Earthquakes In Region Research Articles

Dynamically Triggered Tectonic Tremors and Earthquakes in the Caucasian Region Following the 2023 Kahramanmaraş, Türkiye, Earthquake Sequence

AbstractDeep tectonic tremor has been observed along major subduction zones and several continental strike‐slip faults around the Pacific Rim and the Caribbean. However, it has not be widely identified in other tectonically active regions such as the Alpine‐Himalayan orogenic belt yet. Here we present dynamically triggered tremors and microearthquakes in the Caucasian Region following the 2023 Mw 7.8 and Mw 7.5 mainshocks in the 2023 Kahramanmaraş, Türkiye, earthquake sequence. We observe triggered deep tectonic tremors within Azerbaijan, where seismological evidences suggest pre‐existing subduction slabs. Meanwhile, we document cases of triggered earthquakes in Azerbaijan and Georgia, and Javakheti highland near the border of Georgia and Armenia. These triggered earthquakes are either associated with mud volcanism or volcanic formations. Our results highlight a variety of responses to dynamic stress perturbations, suggesting high susceptibility to dynamic stress perturbations and a broad spectrum of slip behaviors for critically stressed faults in the Caucasian region.

Faulting by the 2023 great earthquakes of Türkiye and associated stress field and its effects on built environment

Abstract Background Faulting induced by earthquakes and its analysis are of great importance for areas with high probability of earthquakes. However, there has been no particularly effective methods to evaluate the damage and applicable solutions for recovery. In this paper, the damage from Türkiye earthquakes is investigated by authors, which has important theoretical significance and practical value. On 6 February, 2023, two successive earthquakes with magnitudes (Mw) of 7.8 (called Pazarcık earthquake) and 7.6 (Ekinözü earthquake) occurred in the south-eastern part of Türkiye. The total length of the surface ruptures was more than 500 km long and resulted in striations reflecting the sinistral faulting and extensive ground deformations. In this study, the authors present the outcomes of the investigations on the surface ruptures, their characteristics, stress field associated with both earthquakes, shear strength property of fault segments and the damaging effects on various structures and made some recommendations with the purpose of how to build structures in active fault zones and decrease the negative effects of faulting on structures. Results Besides summarizing the main characteristics of the world-shaking Kahramanmaraş earthquake doublet in southeast Türkiye in 2023, this study described the main features of the surface ruptures, their relation to the inferred crustal stresses in Türkiye, and the damaging effects on the major engineering structures. The observations and inferences are of great significance for understanding the causes of earthquakes and future seismic risk assessment. Various laboratory experiments were performed on the samples of fault gouge gathered from the sites of surface ruptures and these experimental results provided very valuable quantitative information on the constitutive models of the fault zones. The observations clearly showed that it is almost impossible to prevent damage on structures due to surface ruptures, if certain engineering principles such as increasing higher ductility, lowering gravitational center and/or the implementations of raft foundations are followed. Conclusions The stress state inferences obtained from the striation of the fault surface ruptures as well as from the focal plane solutions are expected to be useful to evaluate the regional stress state of the earthquake region. Assessments indicated that the stress states in Arabian plate and Anadolu platelet are different from each other. However, in-situ direct stress measurement techniques would be quite useful to validate the stress state inferred in this study. The laboratory experiments on samples gathered from the fault outcrops of the earthquakes using direct shear tests, stick-slip tests as well as conventional tensile, compressive and triaxial tests provided the quantitative values for the parameters of constitutive laws for fault zones, which can be utilized in the numerical simulation of earthquakes. If a fault break happens to be just passing underneath the structures, it is almost impossible for mankind to prevent the damage to structures. However, the authors made some recommendations to reduce the negative effects of fault ruptures on structures. These recommendations are such that the structures should be built as ductile and redundant structures with lower center of gravity and raft foundations. Dam construction should be on active faults should be avoided. If they are to be built for whatever reason, they should be of rock-fill type. As tubular structures and tunnels would be generally subjected forced displacement field, it is recommended to utilize flexible joints, segmented and enlargement to deal such displacement fields.

