Large-scale Earthquakes Research Articles

Seismic capacity evaluation of a reinforced concrete frame infilled with precast modular block wall for enhancing the horizontal load

In this study, we propose a new concept for seismic retrofitting using precast modular block walls (PMBWs) to improve and complement the shortcomings of conventional retrofitting methods for reinforced concrete (RC) frames infilled with shear walls, masonry walls, and precast panels. The PMBW retrofitting method maximizes the advantages of factory-produced modular blocks, innovatively enhancing the constructability and integrity of connections between the existing frame and the infilled PMBW. Additionally, the PMBW reinforcement method improves seismic resistance without significantly increasing structural weight, and the required amount of reinforcement can easily be calculated because the strengthening technique involves typical frame infilling. For RC buildings with non-seismic details dominated by shear failure, the application of this seismic reinforcement method readily ensures sufficient strength. A pseudo-dynamic test was conducted on a full-scale two-story frame, based on an existing RC building with non-seismic details, to evaluate the restoring force characteristics, strength enhancement effects, reinforcement strain, and seismic response control capabilities of the PMBW reinforcement system. Based on the pseudo-dynamic test results, the restoring force characteristics for nonlinear dynamic analysis of the PMBW-reinforced specimen were identified. Finally, nonlinear dynamic analysis was conducted using the proposed restoring force characteristics, and the results were compared with the pseudo-dynamic test results. The unreinforced RC frame experienced shear failure at a design basis earthquake magnitude of 200 cm/s2. However, the frame reinforced with the PMBW sustained only minor damage. Even at higher magnitudes under maximum considered earthquake conditions of 300 cm/s2 and large-scale earthquake conditions of 400 cm/s2, only a slight amount of damage was projected from the analysis. Thus, the newly developed PMBW frame infilling system shows great promise for seismic reinforcement.

Static analysis-based rapid fire-following earthquake risk assessment method using simple building and GIS information

After the occurrences of large-scale earthquakes, secondary damage (e.g., fire following earthquake) can result in tremendous losses of life, properties, and buildings. To reduce these disaster risks, fire following earthquake assessment methods composed of ignition and fire-burned rate estimation models have been utilized. However, previous methods required for large amounts of building and GIS information, and complex modeling and analysis processes, leading to significant time consumption. This paper proposed a static analysis-based rapid fire following earthquake assessment method using simple information and implemented it in Pohang City, South Korea. Based on previous studies, the best-fit model for the ignition rate estimation was selected, and a cluster-based fire-burned rate estimation model was developed using simple building information (e.g., construction year, building occupancy, story, and total floor area) from the public building database (e.g., building registration data). For the fire-burned rate estimation model, fire-resistant structure types were defined using simple building information, and this was utilized to generate clusters of buildings at a regional level by comparing fire-spread distances for each fire-resistant structure type with adjacent distances among the buildings. This proposed method was applied to Pohang City, South Korea, and validated as follows: (1) the selected ignition rate model predicted similar ignition numbers to the actual reported number (actual number of ignitions = 4 vs. predicted number of ignitions = 3), and (2) the fire-burned rate model estimated fire-burned areas with a marginal difference compared to the fire spread simulation (fire-burned area using the proposed model = 13,703.6 m2 vs. results of fire spread simulation = 16,800.0 m2, with an error of approximately 18%).

Pregnant women’s depression and posttraumatic stress levels after the large-scale Turkey earthquakes: a cross-sectional study

ABSTRACT Depression and posttraumatic stress disorder are two common mental disorders after negative life events. This study was conducted to evaluate the depression and posttraumatic stress levels of pregnant women after the large-scale earthquakes that occurred in Turkey in 2023. The study was carried out with 395 pregnant women who visited maternity outpatient clinics of a public hospital in a province in southern Turkey. The data were collected with the Beck Depression Inventory (BDI) and the Post-Traumatic Stress Disorder Checklist – Civilian Version (PCL-C). Descriptive statistics, the independent-samples t-test, and the Pearson correlation test were used in the analyses of the data. Among all participants, 3.8 percent had a likely depression risk, and 31.9 percent exhibited posttraumatic stress disorder symptoms. A statistically significant relationship was found between the earthquake exposure of the participants and their BDI and PCL-C total scores (p < .05). The BDI scores of the participants also had statistically significant relationships to their PCL-C scores (p < .05). In this study, it was discerned that posttraumatic stress disorder symptoms were prevalent among pregnant women in the post-earthquake period. Psychological support is needed to improve the mental health of the pregnant women after earthquakes.

