Earthquake Research Research Articles

Seismic Vulnerability Assessment in Tunnels: A Review

Vulnerability analysis is an important method for earthquake prevention and disaster reduction research in the field of tunnel engineering. Firstly, a detailed overview of the research history and current status of tunnel seismic vulnerability at home and abroad was provided; Secondly, the main methods for analyzing the seismic vulnerability of tunnels at home and abroad were summarized, and the practical applicability of various methods was summarized; Subsequently, the steps for evaluating the seismic vulnerability of tunnels were proposed, and three key contents in establishing theoretical vulnerability curves using numerical simulation as the main method were discussed: (1) Input parameter determination; (2) Classification of destructive states; (3) Calculation of relevant uncertainty parameters; Finally, point out some urgent problems and future research directions in this field. By summarizing the existing studies on the seismic vulnerability of tunnels at home and abroad, the results show that the seismic vulnerability analysis of tunnels can reflect the performance of tunnels under seismic loading by considering the relevant uncertainty factors, which is conducive to the future risk assessment and loss estimation, and is of great significance to the development of performance-based seismic design of tunnels.

Analysis of the b, p values, and the fractal dimension of aftershocks sequences following two major earthquakes in central Himalaya

On April 25 of 2015, earthquake of 7.6 ML struck the central Himalayan region having epicenter at Barpak village in the Gorkha district of Nepal. The event was followed by 7.0 ML earthquake known as Dolakha earthquake, epicenter on the border of Dolakha and Sindhupalchowk. In this study, the b-value, aftershock decay rate p-value, and correlation fractal dimension were estimated for the aftershock sequences. The data used were obtained from the National Earthquake Monitoring and Research Centre (NEMRC), Nepal. The b–values 0.89 ± 0.05 and 0.90 ± 0.07 were computed for aftershocks after Gorkha and Dolakha event, respectively. A significant increase in b-values were reported following the Gorkha earthquake and Dolakha earthquake. The slip procured in the primary fault is respectively 60 % and 56 % after the events. The aftershocks sequences after both events were modelled by the Omori-Utsu law with p = 1.2 ± 0.11 and p = 0.76 ± 0.04. The observed b and p values after the earthquake sequences may correlate well with the large slip experienced by the seismogenic fault. This study sheds light on the mechanism behind the preparation of the significant earthquakes in the tectonic regions of the Himalaya.

Probabilistic Tsunami Hazard Assessment Considering the Sequence of the First and Second Earthquakes Along the Nankai Trough

The Earthquake Research Committee (ERC) of the Headquarters for Earthquake Research Promotion conducted a probabilistic tsunami hazard assessment due to large earthquakes along the Nankai Trough for the next 30 years. Utilizing the basic data of earthquake source models and calculated maximum tsunami heights, the authors propose a method to evaluate the hazard curves of the first and second earthquakes separately, considering the sequence of earthquake occurrence in one cycle of large earthquake activities along the Nankai Trough. First, based on the relative weights allocated to the 176 occurrence patterns of 79 earthquake source regions, the weights for the 2,720 characterized earthquake fault models (CEFMs) are calculated. The hazard curve of the first earthquake is evaluated using the 2,720 sets of maximum tsunami heights and weights under the condition that one of the CEFMs causes an earthquake. Next, the conditional hazard curves for the possible second earthquakes conditional on each individual first earthquake are calculated. Finally, the hazard curve for the second earthquake is evaluated as a weighted average of the conditional hazard curves. Numerical examples are shown for 15 sites. The first earthquake accounts for about 60% or more of the total hazard evaluated by ERC, and its contribution increases with increasing maximum tsunami height. The first and second earthquakes account for 80%–90% of the total hazard.

