for reducing post‐earthquake panic among the population. [ABSTRACT FROM AUTHOR]

The 1755 Lisbon earthquake holds significant historical importance in Portuguese history. The subsequent tsunami resulted in extensive destruction and damage, affecting not only Lisbon but also other regions of Portugal, Spain, and North Africa. This significant and hazardous event led to an increase in awareness about earthquake and tsunami risks, not only within Portugal but throughout Europe. This heightened awareness facilitated advancements in scientific developments, including design codes, standards, and earthquake engineering. However, recent studies focusing on hazard assessment for Lisbon are limited. For this reason, this paper aims to present a comprehensive probabilistic seismic hazard analysis (PSHA) for the Lisbon metropolitan area. The first stage of PSHA involves defining applicable and active seismic source models (area and line sources) within the study area. Subsequently, historical and instrumental earthquake records are collected to build a homogenized earthquake catalog, utilizing both global and local earthquake databases. Following this, the completeness level of the earthquake catalog is tested. By incorporating suitable ground motion models to the region and local soil characteristics, seismic hazard maps for various return periods and hazard curves in terms of peak ground acceleration (PGA) are developed. The findings based on the area source model agree with existing literature, indicating PGA values ranging from 0.3 g to 0.9 g, 0.2 g to 0.7 g, 0.2 g to 0.5 g, and 0.1 g to 0.3 g for return periods of 2475, 975, 475, and 50 years, respectively. [ABSTRACT FROM AUTHOR]

Huge losses of life and property occurred as a result of two independent catastrophic earthquakes on 6 February 2023 in the Eastern Anatolian Fault Zone, where no significant earthquake has occurred in approximately 500 years. The earthquakes, whose epicenters were in the Pazarcık and Elbistan districts of Kahramanmaraş province at 9 h intervals, had magnitudes of Mw = 7.7 and Mw = 7.6 and caused different levels of structural damage, especially in masonry-style structures in rural areas. In this study, the damage that occurred in masonry village schools, especially in rural areas, during these two earthquakes was evaluated in terms of the characteristics of the earthquake and within the scope of civil engineering, and the causes of the damage were discussed. The damage levels of the masonry schools examined were classified using the European Macroseismic Scale (EMS-98). Information about the Kahramanmaraş earthquakes was given and structural analyses were carried out for a widely used reference school building. The school building block was analytically modeled, and its seismic load-bearing capacities were predicted through pushover analysis in TREMURI software. The study also includes repair and strengthening recommendations for such structures. [ABSTRACT FROM AUTHOR]

Recent seismic events have prompted research into innovative and sustainable materials for strengthening and repairing obsolete and vulnerable buildings. These earthquakes have exposed the high seismic vulnerability of existing reinforced concrete (RC) buildings, particularly in secondary structural elements like infill walls. In addition to structural issues, these buildings often face significant energy deficiencies, such as thermal bridges, due to inadequate insulation. Traditionally, structural and energy improvements for residential buildings are addressed separately with different methods and protocols. This preliminary study is part of a broader research initiative at the University of Reggio Calabria (Italy), aiming to design an innovative fiber-reinforced plaster using natural, sustainable, and locally produced materials to enhance the energy and structural performance of existing wall infills. The study investigates two plaster matrices made of natural hydraulic lime and silica sand, with 15% and 30% cork granules added. Mechanical and thermophysical tests on multiple specimens were conducted to evaluate their suitability for seismic and energy retrofitting of infill walls. Results indicate that adding cork reduces mechanical strength by approximately 42% at a 30% cork content without compromising its use in seismic retrofitting. Thermophysical tests show improved thermal performance with a higher cork content. These findings suggest that the lime–cork mixture at 30% is effective, offering excellent ductility and serving as a promising alternative to traditional cementitious plaster systems. The next experimental phase will test matrices with varying percentages of gorse fiber. [ABSTRACT FROM AUTHOR]