Effect of the Kahramanmaraş earthquake on standing water tanks in the Adana region and buildings in Hatay-Antakya

It is known that the devastating earthquakes experienced in Türkiye in recent years have caused significant loss of life and structural damage throughout the country. Especially the large-scale earthquakes that occurred in Kahramanmaraş on February 6, 2023 and the effects of these earthquakes are examined in detail by researchers. In post-earthquake inspections, it is emphasized that structures such as hospitals and water tanks that need to provide emergency services after the earthquake should be examined in detail and that these structures should be earthquake resistant. In this study, while material-related damages in the structures in the regions affected by the Kahramanmaraş earthquake are examined, the importance of structural improvements, especially in order to increase the earthquake resistance of water tanks, is emphasized. It was also stated that the reasons for the building collapses that occurred after the earthquake in Hatay were discussed in detail. This study makes a valuable contribution to increasing the durability of structures in earthquake risk areas.

Flood risk zoning of cascade reservoir dam break based on a 1D-2D coupled hydrodynamic model: A case study on the Jinsha-Yalong River

Large-scale earthquakes and huge landslide surges may cause the failure of cascade reservoirs, resulting in massive downstream flooding. The flood risk zoning of cascade reservoir dam breaks is crucial for local governments to formulate emergency plans and for individuals to garner their awareness of the flood risks. This paper presents a flood risk zoning approach based on a one-dimensional and two-dimensional coupled hydrodynamic model. The flooding area simulated by the coupled hydrodynamic model was divided into a Deadly Zone (D-zone) and an Escape Zone based on whether there is sufficient time for the public to evacuate the danger area under a specific evacuation generation time (EGT). A case study was conducted on the Jinsha-Yalong River (JYR), a confluence river located in Panzhihua City, to map the risk zones. This study considered a dam-break flood in Yalong River encountering two river flood scenarios in Jinsha River (scenario A: the annual average flow; scenario B: a 1000-year return period flood). Two evacuation scenarios (EGT of 30 and 60 min) were also considered; thereafter, four combined evacuation scenarios (A-EGT30, A-EGT60, B-EGT30, and B-EGT60) were simulated. The coupled hydrodynamic model is demonstrated to be effective through the analysis of water balance and hydrographs of special section discharge. The results show that: (1) in comparison to scenario A, scenario B reached its maximum flood extent approximately 5 min earlier, signifying that flood spread speed increases with the increase in flood magnitude; (2) the D-zone area was 127.7 % larger in scenario A-EGT60 compared to A-EGT30 and 120.8 % larger in scenario B-EGT60 compared to B-EGT30. These findings underscore the importance of flood scenarios and EGT on flood risk zones. The proposed risk zoning method can help government agencies in the JYR and major river regions worldwide with flood management and emergency strategy development.