Research on seismic fragility of subway station based on incremental dynamic analysis method

Seismic intensity measure is an significant parameter that affects the accuracy of structural seismic risk assessment, and plays an important role in the performance-based earthquake engineering research framework. Taking a two story, three span, and shallow buried subway station as the research object, a two-dimensional finite element analysis model of soil structure underground in a typical engineering site was established using ANSYS. Ten earthquake records were selected from PEER as input, and the structural seismic fragility analysis method based on incremental dynamic analysis (IDA) method was introduced into the subway station structure. The maximum story drift angle was used as the structural damage index, and three typical seismic intensity measures were selected, the exploration is conducted on the seismic intensity measures applicable to shallow buried subway stations and the variation pattern of seismic response of subway stations with increasing seismic amplitude. The seismic fragility curve of shallow buried subway station structures is established to obtain the failure probability of the structure at different seismic intensity levels. The analysis results indicate that for shallow buried subway stations, PGA is the most suitable seismic intensity measure, and the comparison with existing empirical fragility curves shows that the vulnerability analysis method is feasible and can quantitatively provide the failure probability of structures at different performance levels, providing reference for seismic design of underground structures.

Remotely imaging seismic ground shaking via large-N infrasound beamforming

Seismic ground motion creates low-frequency atmospheric sound (infrasound) that is detectable at remote sensor arrays. However, earthquake infrasound signal analysis is complicated by interference between multiple waves arriving at sensors simultaneously, reducing the accuracy and detail of ground motion detection. Here we show that individual waves in complicated wavefields can be resolved by recording infrasound on large-N arrays and processing with CLEAN beamforming. Examining both a local (ML3.5, purely tropospheric infrasound propagation) and regional earthquake (ML6.5, upper-atmospheric returns), we detect infrasound from tens of km away and up to several hundred km away respectively. Source regions span arcs of approximately 90°, indicating that although detection bias does occur (most likely from atmospheric winds) the recorded infrasound sources are widely dispersed and not simply epicentral. Infrasound-based remote detection of ground motion over wide areas can complement point measurements by seismometers and spur innovations in earthquake research and real-time hazard monitoring.

Optimal intensity measures in probabilistic seismic demand model of subway station

Ground motion intensity measure (IM), which is a key link between the seismic hazard analysis and structural seismic response analysis, plays an important role in the performance-based earthquake engineering framework. The objective of this paper is to evaluate the most commonly used IMs with respect to their capability to predict the seismic response of underground subway station structures. Because the properties of the surrounding soil has significant influence on the seismic response of subway station structure, four typical classes of engineering sites ranging from Class I to IV according to Chinese code for seismic design of urban rail transit structures are selected in this study. Dynamic time history analyses considering nonlinear soil-structure interaction (SSI) are performed on four two-dimensional finite element models consisting of two-storey three-span subway stations embedded in four different engineering sites in this paper. Both the near-fault without velocity pulse and far-fault ground motions are used as the seismic inputs for the nonlinear SSI models in this study. Ground motion excitation is converted into equivalent seismic load at the artificial boundary for the discretized finite element model to realize the seismic load input. The applicability of 20 ground motion IMs commonly used in earthquake engineering research are investigated in this study. Statistical regression analysis is carried out for those IMs and engineering demand parameters (EDPs) of the subway station structure measured by maximum inter-storey displacement ratio obtained from nonlinear time history analyses. Based on the criteria of efficiency, practicality, proficiency and sufficiency, the optimal IMs in probabilistic seismic demand model that can best estimate the seismic response of the subway station structure are identified among those commonly used IMs. It is found that for sites of Class I and Class II, the Arias intensity followed by the velocity spectrum intensity are the optimal candidates, and for sites of Class III and Class IV, the Arias intensity is the optimal IM.