Earthquake is one of the main factors causing structural disasters in current buildings. Under earthquake action, adjacent building structures are generally in different vibration stages, and collisions may occur in the structures, which may cause serious damage to the structure. In order to prevent certain earthquakes from damaging the designed buildings, this article mainly introduced the design and analysis of a numerical algorithm for seismic nonlinear structural dynamic response based on the HVSR algorithm. This article evenly divided the acceleration response time series into 15 time periods and then selected the position corresponding to the peak point of instantaneous amplitude within each period as the selected data point position. The same seismic load can be applied at the bottom of the established nonlinear model to extract the dynamic response data of the top layer of the structure, and then, the instantaneous amplitude and corresponding instantaneous phases and frequencies of the main components of the structural dynamic response can be extracted through the time-varying filter and Hilbert transform based on the discrete analytic mode decomposition. Under the influence of these four ground motions, the collision force within the range of 0–50 kN accounted for over 87% of the total number of collisions. In the comparison results of collision response to peak displacement, the four ground motions all led to structural collision, and the collision inhibited the positive peak displacement response of node 1512. Compared with noncollision, the peak displacement was reduced by 27.273, 33.675, 27.727, and 37.248%, respectively. The peak displacement of 1512 nodes was suppressed and reduced by 18.856%. The results indicate that the HVSR algorithm can obtain the instantaneous characteristic parameters of nonlinear structural dynamic response and achieve model correction. [ABSTRACT FROM AUTHOR]

Calibrating parametric fragility curves via empirical damage data is one of the standard approaches to derive seismic structural vulnerability models. Fragilities based on empirical data require the characterization of the ground motion (GM) intensity at the building sites in the area affected by the earthquake producing the observed damages. This is commonly conducted via ShakeMap, that is, a map of the expected values of a Gaussian random field (GRF) of the logarithms of a GM intensity measure conditional to magnitude, location, and possibly a set of recordings of the earthquake. Once that intensity and damage data at the same sites are available, the typical approach calibrates a two‐parameter fragility model. However, ShakeMap estimates are affected by uncertainty deriving from that of the GM model used to characterize it. Furthermore, such an uncertainty can be reduced by building damage data, which provide information on the shaking intensity at the sites where damage is observed. It is shown herein that if this uncertainty is not addressed, also considering the shaking information provided by damage, the estimates of the fragility parameters obtained using a median ShakeMap only can be biased, and a recommended maximum likelihood estimation procedure – which exploits the expectation maximization algorithm – is provided. These arguments are illustrated via an application considering damage data from the 2009 L'Aquila earthquake in central Italy. [ABSTRACT FROM AUTHOR]

To better aid the quick and accurate assessment of economic loss after the occurrence of future damaging earthquakes, we develop a grid-level fixed asset model for China covering the period from 1951 to 2020. The modelling process can be divided into two stages: (1) the compilation of provincial-level fixed asset data series using the perpetual inventory method (PIM) and fixed assets-related statistics; (2) the disaggregation of provincial-level fixed assets into grid-level (1 km × 1 km resolution) using different combinations of remote sensing ancillary data (i.e., nighttime light, built-up surface area, population) for different periods, considering their temporal availability. As of 2020, the total estimated value of fixed assets in China reaches 589.31 trillion Chinese yuan (in the 2020 price level). Consistency checks have been performed by comparing our modelled fixed assets with those from other studies and data sources at different administrative levels, and good consistency has been achieved. The modelled grid-level fixed asset maps from 1951 to 2020 will be publicly accessible and can be conveniently extended to more recent years as new statistics on fixed assets become available in the future. [ABSTRACT FROM AUTHOR]

Depending on the characteristics of the existing buildings, earthquakes can cause damage at different levels and have a significant impact on the environment. The structural damages after the earthquakes have shown the importance of analysing both the existing and the damaged buildings. In this study, the Turkish rapid seismic assessment method, which was used for the existing building stock before a possible earthquake, was applied to the damaged reinforced concrete (RC) buildings after the 6 February earthquakes in Kahramanmaraş (Türkiye). The building data were used as a result of field observations in the provinces of Adıyaman, Hatay, and Kahramanmaraş, where the greatest destruction was caused by these earthquakes. Five RC buildings from each province were considered. The rapid assessment method was applied to a total of 15 buildings with different levels of damage. For this purpose, pre-earthquake images of the buildings were obtained, and an earthquake performance score was obtained for each building, taking into account the sustained damage during the earthquake. The primary aim of this study is to show the effects of structural irregularities on earthquake behaviour and to demonstrate the applicability of the rapid assessment methods used before the earthquake. The results obtained clearly demonstrate the effectiveness of rapid evaluation methods for existing building stock. Structural analyses were also carried out in this study to address the fact that the height of the ground storey is higher than the other storeys, which is one of the factors leading to a soft storey. [ABSTRACT FROM AUTHOR]