Teleseismic virtual-source reverse time migration of upper crustal structures in the Three Gorges region, China

Summary The Three Gorges (TG) in central China is an earthquake prone region that lacks active-source seismic surveys, hence requiring high-resolution passive seismic imaging to reveal crustal structures in detail. While teleseismic virtual-source reflection (TVR) profiling is effective for imaging gently dipping upper crustal structures, it is unsuitable for mapping steep structures beneath rugged topography in the TG region. Here we develop a teleseismic virtual-source reverse time migration (TV-RTM) to improve the imaging of steep structures. Synthetic tests are conducted to demonstrate the validity and resolution of the TV-RTM method. To mitigate the imaging inaccuracy due to sparse station spacing, we interpolate direct-arrival waveforms to achieve a doubling of the minimally required station spacing from 2 km to 4 km. The TV-RTM images of the upper crustal structure beneath a 2D array in the TG region reveal significant fold and thrust structures that correlate well with the surface geology and tectonic framework. The resolution of the images is assessed using 2D and 3D synthetic models with the station and source geometry of field data. The TV-RTM method provides a new passive seismic solution for studying upper crustal structures in regions that lack active-source seismic data.

Deformation Mechanism in Central China Revealed by Regional Earthquake Tomography

Abstract The central China region (CCN) has experienced significant deformation and complex structural arrangements. We conducted research on the deformation pattern of the CCN through the 3D velocity structure of the crust and uppermost mantle obtained via body-wave tomography. This velocity structure strongly correlates with the region’s topographic features. The relationship between velocity distributions and topography indicates that compression in the east–west direction, which can lead to crustal and mantle shortening, may play a crucial role in shaping topography. The various structures between the Qinling mountain range in the west and the Tongbai–Dabie mountain range in the east highlight distinct geological processes occurring along the Qinling–Dabie orogenic belt. In addition, we propose that reservoir water has infiltrated the crystalline basement rock layer up to 15–20 km beneath the Three Gorges Reservoir. Furthermore, the Three Gorges Dam serves as a solid foundation to prevent reservoir water from seeping downstream underground.

Breastfeeding Experiences of Mothers Staying in Temporary Shelter Areas in Disaster-Affected Provinces in the 2023 Türkiye Earthquake.

While the basic needs of breastfeeding women are similar to those of the general population, there are some specificities that must be taken into account when responding to an emergency. This study examines the breastfeeding barriers faced during a large earthquake in Türkiye and aims to investigate how infant feeding practices of breastfeeding mothers staying in temporary shelters after the earthquake were affected. This study follows a qualitative descriptive design with an inductive approach. It included participants who were older than 18 years of age, had babies no older than 1 year, and were breastfeeding mothers when the earthquake struck. Five main themes were identified through a content analysis of the interviews: (1) breastfeeding environment after the earthquake, (2) emotional impact, (3) change in social relationships, (4) physiological needs and problems, (5) specialized maternal and baby health services. Factors affecting mothers' infant feeding practices were crowded breastfeeding environments, stress and fear caused by the earthquake, decreased breastfeeding support due to changes in social relationships, difficulty in reaching basic physiological needs, and lack of professional health workers in the earthquake region. The most important factor affecting breastfeeding was the lack of suitable environments in which to breastfeed. There should be local, regional, and federal policies to support the privacy needs of displaced breastfeeding mothers.

Deccan Volcanism and Related Seismic Unrest in the Koyna–Warna Region, India

Abstract Koyna–Warna is a region of low-tectonic deformation and normal surface heat flow (∼40 mW/m2) in the Deccan volcanic province, India, where low-to-moderate magnitude earthquakes have continued to occur in the last 60 yr. These earthquakes are uniquely restricted to an 11×16 km2 area and confined to the upper crust between 3 and 9 km depth. Located at the last phase of the interaction of India with the Reunion mantle plume ∼65 Ma ago responsible for extensive volcanism, the cause of sustained seismicity in Koyna region is debated. Using the shear-wave velocity model derived through the joint inversion of the receiver function and surface-wave data from the seismic zone, we propose that earthquakes in the Koyna region occur due to stress concentration arising because of the high-density magma intrusions in the shallow crust at 3–9 km. The high-density mafic-ultramafic body exerts gravitationally induced stress of about ∼12 to 15 MPa. The continuation of earthquakes in the deeper part is inhibited by the possible fluid-filled mush zone imaged as a low-velocity layer at a 9–17 km depth. The magma intrusion as dike can induce a cycle of normal faulting in the overlying rock mass, as observed in the Warna region. We present the first evidence of an extremely high velocity (>4.7 km/s) layer at 40–50 km below Moho, interpreted as the presence of eclogite–peridotite responsible for producing Deccan magma in large volume.