A call from early‑career Turkish scientists: seismic resilience is only feasible with “earthquake culture”

Despite significant scientific advances in earthquake research and building codes, Türkiye remains vulnerable to earthquakes, as demonstrated by the tragic Kahramanmaraş earthquake in February 2023. In contrast, countries such as Chile and Japan have successfully reduced earthquake damage through strict enforcement of building codes and effective public awareness campaigns. This paper highlights the need for seismic resilience in Türkiye and proposes actionable guidelines to bridge the gap between science and society. These guidelines include comprehensive geoscience education, the establishment of local earthquake centers, effective science communication, preparation for future earthquakes through scenario modeling, and development of an earthquake culture. Geoscience education should be integrated into the education system, and opportunities for geoscientists should be increased. Local earthquake centers can improve seismic monitoring, research, and public outreach. Geoscientists should prioritize science communication training to engage the public and combat misinformation. Scenario modeling and annual preparedness exercises can improve earthquake preparedness across the country, and promoting earthquake memory and awareness initiatives will build a collective consciousness about earthquakes. By implementing these guidelines, Türkiye can build earthquake resilience and mitigate the impact of future earthquakes; however, the active engagement of scientists, institutions, and the public is essential to achieve earthquake resilience.

The effect of the ground motion frequency content on seismic performance and fragility curve of special concentric braced frames

Several articles have investigated the effect of various seismic parameters on the response of the structure. However, there has been limited discussion on the impact of seismic frequency content on the brace failure modes and the collapse mechanism of this system. This study investigated the effect of this parameter, considering three special concentric bracing frames of 2, 4, and 6 stories. For the frame dynamic analysis, the open system for earthquake engineering simulation software (OpenSees) is used. To evaluate the effect of frequency content, 60 earthquake records with high, medium and low frequency content are selected from the pacific earthquake engineering research center ground motion database, considering the peak ground acceleration divided by the peak ground velocity ratio. Incremental dynamic analysis is conducted to draw fragility curves and examine the response of structures.The results indicated that the collapse capacity of structures decreased as the frequency content was reduced. The percentage of reduction in collapse capacity under earthquakes with high to the low frequency content in 2, 4 and 6 story structures were 68, 67 and 71, respectively. In fact, reducing the frequency content increased the probability of occurrence of low cycle fatigue mode in the brace.

Analysis of Publications on Earthquake Research in Architecture Category and Analysis with R Studio-Biblioshiny Software

The purpose of this research is to examine the publications focusing on earthquakes in the category of architecture (web of science). The data of the research was analyzed with the Biblioshiny software program. This software program makes a bibliometric analysis on which topics and concepts earthquake research focuses. In addition, images and frequencies of publications related to architecture and earthquakes were revealed. The data of the research was collected between 1-15 July 2023. Results for Architecture (WoS Categories) AND earthquake* (Topic) OR earthquake AND architecture (Topic) OR earthquake AND house (Topic) OR earthquake AND structure (Topic) OR earthquake AND damage (Topic) OR earthquake AND city (Topic) OR earthquake AND urban (Topic) and Türkiye (Countries/Regions). Data were collected with keywords in the Web of Science database. According to the research findings, there are 1033 publications and in the country/region category (Türkiye), 83 publications are accessed. The most used words in the publications are earthquake, urban transformation, Istanbul, seismic, retrofit, assessment, structural, urban, damage, buildings and performance.

A split Hopkinson pressure bar for experimental investigation of dynamic pulverization under very high strain rates.

Off-fault damage or pulverized rocks found in large-scale strike-slip faults are of great interest in earthquake research. In order to experimentally investigate rock pulverization, we developed a split Hopkinson pressure bar with compact dimensions and high-speed imaging. The developed experimental setup is capable of generating very high strain rates up to 1320s-1 with the satisfaction of stress equilibrium, which are essential to reproduce the dynamic pulverization observed in nature and obtain dynamic stress-strain responses accurately. High-speed imaging revealed that cracks initiate and propagate along the grain boundaries at very high speeds, while the dynamic stress-strain response suggested that energy dissipated into the fracture increases with stronger impacts. In addition, we show that the apparatus is capable of producing particle size distributions partly similar to those in naturally pulverized rocks of large-scale strike-slip faults. Thus, our developed system with compact dimensions opens new ways to understand the dynamics of the rock pulverization in off-fault regions of large-scale strike-slip faults.