The buildings in various geographical conditions are strengthened due to different reasons, such as earthquakes, fire, or deterioration. One of the important issues is that comfort levels are ensured, and energy consumption is kept at a minimum in educational buildings where renovation and strengthening work is being carried out. In this study, in terms of energy consumption and acoustic comfort, a method is proposed to examine a building damaged in an earthquake and then strengthened. The method has also been created and implemented to provide control and improvement suggestions in terms of thermal and acoustic conditions in strengthening projects of buildings. As a case study, the pre- and post-reinforcement situation of an educational building in a temperate humid climate has been evaluated. In addition, different glazing scenarios that reduce energy consumption while increasing facade noise reduction have been developed and analyzed. The results showed that while sufficient noise reduction is achieved in the building envelope, there is a 15.9% reduction in the total energy consumption of the building. The optimum scenario decreased total energy consumption by 19.4 % in B113 and 26 % in B114 and increased the facade noise reduction levels by 14.2 dB in B113 and 15 dB in B114. The proposed method and the findings will contribute to the design process of newly designed, renovated, and strengthened buildings in terms of energy efficiency and indoor acoustical comfort. [ABSTRACT FROM AUTHOR]

In Japan, a country prone to earthquakes, numerous damaging earthquakes have been recorded throughout history, often accompanied by descriptions of mysterious earthquake lights (EQL), which may involve various mechanisms. In this article, the possible mechanisms for different types of EQL in 11 cases are reviewed among 21 selected earthquakes. These involve preseismic physicochemical variations in the geological structure of the fault in the lithosphere, which contains deep Earth gases such as radon, methane, and others, as a primary factor for EQL generation. Additionally, various seismic, atmospheric, hydrospheric, and ionospheric variations interact with each other, resulting in the visualization of characteristic anomalous phenomena, such as glowing or shining ground, mountains, offshore areas, and skies of various colors. These phenomena appear momentarily but can sometimes last for extended periods. Because EQL often appear just before an earthquake, their study might be significant for earthquake prediction. Additionally, EQL involving methane flames in the ground is an important research topic as it relates to public safety. Was what they witnessed paranormal? [ABSTRACT FROM AUTHOR]

Earthquakes have serious destructive effects on building structures, and effective seismic design is the key to building design. In order to reduce the damage of earthquakes to building structures, seismic design of buildings is based on improved viscous dampers. First, the displacement seismic design was studied and a displacement-based structural seismic model was constructed. In addition, analyzing traditional viscous dampers, an improved viscous damper is adopted based on it. Through equivalent damping expression, a displacement seismic model based on the improved viscous damper is constructed. Finally, two targets, frequent and rare earthquakes, were selected for experimental analysis. In frequent earthquake experiments, the improved viscous damper structure increased the shock absorption rate by 35.65 % compared to the no-structure design. In the shear force comparison, the maximum shear force of the improved viscous damper structure in the HB wave X direction is 2186 KN, which is the smallest shear force among the three structural designs. In a rare earthquake experiment, the maximum value of the floor shear force in the X-direction of the Humbolt bay wave of the proposed improved viscous damper structure was 8696 KN. Compared with other structures, the floor shear force was the smallest. In the comparison of floor displacements, the maximum inter-story displacement in the Humbolt bay wave Y-direction of the proposed improved viscous damper structure is 162 mm, which is the smallest inter-story displacement compared with other structures. In addition, the structure apex displacement was also compared. The structure apex displacement value of the improved viscous damper structure was lower than that of other structures and was in the slight damage range. The overall seismic effect was significantly better than other structural designs. The research content is conducive to optimizing the application effect of viscous dampers and provides technical reference for the seismic design of building structures. [ABSTRACT FROM AUTHOR]