Deep Learning Phase Pickers: How Well Can Existing Models Detect Hydraulic-Fracturing Induced Microseismicity from a Borehole Array?

Summary Deep learning (DL) phase picking models have proven effective in processing large volumes of seismic data, including successfully detecting earthquakes missed by other standard detection methods. Despite their success, the applicability of existing extensively-trained DL models to high-frequency borehole datasets is currently unclear. In this study, we compare four established models (GPD, U-GPD, PhaseNet and EQTransformer) trained on regional earthquakes recorded at surface stations (100 Hz) in terms of their picking performance on high-frequency borehole data (2000 Hz) from the Preston New Road (PNR) unconventional shale gas site, in the United Kingdom (UK). The PNR-1z dataset, which we use as a benchmark, consists of continuously recorded waveforms containing over 38,000 seismic events previously catalogued, ranging in magnitudes from -2.8 to 1.1. Remarkably, all four DL models can detect induced seismicity in high frequency borehole data and two might satisfy the monitoring requirements of some users without any modifications. In particular, PhaseNet and U-GPD demonstrate exceptional recall rates of 95% and 76.6%, respectively, and detect a substantial number of new events (over 15,800 and 8,300 events, respectively). PhaseNet’s success might be attributed to its exposure to more extensive and diverse instrument dataset during training, as well as its relatively small model size, which might mitigate overfitting to its training set. U-GPD outperforms PhaseNet during periods of high seismic rates due to its smaller window size (400-samples compared to PhaseNet’s 3000-sample window). These models start missing events below Mw -0.5, suggesting that the models could benefit from additional training with microseismic datasets. Nonetheless, PhaseNet may satisfy some users’ monitoring requirements without further modification, detecting over 52,000 events at PNR. This suggests that DL models can provide efficient solutions to the big data challenge of downhole monitoring of hydraulic-fracturing induced seismicity as well as improved risk mitigation strategies at unconventional exploration sites.

Ethical issues after the earthquake in Turkey: A qualitative study on nurses' perspectives.

After natural disasters, the urgent need for survival and rescue operations for those trapped in the rubble results in a heightened demand for healthcare services. Nurses are pivotal in addressing the consequences of such calamities. Nurses operating in critical conditions encounter numerous challenges, including safety issues and ethical quandaries. The ethical considerations primarily revolve around the limitations, duties, and modified norms of care administered by nurses during disasters, presenting both significant and complex challenges. The study was designed to elucidate the nature and essence of nurses' care experiences and to offer an in-depth depiction of the ethical dilemmas while attending to individuals injured in the earthquake. A descriptive phenomenological design was used in this research. A total of 16 nurses who worked for at least 7 days in field hospitals in any of the earthquake regions after the 2023 earthquake in Turkey participated in the research. The research was conducted between March 13 and March 20, 2023. Data were collected by face-to-face interview method with a semistructured form. The steps of Colaizzi's phenomenological method were used to analyze the qualitative data. The study involved a group of 16 Turkish nurses, aged between 20 and 36 years. Through data analysis, four primary themes, 14 subthemes, and 25 codes were identified. The principal themes derived from the interviews included "humanitarian duties," "non-adherence to ethical principles," "respect for the injured," and "medical errors." In this intricate process, it becomes paramount to enhance support for nurses in the domains of management, education, and psychosocial assistance, thereby nurturing their individual and professional acumen, commitment, and ethical sensitivity. Refining the guidelines and professional standards that encapsulate the principles to be adhered to by nurses in disaster scenarios, coupled with providing comprehensive training in both medical and ethical competencies, represents a significant avenue for advancement. Focused training on crisis management will enable nurses to render ethically informed decisions and bolster their professional proficiency. Natural disasters, including earthquakes, pose significant ethical challenges for healthcare professionals, especially nurses who play a pivotal role in delivering care during these emergencies. Issues such as resource allocation and triage, the duty of care and ensuring continuity of care, informed consent and communication, cultural sensitivity, and providing psychosocial support are critical ethical considerations for nursing policies in earthquake situations. Addressing these ethical issues in nursing policies related to earthquakes is crucial for maintaining the integrity of healthcare delivery, preserving public trust, and ensuring the well-being of both the injured and healthcare providers during times of crisis.