Crackling noise microscopy

Crackling noise is a scale-invariant phenomenon found in various driven nonlinear dynamical material systems as a response to external stimuli such as force or external fields. Jerky material movements in the form of avalanches can span many orders of magnitude in size and follow universal scaling rules described by power laws. The concept was originally studied as Barkhausen noise in magnetic materials and now is used in diverse fields from earthquake research and building materials monitoring to fundamental research involving phase transitions and neural networks. Here, we demonstrate a method for nanoscale crackling noise measurements based on AFM nanoindentation, where the AFM probe can be used to study the crackling of individual nanoscale features, a technique we call crackling noise microscopy. The method is successfully applied to investigate the crackling of individual topological defects, i.e. ferroelectric domain walls. We show that critical exponents for avalanches are altered at these nanoscale features, leading to a suppression of mixed-criticality, which is otherwise present in domains. The presented concept opens the possibility of investigating the crackling of individual nanoscale features in a wide range of material systems.

Data Mining Earthquake Prediction with Multivariate Adaptive Regression Splines and Peak Ground Acceleration

Earthquake research has not yielded promising results because earthquakes have uncertain data parameters, and one of the methods to overcome the problem of uncertain parameters is the nonparametric method, namely Multivariate Adaptive Regression Splines (MARS). Sumbawa Island is part of the territory of Indonesia and is in the position of three active earth plates, so Sumbawa is prone to earthquake hazards. Therefore, this research is important to do. This study aimed to analyze earthquake hazard prediction on the island of Sumbawa by using the nonparametric MARS and Peak Ground Acceleration (PGA) methods to determine the risk of earthquake hazards. The method used in this study was MARS, which has two completed stages: Forward Stepwise and Backward Stepwise. The results of this study were based on testing and parameter analysis obtained a Mathematical model with 11 basis functions (BF) that contribute to the response variable, namely (BF) 1,2,3,4,5,7,9,11, and the basis functions do not contribute 6, 8, and 10. The predictor variables with the greatest influence were 100% Epicenter Distance and 73.8% Magnitude. The conclusion of this study is based on the highest PGA values in the areas most prone to earthquake hazards in Sumbawa, namely Mapin Kebak, Mapin Rea, Pulau Panjang, and Pulau Saringi.

Recurrence and Long-Term Evaluation of Kanto Earthquakes

ABSTRACT The 1923 Taisho Kanto earthquake—an interplate event along the Sagami trough where the Philippine Sea plate subducts beneath the Kanto region—produced ground shaking, crustal deformation, landslides, and tsunamis, and caused the worst earthquake disaster in Japan. Based on seismological and geodetic data, many fault models have been proposed, extending ∼100 km from the epicenter, with a moment magnitude (Mw) of 7.8–8.2, and large slips of ∼8 m located near the epicenter and beneath the Miura Peninsula. The penultimate 1703 Genroku Kanto earthquake produced similar macroseismic effects around Sagami Bay and the Miura Peninsula, but larger coastal uplift and tsunami in the Boso Peninsula. The proposed fault models extend off the Boso Peninsula with Mw of 8.1–8.5. In 2004, the Earthquake Research Committee (ERC) classified the Kanto earthquakes as “Taisho type” and “Genroku type” with recurrence intervals of 200–400 yr and 2300 yr, respectively. In 2014, the ERC revised the long-term evaluation to a recurrence interval of 180–590 yr and a 30 yr probability of 0%–5% based on the Brownian passage time model. With the Cabinet Office, the ERC considered the source area of the maximum possible earthquake of Mw 8.6–8.7. The recent historiographical and paleoseismological studies have identified other candidates for the past Kanto earthquakes in 1495, 1433, 1293, and 878. Various combinations of these candidates give a mean recurrence interval of 210–315 yr, an aperiodicity parameter of 0.04–0.76, and a 30 yr probability of 0.0%–19%. The Cabinet Office has calculated the seismic intensity and tsunami heights of various types of Kanto earthquakes. National and local governments estimate the damage from these hazards. For the Tokyo metropolitan area, the estimated damage and occurrence probability are more significant for M ∼7 earthquakes with various types and depths, and most mitigation efforts are directed at such events.