Zhuanyao dwellings faced significant seismic risks in rural regions of China. Therefore, a shaking-table test was performed to explore the seismic performance of Zhuanyaos and validate the finite-element simulation results. The results showed that the damage to the pier and roof levels of Zhuanyaos was more severe after earthquakes, resulting in a noteworthy increase in the displacement responses of these two levels compared to that of the vault level. The damage to the front structure (Yaolian) and mid-pier of the Zhuanyao were more severe than the damage to the back wall and side pier, respectively, which caused a significant reduction in acceleration responses of Yaolian and mid-pier. Following the crack development, dynamic response, and field investigation, three typical collapse modes of Zhuanyaos were presented. Subsequently, the parametric analysis was conducted using a verified finite-element simulation method. The results show that using the catenary arch can reduce earthquake damage in Zhuanyaos. Increasing the width of the middle pier can improve the seismic performance of Zhuanyaos to a certain extent; however, it may exacerbate local damage to the structure. Besides, the high seismic vulnerability of Zhuanyaos stemming from an increasing thickness of overlying soil cannot be ignored. [ABSTRACT FROM AUTHOR]

When traversing through an active strike-slip fault, buried pipelines may be subjected to permanent ground deformation (PGD), causing large strains in the pipeline during an earthquake. The presence of bends near the fault-crossing zones may further increase the strain in the pipe. Moreover, it is well acknowledged that bends are the most vulnerable location to earthquake damage, mainly when compressive strain develops due to PGD. Hence, most design guidelines recommend constructing pipelines without field bends, elbows, and flanges crossing the fault zone. However, it is not always possible to provide only a straight segment of the pipeline, especially for blind faults where the location of the faults is unknown. Hence, the present study aims to investigate the response of buried continuous steel pipelines with field bends subjected to strike-slip faulting by conducting an extensive parametric study. A three-dimensional pipe-soil interaction model is developed in a finite element framework for this study. The pipeline response in terms of its maximum von-Mises stress and maximum longitudinal stress and strain due to fault crossing is studied for various influencing parameters such as pipe bend angle, soil strength, pipe burial depth, and distance of the fault trace from the bend. Based on the results obtained, suitable relationships in terms of modification factors over the response of a straight pipeline as a function of a few critical parameters are determined using regression analyses. It is concluded that providing bends to the pipeline can significantly affect its structural response when subjected to fault displacement when the fault trace is close to the pipe bend. The primary outcome of this investigation would be to suggest a simplified methodology to estimate the response of pipelines having field bends while crossing fault lines from the response of straight pipelines in a similar scenario. [ABSTRACT FROM AUTHOR]

This article reports on the findings of an investigation on 29 historic stone masonry buildings located in the cities of Hatay and Osmaniye following the 2023 Turkey earthquake sequence. The earthquake couplet on 6 February (with moment magnitudes 7.8 and 7.5) and the following events (including another earthquake which occurred on 20 February with a moment magnitude of 6.3) resulted in significant damage to the buildings. To understand why, the examined buildings were assigned an EMS-98 damage level (ranging from 1 to 5) and descriptive response categories (masonry disaggregation, local mechanism, and global response). Overall damage statistics indicated that masonry disaggregation was common and coterminous with local mechanism response. Wall geometry and construction quality indices were then investigated to explore why these were the dominant damage mechanisms. Wall geometry indices highlighted insufficient amount of walls to resist the local seismic demands, particularly in the transverse (e.g. short) direction of buildings. This deficit promoted the formation of local mechanisms. Construction quality indices suggested that stone layouts did not enable interlocking and that the walls were prone to disaggregation. To further investigate the role of material properties on the observed damage, materials were characterized using three non-destructive testing techniques: ultrasonic pulse velocity (UPV) measurements to estimate the static elastic modulus of stones, Schmidt rebound hammer (SRH) tests to estimate the compressive strength of stones, and the mortar penetrometer (MP) tests to estimate the compressive strength of mortar. The measurements indicated poor mortar quality, which may have expedited failures. Using established correlations, various other important material parameters (e.g. mortar cohesion and homogenized masonry strength) are derived. It is envisioned that the damage observations and the material measurements in this article will inform detailed modeling efforts on the behavior of historic masonry buildings during the earthquakes. [ABSTRACT FROM AUTHOR]