Evidence for an Imbricated Lower Crust and Its Role in Accommodating Crustal Shortening in Sikkim Himalaya

AbstractGeometrical heterogeneity of the subducting Indian continental crust along the Himalaya‐Tibet collision zone remains enigmatic. Mass budget estimates describing shortening across the orogen are partly derived from observations made from seismic imaging of the deep earth. Here, using data from 38 broadband seismic stations covering Sikkim Himalaya, we produce high resolution seismic images in order to fill crucial gaps in our understanding of the evolution of Himalayan collision zone. We used 12,288 high quality receiver functions computed using waveforms of earthquakes having magnitude &gt;5.5 in the distance range of 30°–100°. Our results reveal a highly imbricated and heterogeneous crust beneath Sikkim Himalaya. The Main Himalayan Thrust (MHT) responsible for large scale earthquakes in the Himalayan collision zone is not so distinct in the migrated images, but intermittent. A dominant cluster of earthquakes at shallower depths is associated with the MHT, marked by negative amplitude arrivals. The Moho is found to be gently dipping, reaching depths of ∼60 km beneath the Higher Himalaya compared to ∼40 km in the Himalayan foredeep. Interestingly, the Moho in this part of Himalaya has offsets and overlapping segments, indicating crustal imbrication in response to active shortening. Clusters of lower crustal earthquakes coincide with the junction of offsets in the Moho.

Analysis of Tsunami Characteristics of Korea Southern Coast Using a Hypothetical Scenario

Large-scale earthquakes are occurring globally, especially in the South Asian crust, which is experiencing a state of tension in the aftermath of the 2011 East Japan Earthquake. Uncertainty and fear regarding the possibility of further seismic activity in the near future have been on the rise in the region. The National Disaster Management Research Institute has previously studied and analyzed the overflow characteristics of a tsunami and the rate of flood forecasting through tsunami numerical simulations of the East Sea of South Korea. However, there is currently a significant lack of research on the Southern Coast tsunamis compared to the East Coast. On the Southern Coast, the tidal difference is between 1~4 m, and the impact of the tides is hard to ignore. Therefore, it is necessary to analyze the impact of the tide propagation characteristics on the tsunami. Occurrence regions that may cradle tsunamis that affect the southern coast region are the Ryukyu Island and Nankai Trough, which are active seafloor fault zones. The Southern Coast has not experienced direct damage from tsunamis before, but since the possibility is always present, further research is required to prepare precautionary measures in the face of a potential event. Therefore, this study numerically simulated a hypothetical tsunami scenario that could impact the southern coast of South Korea. In addition, the tidal wave propagation characteristics that emerge at the shore due to tide and tsunami interactions will be analyzed. This study will be used to prepare for tsunamis that might occur on the southern coast through tsunami hazard and risk analysis.

A digital twin prototype to visualize heterogeneous seismic damage simulation results on web-GIS

ABSTRACT Access to a wide range of information tailored to specific purposes, including extensive damage projections and statistics for target areas and the potential for individual building and dwelling damage predicted through simulations, enhances cities’ resilience against large-scale earthquakes. Recognizing the significance of this, we have developed a prototype of a digital twin capable of comprehensively visualizing various simulations on a web-based geographic information system (GIS) platform. This prototype employs three seismic damage simulators: the Integrated Earthquake Simulation for area damage, the wallstat for wooden houses, and the E-Simulator for a reinforced concrete building. A trial of earthquake damage simulations was conducted to assess this prototype’s efficacy, focusing on the damage incurred in Mashiki Town during the 2016 Kumamoto earthquake. The trial successfully verified the capability of the system to visualize and integrate various types of simulation data alongside records obtained from actual earthquake disasters. This paper provides an overview of the digital twin prototype. It reports on the trial’s results, focusing on the visualization and integration achieved through this trial.

The disaster of the century, Kahramanmaras earthquake: A qualitative study on the experiences of the earthquake victims and search and rescue teams

This study aimed to explore the experiences of earthquake victims who experienced the Kahramanmaras earthquakes and individuals who actively served in search and rescue teams in the field. In this qualitative study, data were collected through semi-structured, in-depth interviews and focus group discussions (FGDs) forms from 47 earthquake victims living in various tent cities and 46 members of search and rescue teams in the Kahramanmaras and Hatay provinces. In-depth individual and focus group interviews were conducted using the maximum variation sampling method, which is a purposive sampling method, to identify the experiences of the participants. Data were analyzed using the content analysis method. The results revealed that search and rescue teams faced problems in coordination and transportation, communication, debris safety, and multidisciplinary reinforcement of their teams, especially during the intervention phase. Earthquake victims, on the other hand, were affected psychosocially and faced many problems such as access to the allocation of resources and aids and lack of information before, during, and after the earthquakes. In this context, these themes on the experiences of large-scale earthquakes that caused great psychosocial, economic, and social devastation from the perspectives of earthquake victims and search and rescue teams can contribute to the planning of early disaster prevention and response strategies for policymakers to improve disaster management at national and international levels.