Review on Low-Noise Broadband Fiber Optic Seismic Sensor and Its Applications

Fiber optic seismic sensors have important application prospects in the field of earthquake science research and underground structure detection, due to their strong adaptability in harsh environments such as deep wells, seabeds, and glaciers. It has always been one of the key problems to achieve ultra-low noise levels over a wide measurement frequency band for fiber optic seismic sensors. This article reviews two typical low-noise broadband fiber optic seismic sensing techniques, including narrow-linewidth laser frequency scanning and frequency locking sensing technique, laser interferometric phase interrogation technique. The principles are given. The measurement frequency band and noise level are tested and discussed. Recent progresses on crustal deformation observation, earthquake monitoring, water temperature solid tide detection and deep earth structure exploration based on fiber optic seismic sensors are introduced. Finally, the possible research trends are discussed.

Propagation of crust deformation anomalies related to the Menyuan MS 6.9 earthquake

Decoding the variation laws of the deformation field before strong earthquakes has long been recognized as an essential issue in earthquake prediction research. In this paper, the temporal and spatial distribution characteristics of deformation anomalies in the northeastern margin of the Qinghai-Tibetan Plateau before and after the Menyuan MS 6.9 earthquake were studied by using the Fisher statistical test method. By analyzing the characteristics of these anomalies, we found that: 1) The deformation anomalies are mainly distributed in the marginal front area of the Qinghai-Tibetan Plateau, where short-term deformation anomalies are prone to occur due to a high gradient of gravity; 2) The deformation anomalies along the northeastern margin of the Qinghai-Tibetan Plateau are characterized by spatial propagation, and the migration rate is about 2.4 ​km/d. The propagation pattern is counterclockwise, consistent with the migration direction of MS ​≥ ​6.0 earthquakes; 3) The time and location of the Menyuan earthquake are related to the group migration of earthquakes with MS ​≥ ​6.0. Finally, based on the results of gravity field variation and the theory of crust stress wave, the law of deformation anomaly distribution was discussed. We suggest that both the deformation propagation along the northeastern margin of the Qinghai-Tibetan Plateau and the earthquake migration are possibly associated with the variation of the stress field caused by subsurface mass flow.

Digitizing Ottoman daily weather observations of Halkali Agricultural School in Istanbul, Turkiye (1896–1917)

AbstractDaily weather observations measured by students and staff at Halkali Agricultural School (a school opened in 1892 on agriculture and animal husbandry during the Ottoman period) from 1896 to 1917 in Istanbul, Turkiye have been transcribed from the original publications into digital form and translated from Ottoman Turkish (the Perso‐Arabic script) to English (Latin alphabet). Over 55,000 observations of daily maximum, minimum and average temperature; rainfall, soil and under soil (0.25 m) temperature; humidity, pressure and wind speed were recovered. In addition, weather observations taken in Kandilli Observatory and Earthquake Research Institute from 1911 to 1936 and taken in Florya Meteorological Station from 1937 to 2022 could inform long‐term temperature changes in Istanbul. The publication of a new historical data set that includes, for the first time, digitized and quality‐controlled daily meteorological observations in Istanbul will enhance the understanding of weather changes in Turkiye back to the late 19th century. These observations will be used to fill gaps in existing temperature and pressure records and to the improvement of the accuracy of reanalysis products prior to the 1950s. It will be the first data set publication of other parameters such as soil temperature, wind speed and humidity for that period in that region. Data are available on the CEDA Archive in csv file format.