We conducted large-depth Ground-Penetrating Radar investigations of the seismogenic Casamicciola fault system at the volcanic island of Ischia, with the aim of constraining the source characteristics of this active and capable fault system. On 21 August 2017, a shallow (hypocentral depth of 1.2 km), moderate (Md = 4.0) earthquake hit the island, causing severe damage and two fatalities. This was the first damaging earthquake recorded on the volcanic island of Ischia from the beginning of the instrumental era. Our survey was performed using the Loza low-frequency (15–25 MHz) GPR system calibrated by TDEM results. The data highlighted variations in the electromagnetic signal due to the presence of contacts, i.e., faults down to a depth larger than 100 m below the surface. These signal variations match with the position of the synthetic and antithetic active fault system bordering the Casamicciola Holocene graben. Our study highlights the importance of employing large-depth Ground-Penetrating Radar geophysical techniques for investigating active fault systems not only in their shallower parts, but also down to a few hundred meters' depth, providing a contribution to the knowledge of seismic hazard studies on the island of Ischia and elsewhere. [ABSTRACT FROM AUTHOR]

This study is focused on an evaluation of the correlation between the soil conditions and the seismic damage observed after the Vrancea March 4, 1977 intermediate-depth earthquake in Craiova, Romania. A significant number of existing studies in the literature have focused on the evaluation of damage for Bucharest, but the effects of the 1977 earthquake in Craiova have been very rarely discussed and presented. Craiova was the second city in Romania after Bucharest in terms of building damage and casualties as a result of the 1977 Vrancea seismic event, even though it is situated at a considerable distance (more than 250 km) from the epicenter. The 1977 event affected old low-rise masonry structures located in the central part of the city, as well as low-rise unreinforced masonry structures built after 1950. The soil conditions are evaluated based on a recently compiled collection of geological, geotechnical, and ground motion data from the study area. No correlation between the earthquake observed damage andthe number of standard penetration test (SPT) blows at a depth of 6 m or the soil layer at a depth of 3 m can be inferred from the available data. Moreover, the analyses show practically no influence of the terrain slope on the ground motion amplitudes for Craiova, which is situated on the left bank of Jiu River. The vulnerability characteristics of unreinforced masonry structures from Craiova and other cities are also evaluated in this study. The relative frequencies of unreinforced masonry structures having increased damage degrees is significantly larger for the Iasi and Craiova data sets. Finally, an estimation of the peak ground accelerations in four cities in Romania is evaluated based on the damage of unreinforced masonry structures. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the seismic performance of reinforced concrete shear walls in in‐plane and out‐of‐plane directions under single main shock and mainshock‐aftershock sequences. Two shear wall specimens were designed for low cycle load tests to withstand in‐plane, in‐plane then out‐of‐plane (IP‐OP), out‐plane, and out‐of‐plane then in‐plane (OP‐IP) forces, respectively. The seismic performance of shear walls under different forces was assessed by analyzing macroscopic failure phenomena and the novel performance parameters of specimens, following which their damage status was evaluated. The specimens were simulated using finite element software, and two frame shear wall structural systems were designed so that non‐linear time history analysis could be performed to assess the deformation and damage to the shear walls in the two directions of the plane under a single main impact and different input directions of mainshock‐aftershock sequences. The results revealed that following damage in the in‐plane direction of the shear wall, seismic capacity decreased significantly if it was subjected to a force in the out‐of‐plane direction once again, and the degree of damage under the earthquake action of mainshock‐aftershock sequences was significantly higher than that under the single main shock action. Therefore, it is necessary to pay special attention to the seismic performance of the out‐of‐plane direction of the shear walls and examine the seismic performance of the structural system under different input directions of mainshock‐aftershock sequences. [ABSTRACT FROM AUTHOR]