Field observations on the damage to road bridges after the 2023 Turkey Earthquake

A series of large-scale earthquakes occurred on February 6 in southern Turkey. The authors had the opportunity to join the Japan Disaster Relief (JDR) Expert Team and visit several damaged areas in Turkey from March 10 to 12, 2023. This article highlights damage cases of a road tunnel and several road bridges the authors observed around Antakya, Nurdağı, and Malatya. From the features of the observations, this article discusses the following three items for further study in the seismic design of road bridges: (1) seismic details for robustness, (2) seismic responses of bridges with longer natural periods, and (3) post-event inspection.

Comparative Studies between Frequency Domain Analysis and Time Domain Analysis on Free-Field One-Dimensional Shear Wave Propagation

In Korea, the underground silo structure for low- and intermediate-level radioactive waste disposal facilities has been constructed and operated since 2014. Large-scale earthquakes occurred in 2016 and 2017, respectively, in Gyeongju and Pohang areas near the underground silo structures, and interest in the stability of the underground silo increased significantly. In this paper, one-dimensional free-field analyses have been carried out before the three-dimensional silo dynamic analyses subjected to earthquake loadings. As an additional study, a new form of the finite element equilibrium equation is derived in terms of relative motions, which is essentially the same equation expressed in terms of total motions where the base shear force is applied to the earthquake load. The accuracy of conventional finite element solutions is evaluated by directly comparing them with closed-form solutions by frequency domain analysis such as SHAKE91.

Subsurface Cavities Under Pavement Due to Large-Scale Earthquakes - Characteristics and a Proposal of Non-destructive Evaluation Method -

Subsurface Cavities Under Pavement Due to Large-Scale Earthquakes - Characteristics and a Proposal of Non-destructive Evaluation Method -

Individual Preparedness for Large-scale Earthquakes among International Students in Japan: A Cross-sectional Questionnaire Survey.

Individual preparedness for large-scale earthquakes is essential for safety and security in Japan, where earthquakes frequently occur. Foreign residents in Japan face barriers to gathering disaster information, and international students are likely to be more vulnerable to the effects of earthquakes due to the shorter duration of their stay in Japan. However, no studies have been conducted on international students' individual preparedness for large-scale earthquakes in Japan. This study aimed to investigate individual preparedness for large-scale earthquakes among international students in Japan. This cross-sectional study was conducted from May to August 2023 among 360 international students aged ≥20 years enrolled at seven Japanese-language educational institutions in Osaka, Kyoto, and Hyogo prefectures. Of these, 120 (33.3%) agreed to participate in the mail surveys. Students with invalid answers were excluded and 114 (31.7%) were included in the analysis. The information obtained using a self-administered questionnaire included participants' characteristics, methods used to collect information on individual preparedness for large-scale earthquakes (information sources and languages), and individual preparedness for large-scale earthquakes. Many international students had not implemented safety measures at home and lacked information about safety confirmation, evacuation sites and routes, items to wear during evacuation, items to take in case of evacuation, or items to stockpile at home. In particular, approximately half of the participants lacked knowledge about nearby evacuation sites, and only 37.7% had confirmed their evacuation routes to nearby evacuation sites. Only 32.5% had prepared bags containing emergency items to take in case of an evacuation, and most had not packed the items, even though they were stocked at home. In addition, only 8.8% had stockpiled radios and emergency portable toilets at home. It is necessary to promote individual preparedness for large-scale earthquakes among international students in Japan.