Onsite Seismic Monitoring Behavior of Undamaged Dams During the 2023 Kahramanmaraş Earthquakes (M7.7 and M7.6).

On 6 February 2023, two major earthquakes struck Türkiye, with their epicenters in the Pazarcık (M7.7; focal depth: 8.6 km) and Elbistan (M7.6; focal depth: 7 km) districts of Kahramanmaraş city. Most of the dams in the earthquake region remained structurally safe and stable. However, 17 dams in Türkiye and 1 dam in Syria were damaged during the 2023 Kahramanmaraş earthquakes. The main objective of this study was to better understand the real seismic behaviors of the dams during the two mainshocks and significant aftershocks. An earthfill dam, a concrete-faced rockfill dam (CFRD), and a roller-compacted concrete (RCC) dam constructed in the disaster area were selected to identify the real seismic behaviors of different types of dams during strong earthquakes. Acceleration records measured at the crest, right and left abutments, and foundations of the selected dams during the 2023 Kahramanmaraş earthquakes were taken into account to determine the real seismic behavior of the dams before, during, and after the earthquakes. The results of this investigation provide valuable insights into the real seismic behaviors of different types of dams in the vicinity of fault lines during strong earthquakes.

HDF5 in the exascale era: Delivering efficient and scalable parallel I/O for exascale applications

Accurately modeling real-world systems requires scientific applications at exascale to generate massive amounts of data and manage data storage efficiently. However, parallel input and output (I/O) faces challenges due to new application workflows and the state-of-the-art memory, interconnect, and storage architectures considered in exascale designs. The storage hierarchy has expanded with node-local persistent memory, solid-state storage, and traditional disk and tape-based storage, thus requiring efficiency at each layer and much more efficient data movement among these layers. This paper discusses how the ExaHDF5 project improved the I/O performance and data management for exascale architectures by enhancing HDF5, a widely used parallel I/O library. The team developed an Asynchronous I/O Virtual Object Layer (VOL) connector that allowed overlapping I/O with computation. They also created a Cache VOL to complement asynchronous I/O by incorporating fast storage layers, such as burst buffer and node-local storage, into the parallel I/O workflow through caching and staging data. Additionally, the team enabled data aggregation and I/O at the node level by using a Subfiling Virtual File Driver (VFD). To demonstrate superior I/O performance with HDF5 at exascale, the ExaHDF5 team collaborated with several exascale applications. In this paper, we show I/O performance improvements for three applications: Cabana (a particle-based simulation library), EQSIM (a regional earthquake simulation software), and E3SM (a climate system modeling library).

Study of seismic activity in the Haiyuan-Liupanshan region using automated microseismic detection techniques

Using continuous waveform data from 27 fixed seismic stations in Ningxia spanning nearly a decade from 2013 to September 2022, the automatic detection matching method (PALM) was employed to capture 34,373 seismic events across the region, which is twelve times more than manual cataloging during the same period. The events were used as a template to search for smaller seismic events in the Haiyuan-Liupanshan region. After location, a total of 14,741 microseismic events were detected. Based on this expanded dataset, we calculated b value and analysis the depth profiles of seismic. The findings indicate that the distribution of microseismicity has characteristics of zonation, clustering and interruption. Seismic activity aligns with active faults and closely correlates with tectonic zones. The areas with seismic gaps and low b-value zones indicate a higher stress level on the north side of the middle section of the Haiyuan Fault, which was also the epicenter of the magnitude 4.9 Pingchuan earthquake on December 31, 2023. The seismic profiles show that the regional earthquakes mainly occur at a depth of more than 30 km. The depth distribution of these earthquakes reflects the inclination of the fault and thus corresponds exactly to the actual conditions.