Strong earthquake disasters can cause noticeable damage correlations among regional buildings with similar mechanical properties, termed structure‐to‐structure seismic damage correlation, which has a pronounced impact on the regional seismic risk assessment and therefore needs to be properly quantified. This study first introduces a time‐domain analytical and equivalent frequency‐domain analysis based on random vibration theory for calculating structure‐to‐structure seismic damage correlation coefficients. Subsequently, by employing the spatially consistent white noise excitation and the spatially varying white noise excitation with the Luco–Wong coherence function, the structural filtering effect and the ground motion spatial correlation effect are progressively incorporated, and an analytical interstructural damage correlation model incorporating structural dynamic properties and spatial distance is derived. Comparations with Monte Carlo simulations and existing empirical models demonstrate that the proposed analytical model possesses a clear physical basis and high reliability. Finally, a case study was conducted on a district having 29,461 buildings in Shanghai, China to illustrate the influence of interstructural damage correlation on the regional seismic risk. Results show that disregarding the interstructural seismic damage correlation can lead to underestimation of overall loss uncertainty. [ABSTRACT FROM AUTHOR]

The original single component of seismic data served as the foundation for the majority of previous investigations on the impact of pulse-like ground motion on the dynamic response of structures. The seismic responses of significant infrastructure are less studied when multicomponent motion is taken into account as seismic excitation. As velocity pulses may cause considerable damage to long-period structures, it is of great significance to understand the seismic responses of gravity dams under near-fault pulse-like ground motions for mitigating structural damage. In this study, a unique evaluation approach is suggested for examining the dynamic responses of gravity dams using the combined ground motion of the horizontal and vertical components. Furthermore, the seismic responses of the dam body under rotated and scaled multipulse excitations are investigated. We employed continuous wavelet transform to choose 16 near-fault pulse-like ground motions from actual seismic events with similar amplitude as seismic excitation signals in order to simulate the earthquake damage to the Koyna Dam using the finite-element approach. The displacement, principal stress, and damage fractures of the gravity dam are used to quantify the impact of the pulse intensity variation. The analysis results demonstrate that the structure has remarkable seismic response owing to the presence of large pulse records. The large residual and peak displacements are mainly caused by the velocity pulses and the sensitivity of the upper part of the dam neck to the horizontal relative displacement is significantly higher than that of the lower part. Although the mean intensity parameter of the rotated records with velocity pulse is smaller than that of the Koyna nonpulse, the former increases the mean damage to the dam by 41%. Compared with the rotated records, the scaled records may overestimate the damage of pulse-like motions to the structure, and the stronger pulses are likely to cause severe penetration cracks around the dam neck. The seismic response spectra reveal the potential effects of multicomponent pulse-like motions on the gravity dam and emphasize the significance of considering the combined motion for seismic design. [ABSTRACT FROM AUTHOR]

The transportation hub complex (THC) is an urban landmark building integrating the functions of transportation, commerce, office, and residence. Due to its convenient transportation and diverse service functions, the THC has a certain agglomeration effect in its surrounding areas. Therefore, earthquake damage to the THC will not only affect its own functionality but also impact the connectivity of the regional transportation system, leading to socioeconomic losses in the agglomeration area. To assess the comprehensive impact of THC under earthquake effects, this article considers three aspects: transportation, society, and economy. In terms of the transportation aspect, the impact of the loss of hub function in the THC on the regional transportation system is assessed from three aspects: resource integration capability, radiation scale, and connection efficiency. Subsequently, the agglomeration area generated by the THC is determined based on the kernel density analysis method. The social impact of the THC on its agglomeration area involves three aspects: the reduction of population flow, number of closed shops, and loss of infrastructure resources. The economic impact is measured as the sum of direct and indirect economic losses. Finally, a case study is conducted on a city's THC. The research results indicate that the discontinuation of a subway station in the THC has a greater impact on transportation, society, and the economy. Furthermore, compared with the social service function of the THC, ensuring the hub function after an earthquake can more effectively reduce indirect economic losses. This study can provide a basis for improving the seismic resilience of the THC from the perspectives of regional transportation and socioeconomy. [ABSTRACT FROM AUTHOR]