Depression, anxiety, stress, and job performance among Turkish nurses in the early post-earthquake period.

Individual and social concerns can negatively affect nurses' mental health during a large-scale earthquake's early stages, making it challenging to perform their professional responsibilities. This cross-sectional correlational study aimed to examine the relationship between depression, anxiety, and stress levels Turkish nurses experienced during an earthquake's early period. The nurses participating in this study were not directly present in the earthquake-affected area. The study was conducted on 232 nurses between February 10 and 25, 2023. The data were collected using the Depression, Anxiety,Stress-21 Scale and the Job Performance Evaluation Form developed by the researchers through a literature review. These were used to investigate nurses' work motivation changes due to the earthquake. The study followed the STROBE checklist for cross-sectional studies. The participants' depression levels were severe, anxiety levels were extremely severe, and stress levels were moderate following the earthquake. Nurses who felt exhausted experienced reduced energy levels toward their work and reported a decrease in their desire, effort, and work motivation to perform well. In addition, they had higher depression, anxiety, and stress scores (p<0.005). Psychological difficulties, including depression, anxiety, and stress experienced by nurses not directly present in an earthquake-affected area, reduced their professional efforts and motivation and negatively affected the patient care process. Further studies should focus on conducting comparative studies in different cultures affected by natural disasters on the longitudinal analysis of the impacts of nurses' psychological distress on their job performance. Nursing policymakers should be aware of the negative psychological effects experienced by nurses during the early post-earthquake period, even if they are not directly present in the earthquake-affected area. The study recommended that nurses should be provided with psychological support to deal with the negative effects of natural disasters and maintain job performance, including the nursing care process.

A Rapid Earthquake Disaster Assessment Platform Based on Cloud Computing

In the past few decades, earthquakes have been a major cause of casualties and economic losses. The rapid assessment system for earthquake disasters plays an important role in earthquake prevention, disaster reduction, and emergency command by calculating the economic losses and casualties caused by earthquakes in a relatively short time after the occurrence of an earthquake. Although there are now many rapid assessment systems for earthquake disasters, most of them adopt C/S and B/S architectures, which have limited computational efficiency during large-scale earthquakes. Based on these factors, this study aims to build a cloud computing-based rapid assessment system for earthquake disasters. The main modules of the system include intensity impact field calculation, building damage assessment, economic loss assessment, casualties assessment, and model parameter calibration. The results show that the system significantly speeds up the calculation process and shortens the assessment time. It can provide timely disaster assessment information to relevant departments in a short period and provide technical support for emergency decision-making.

Treatment Planning for Victims with Heterogeneous Time Sensitivities in Mass Casualty Incidents

Treatment Planning for Mass Casualty Incidents The existing emergency response guidelines emphasize prioritizing the treatment of victims with initially critical health conditions, but tend to overlook the potential deterioration of less critical victims. Such deterioration can result in prolonged treatment times and irreversible health damages. In “Treatment Planning of Victims with Heterogeneous Time Sensitivities in Mass Casualty Incidents,” Shi, Liu, and Wan draw insights from a unique data set containing timestamps of surgeries conducted in a field hospital established in response to a large-scale earthquake. They develop scheduling models to enhance treatment planning for mass casualty incidents. They identify conditions under which victims with less critical initial conditions may have higher or lower priority than their counterparts in an optimal schedule, aiming to do the greatest good for the greatest number. Through a counterfactual analysis utilizing their data set, the authors demonstrate that implementing their model could significantly reduce surgical makespan, overdue cases, and victim deterioration compared with the previously employed treatment plan.