Earthquake geochemical scientific expedition and research

Large earthquakes can cause both casualties and economic losses, but they also provide invaluable opportunities for earthquake scientific research. Geofluids, due to their wide distribution, sensitive response to underground conditions, and ease of observation, are widely applied in field investigations after earthquakes. Analyzing the origin of fluids, energy transfer processes, temperature/pressure conditions, and the spatial-temporal evolution of geofluids can provide valuable information concerning the mechanism of earthquake precursor anomalies, short-term prediction methods, identification of the seismogenic faults, determination of earthquake risk, and the environmental impact of post-earthquake fluids. This article details post-earthquake scientific expeditions and research on fluid geochemistry in China and abroad, aimed at providing ideas and guidance for future scientific expedition work and geochemistry-related earthquake studies.

Extraction of Building Information Based on Multi-Source Spatiotemporal Data for Earthquake Insurance in Urban Areas

Establishing a database of building exposures is an important basic work in earthquake insurance research. How to efficiently, accurately, and scientifically construct the risk exposure database of buildings has become a hot topic these days. Based on multi-source data, a system for extracting seismic information from urban buildings was constructed in the Tangshan urban area, and a perfect earthquake insurance risk database was established in this study. In the extraction system, the U-net identification method, spatial overlay and kernel density estimation method, Kriging interpolation method, statistical analysis, and multi-temporal land cover data analysis were used, respectively, to extract the information of footprint areas, use function, story number, structure type, and construction age of the urban buildings. The extraction results are stratified and randomly sampled, and the confusion matrix is introduced to verify the extraction effect. The results show that the building covers an area of about 50 million square meters in the urban area of Tangshan City. With the training and validation of the U-net model, the global accuracy of the building footprint areas recognition model is 71%. By comparing the results of manually determined real data with the extraction results of this study for a sample of 660 buildings, it was found that the overall accuracy rates of the extraction results of building function, story number, structure type, and construction age were 88.62%, 86.65%, 86.49%, and 85.58%, respectively, and kappa coefficients were all over 0.8. These indicate that the information on buildings extracted by the method of this study is accurate and reliable. This study can provide data and methods for the establishment of the exposure database of earthquake insurance and provide strong data support for pre-earthquake disaster prevention, post-earthquake emergency rescue, and disaster loss assessment.

Using photovoice for disaster and hazard preparedness: A methodological review

Designing effective policy for public hazard risk communication and preparedness education requires the development of qualitative, participatory, and place-based research methodologies. Traditional research approaches alone cannot fully reveal the situated contexts of different communities that inform understandings of and responses to a range of natural hazard risks. In this paper, we present a review of a novel research methodology, Photovoice, and its potential to engage communities as researchers and co-producers of knowledge. Through auto-photography, researcher-participants document issues affecting their lives and through critical reflexive group dialogue they unveil the underlying causes of issues and develop pathways to enact change. This review outlines the method's theoretical origins, practical application, and prior contributions across disciplines and in hazard research. We then present an Aotearoa New Zealand based pilot study that applies the methodology in a natural hazard context. Research participants took photographs to represent how they perceived the risk of earthquakes and how they prepared for such hazards in their local environments. Participants then engaged in critical reflexive dialogue to reveal the meanings embedded within their photographs, the barriers to preparedness, and opportunities to enact change. The paper reflects on the results of the pilot study, providing insights into the use of the Photovoice methodology in future earthquake and wider hazard research. We argue that Photovoice is an effective methodology for research informing public hazard risk communication and preparedness education due to its ability to reveal place-based insights including risk perceptions, barriers to preparedness, and opportunities to build community capacity and resilience.

EESD special issue: AI and data‐driven methods in earthquake engineering – (Part 1)

EESD special issue: AI and data‐driven methods in earthquake engineering – (Part 1)