Displacement response is critical data for post‐earthquake fast building assessment. However, directly measuring building displacement response remains a great challenge in practice. Therefore, it is practically common to estimate displacement response from acceleration response using double integration. Unfortunately, the low‐frequency component of displacement obtained by double integrating acceleration often contains noise that is indistinguishable from low‐frequency displacement components. Consequently, the maximum displacement estimated from acceleration is commonly underestimated in comparison to its true value due to the removal of the low‐frequency components. This can potentially lead to an underestimation of post‐earthquake building damage state, especially when a building undergoes significant nonlinear deformation. This study develops a framework to improve the accuracy of the maximum displacement obtained from floor acceleration data by fusing it with the low‐frequency displacement component estimated from an equivalent SDOF analysis for both reinforced concrete (RC) and steel structures. Procedures for constructing the equivalent SDOF model of a building and a procedure for extracting the low‐frequency component from the analysis displacement were developed. The proposed method was verified using a diverse range of case studies from numerical simulation and experimental studies under different seismic records for both RC and steel structures. The results showed that the proposed method was effective with a range of seismic characteristics and damage levels. A significant reduction in maximum displacement errors was observed for cases with significant nonlinear deformation, which may contribute to a more accurate post‐earthquake building assessment. [ABSTRACT FROM AUTHOR]

The museum system is exposed to a high risk of seismic hazards. However, it is difficult to carry out seismic hazard prevention to protect cultural relics in collections due to the lack of real data and diverse types of seismic hazards. To address this problem, we developed a deep-learning-based multi-source feature-fusion method to assess the data on seismic damage caused by collected cultural relics. Firstly, a multi-source data-processing strategy was developed according to the needs of seismic impact analysis of the cultural relics in the collection, and a seismic event-ontology model of cultural relics was constructed. Additionally, a seismic damage data-classification acquisition method and empirical calculation model were designed. Secondly, we proposed a deep learning-based multi-source feature-fusion matching method for cultural relics. By constructing a damage state assessment model of cultural relics using superpixel map convolutional fusion and an automatic data-matching model, the quality and processing efficiency of seismic damage data of the cultural relics in the collection were improved. Finally, we formed a dataset oriented to the seismic damage risk analysis of the cultural relics in the collection. The experimental results show that the accuracy of this method reaches 93.6%, and the accuracy of cultural relics label matching is as high as 82.6% compared with many kinds of earthquake damage state assessment models. This method can provide more accurate and efficient data support, along with a scientific basis for subsequent research on the impact analysis of seismic damage to cultural relics in collections. [ABSTRACT FROM AUTHOR]

Earthquakes in the Himalayan region predominantly exhibit tectonic characteristics, stemming from fault slippage caused by the ongoing collision between the Indian plate and the Eurasian plate. The western Nepal and adjoining regions (28.5°N to 31.0°N and 78°E to 82.96°E) have hosted the damaging earthquake namely, the 1905 Kangra earthquake, the 1991 Uttarkashi earthquake, and the 1999 Chamoli earthquake in the past and need to understand the recent seismic activity of the region. In this study, we quantified seismic activity in the region from the fractal approach. The key idea of fractal method is based on the self-similarities of objects at different scales. Twelve windows of 100 seismic events with 25-event shifts were analyzed to observe variations in b-value and Dc value for the earthquakes (Mb ≥ 4.0) transpiring between 1964 and 2021. The three consecutive windows from 1991 to 2006 demonstrate a variation in b-value from 0.80 ± 0.07 to 0.90 ± 0.09 and a decrement in Dc value from 1.24 ± 0.03 to 1.20 ± 0.03, indicating a high clustering of earthquakes during the occurrence of major earthquakes, illustrated by the instances like the 1991 Uttarkashi earthquake, the 1999 Chamoli earthquake, and the magnitude 6.1 Mb earthquake in 2004. In addition, the study shows the negative correlation between b-value and Dc value for spatial and temporal distribution of earthquakes in the study region. This study demonstrates the use of b-value and Dc value for identifying seismicity patterns prior to major earthquakes. Continuous monitoring of these seismic patterns could be valuable for assessing the potential seismic hazard and risk throughout the entire Himalayan region. [ABSTRACT FROM AUTHOR]