Community Preparedness Level in the Area Nurul Haq Shelter Against the Threat of Earthquake and Tsunami Disasters

The city of Padang is an area that is prone to earthquakes that have the potential to cause tsunamis. This can be seen from historical data on earthquakes in Padang City. There is a prediction of a large-scale earthquake caused by the Mentawai megathrust fault, where the city of Padang is predicted to be affected by the earthquake and tsunami. Parupuk Tabing is included in the red area if a tsunami disaster occurs. Parupuk Tabing has a shelter to reduce the impact if an earthquake and tsunami disaster occurs. One of them is the Nurul Haq Shelter. Currently, the population around the shelter is around 4,000 people, but the level of preparedness for the dangers of earthquakes and tsunamis is not yet known. This research uses parameters compiled by LIPI – UNESCO 2006, where the parameters tested are; knowledge about earthquake and tsunami disasters, emergency response plans, early warning systems, and resource mobilization. Based on the results of data analysis and research discussions, it was concluded that the level of community preparedness in facing earthquake and tsunami disasters in the area around the Nurul Haq Shelter was included in the very prepared category, namely with an index of 80.97. Then, the knowledge and attitude parameters have a score of 84.78 or "Very Ready", and for the emergency response plan parameters they get a score of 76.57 or "Ready", and for the disaster warning parameters they get a score of 78.36 or "Ready", finally, for the resource mobilization parameter, it got a score of 80.97 "Very Ready". In general, the conclusion is that the community around the shelter understands and is ready to face the threat of earthquakes and tsunamis.

Post-earthquake Patient diversion strategies for improving regional emergency healthcare accessibility

A surge in medical demand after a large-scale earthquake impedes emergency healthcare accessibility. To reduce an unfavourable long wait for medical services, one solution is to redistribute regional medical demand so that the impact can be absorbed by multiple hospitals together. In this paper, discrete event simulations are conducted to experiment with three different patient diversion strategies with the routine method serving as a benchmark. Different aspects of a hospital, either queues at certain medical stages or the overall hospital performance, are monitored for different strategies. To make simulations approximate to real post-earthquake situations, emergency response measures independently carried out by each hospital to increase capacities, including personnel mobilization and vacant beds release, are also considered. Five districts in Taipei City are chosen as the research area for a case study, in which eight first-aid hospitals are located. Based on an earthquake scenario of Richter magnitude 6.6 that would cause this area an estimate of 2361 casualties, results show that the strategy attending to the overall hospital performance is effective in containing waiting time for every medical service. Its effectiveness remains in the sensitivity analysis where beds are decreased. On the contrary, monitoring states of particular medical stages in each hospital to divert patients risks bottlenecks at hospitalization and is sensitive to changes in resource numbers. Findings of this study provide implications for practices of patient diversion after an earthquake, especially on the role of small hospitals and the way to gauge the suitability of hospitals to receive diverted patients.

Development of a Disaster-resilience-based Priority Index Assessment Model for Road Recovery

The concept of disaster response routes for damage reduction has emerged owing to recent large-scale earthquakes. Disaster response routes play an important role in the initial disaster response and recovery by evacuating populations and transferring supplies for disaster response. This study estimated the importance of each road that can be used as a disaster response route after the outbreak of disaster from the viewpoint of disaster resilience and network centrality and developed six types of priority indexes for road recovery based on the purpose of disaster recovery and the function of the disaster response route. Using these priority indexes developed in this study, critical roads for disaster recovery can be identified in short- and long-term periods. Disaster recovery is assumed to improve if disaster response routes are promptly assigned and restored based on these priority indexes.

Earthquake impact on the stress magnitude at the area of shear zones

Both tectonic activity and geological environment such as faulting and shearing in the rock mass influences the in-situ stress condition in the rock mass. The large-scale earthquakes cause both accumulation and sudden release of strain energy resulting the changes on the magnitude and direction of the in-situ stresses. This is the case in the Himalayan region, where the tectonic movement is active and periodic dynamic earthquakes are common. This manuscript assesses the influence of local shear faults on the in-situ stress condition along the pressure tunnel of Upper Tamakoshi Hydroelectric Project in Nepal. For this a 3D numerical modeling is carried out to assess potential changes in the magnitude of in-situ stresses, in particular the magnitude of minimum principal stress, due to dynamic loading (earthquake).