Quantifying Creep on the Laohushan Fault Using Dense Continuous GNSS

The interseismic behavior of faults (whether they are locked or creeping) and their quantitative kinematic constraints are critical for assessing the seismic hazards of faults and their surrounding areas. Currently, the creep of the eastern segment of the Laohushan Fault in the Haiyuan Fault Zone at the northeastern margin of the Tibetan Plateau, as revealed by InSAR observations, lacks confirmation from other observational methods, particularly high-precision GNSS studies. In this study, we utilized nearly seven years of observation data from a dense GNSS continuous monitoring profile (with a minimum station spacing of 2 km) that crosses the eastern segment of the Laohushan Fault. This dataset was integrated with GNSS data from regional continuous stations, such as those from the Crustal Movement Observation Network of China, and multiple campaign measurements to calculate GNSS baseline change time series across the Laohushan Fault and to obtain a high spatial resolution horizontal crustal velocity field for the region. A comprehensive analysis of this primary dataset indicates that the Laohushan Fault is currently experiencing left-lateral creep, characterized by a partially locked shallow segment and a deeper locked segment. The fault creep is predominantly concentrated in the shallow crustal region, within a depth range of 0–5.7 ± 3.4 km, exhibiting a creep rate of 1.5 ± 0.7 mm/yr. Conversely, at depths of 5.7 ± 3.4 km to 16.8 ± 4.2 km, the fault remains locked, with a loading rate of 3.9 ± 1.1 mm/yr. The shallow creep is primarily confined within 3 km on either side of the fault. Over the nearly seven-year observation period, the creep movement within approximately 5 km of the fault’s near field has shown no significant time-dependent variation, instead demonstrating a steady-state behavior. This steady-state creep appears unaffected by postseismic effects from historical large earthquakes in the adjacent region, although the deeper (far-field) tectonic deformation of the Laohushan Fault may have been influenced by the postseismic effects of the 1920 Haiyuan M8.5 earthquake.

Precise Relocation and Source Characterization of Two Earthquake Sequences in Yellow Sea Using Regional Lg-Wave Observations

ABSTRACT Two significant earthquakes of magnitude ML 4.6 and 4.5 occurred on 18 January and 3 December 2021 in the central region of the Yellow Sea, respectively. The earthquakes occurred beneath the Gunsan sedimentary basin at about 10 km depth with a strike-slip faulting mechanism on nodal planes striking northwest–southeast (NW–SE) and north-northeast–south-southwest (NNE–SSW). Despite a lack of close-by seismographic stations, we successfully utilized regional Lg-wave observations on both coasts of the sea—the Korean peninsula on the east and eastern China on the west. For nine earthquakes in two event sequences, the Lg-wave differential travel times of the nearby event pairs at the common station are carefully measured using the waveform cross-correlation technique. The double-difference earthquake relocation method is employed to obtain precise relative epicentral locations using the Lg correlation measurements. Relocated epicenters align along the NW–SE direction, indicating that the nodal plane striking the same direction is the likely fault plane on which both sequences occurred. This is the first case reported in the literature in which the causative fault plane has been identified for earthquakes in the central Yellow Sea region. It has an important implication for current regional tectonics; it favors neither old tectonic features trending NE–SW (Qianliyan uplift) nor the north–south alignment of significant earthquakes in the region along the Amur plate boundary. The Lg waves from the earthquake sequences are dominant seismic signals on all three-component records at stations in 160–550 km and allowed us to analyze source properties of the two largest earthquakes using the empirical Green’s function approach. Azimuthal variations of the source corner frequencies suggest that earthquake rupture likely propagated toward southeast (125°) along the fault plane, supporting the aftershock relocation results.