Earthquakes are one of the most dangerous natural disasters that have constantly threatened humanity in the last decade. Therefore, it is extremely important to take preventive measures against earthquakes. Time estimation in these dangerous events is becoming more specific, especially in order to minimize the damage caused by earthquakes. In this study, a hybrid deep learning model is proposed to predict the time of the next earthquake to potentially occur. The developed CNN+GRU model was compared with RF, ARIMA, CNN and GRU. These models were tested using an earthquake dataset. Experimental results show that the CNN+GRU model performs better than others according to MSE, RMSE, MAE and MAPE metrics. This study highlights the importance of predicting earthquakes, providing a way to help take more effective precautions against earthquakes and potentially minimize loss of life and material damage. This study should be considered an important step in the methods used to predict future earthquakes and supports efforts to reduce earthquake risks. [ABSTRACT FROM AUTHOR]

The single-station microtremor method is one of the fastest, most reliable, and cheapest methods used to identify dynamic soil properties. This study utilizes 49 single-station microtremor measurements to identify the dynamic soil properties of the Hilalkent quarter of the Yakutiye district in Erzurum. Soil dominant frequency and the amplification factor were calculated by using the Nakamura horizontal/vertical spectral ratio (H/V) method. While the soil dominant frequency values varied between 0.4 Hz and 10 Hz, the soil amplification factor changed between 1 and 10. Higher H/V values were acquired with lower frequency values. The vulnerability index (Kg) and shear strain parameters that are utilized to estimate the damage that may be caused by an earthquake were mapped. Especially in the west side of the study area, higher Kg values were observed. The shear strain map was created with 0.25 g, 0.50 g and 0.75 g bedrock accelerations, and soil types that lost elasticity during an earthquake were identified. The average shear wave velocity for the first 30 m (Vs30) was calculated. Finally, it was observed that the western part of the study area, which resulted in a higher period and higher H/V, higher Kg and lower Vs30 values, presents a higher risk of damage during an earthquake. [ABSTRACT FROM AUTHOR]

Quickly and accurately assessing the damage level of buildings is a challenging task for post-disaster emergency response. Most of the existing research mainly adopts semantic segmentation and object detection methods, which have yielded good results. However, for high-resolution Unmanned Aerial Vehicle (UAV) imagery, these methods may result in the problem of various damage categories within a building and fail to accurately extract building edges, thus hindering post-disaster rescue and fine-grained assessment. To address this issue, we proposed an improved instance segmentation model that enhances classification accuracy by incorporating a Mixed Local Channel Attention (MLCA) mechanism in the backbone and improving small object segmentation accuracy by refining the Neck part. The method was tested on the Yangbi earthquake UVA images. The experimental results indicated that the modified model outperformed the original model by 1.07% and 1.11% in the two mean Average Precision (mAP) evaluation metrics,   m A P b b o x 50 and m A P s e g 50 , respectively. Importantly, the classification accuracy of the intact category was improved by 2.73% and 2.73%, respectively, while the collapse category saw an improvement of 2.58% and 2.14%. In addition, the proposed method was also compared with state-of-the-art instance segmentation models, e.g., Mask-R-CNN and YOLO V9-Seg. The results demonstrated that the proposed model exhibits advantages in both accuracy and efficiency. Specifically, the efficiency of the proposed model is three times faster than other models with similar accuracy. The proposed method can provide a valuable solution for fine-grained building damage evaluation. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an innovative deep learning based intelligent software (DamageNet) and its mobile applications to classify seismic damage of Reinforced Concrete (RC) elements. Images of 2455 damaged elements that have been exposed to different destructive earthquakes were collected from the "datacenterhub" database. The DamageNet algorithm has been compared with the pretrained convolutional neural networks (CNN) algorithms (VGG16, ResNet-50, MobileNetV2 and EfficientNet) according to performance metrics. With the other models, a maximum test success of 89% was achieved, while with DamageNet a test success of 92% was achieved in damage classification. The mobile application developed based on the DamageNet model was tested in the field after the earthquakes (Mw:7.7 and Mw:7.6) in Kahramanmaraş/Turkey and classification success of 88% was obtained. [ABSTRACT FROM AUTHOR]