Array analysis of P-wave polarization data for constraining near-surface shear wave speeds: Aplication to theValley of Mexico seismic network

SUMMARY We present an array method for constraining near-surface shear wave speed values from P-wave polarization data. As the direction of P-wave particle motion is determined both by the incident ray parameter and the local surficial shear wave speed, the latter can be inferred from three-component seismic records if the ray parameter is estimated first. Previous studies have analysed data recorded at a single station from various earthquakes in order to estimate near-surface shear wave speed. In contrast, this paper analyses data recorded at an array of stations. As such, this method can estimate both ray parameter data for the recorded earthquakes and near-surface shear wave speed values at the studied sites. And as an advantage, the method can analyse records of local and regional earthquakes where ray parameter information cannot be reliably estimated using 1D reference velocity models. Additionally, by processing polarization data spanning multiple events and stations, our method provides robust estimates for near-surface shear wave speed values. We apply this array-based method to a seismic array covering the Valley of Mexico. Analysed records correspond to regional earthquakes with epicentral distances of roughly 300 km. The corresponding ray parameter values for all earthquakes were estimated from the delay of the seismic waves arrival throughout the network as all stations have a reliable time reference. Near-surface shear wave speed values estimated from the array-based polarization analysis are correlated with major geological features of the area such as the Trans-Mexican Volcanic Belt and the local basin. We also apply the presented method to a minimal data scenario. The flexibility of this method allows it to employ a single ray parameter value as input, producing robust estimates for near-surface shear wave speed values within our case study. This feature becomes useful in a variety of scenarios, such as utilizing seismic data lacking timing information. The presented method constitutes an accessible and inexpensive alternative to study shallow seismic structure, opening opportunities to expand and complement current tools and techniques to assess seismic hazards.

New insight into the velocity and anisotropy structures of the subduction zone in northern Sumatra

In this study, we conducted seismic tomographic inversions to investigate the velocity and anisotropy structures of northern Sumatra, using 9774 P-wave and 8405 S-wave arrivals from regional earthquakes. Isotropic P-wave velocity, isotropic S-wave velocity, P-wave azimuthal anisotropy, and P-wave radial anisotropy models were generated using eikonal equation-based traveltime tomography methods. The study identified low-velocity zones beneath the Toba and Sinabung volcanoes, potentially indicating the presence of magma reservoirs. Furthermore, low-velocity anomalies above the subduction slab were detected, which are likely caused by the dehydration of the slab and interpreted as channels of upwelling flow. The tomographic results revealed a trench-parallel high-velocity belt in the uppermost mantle, representing the subducting slab of the India-Australian plate. The trench-parallel fast velocity directions in the slab suggested that the subducted oceanic slab retains its frozen-in anisotropy formed at the mid-ocean ridge, or that the anisotropy is induced by the lattice-preferred orientation of the B-type olivine. Negative radial anisotropy in the mantle wedge was observed, reflecting hot upwelling flows and transitions of olivine fabrics in the presence of water due to slab dehydration. The results also indicated a multilevel magma plumbing system beneath the Toba Caldera. In summary, the results of this study provide new insights into the structure and dynamic processes of the northern Sumatra subduction zone.

Fuzzy Logic-Based Landslide Susceptibility Mapping in Earthquake-Prone Areas: A Case Study of the Mila Basin, Algeria

Abstract —This research focuses on analyzing landslides triggered by a moderate earthquake (Mw = 4.9) in the northeastern region of the Mila province, which resulted in significant damage and economic losses in the El Kherba district and Grarem Gouga city. Through an extensive field-based investigation, a comprehensive inventory of landslides has been compiled. To assess the susceptibility to landslides triggered by seismic activity, a GIS-based fuzzy logic model was employed. The model incorporates various input factors, such as lithology, slope angle, normalized difference vegetation index (NDVI), distance from rivers and roads, precipitation, and seismic hazard, which is shown on a map. The study compares the performance of different fuzzy operators and gamma values and determines that using fuzzy gamma operators with a gamma value of 0.8 yields a satisfactory consistency with the distribution of landslides. Moreover, incorporating the map of seismic hazard as a causative factor enhances the accuracy of landslide susceptibility mapping. This study underscores the utility of the fuzzy logic model in disaster management and the planning of development activities.

Ground Motion Simulation of Scenario Earthquakes in the Nakdonggang Delta Region using a Broadband Hybrid Method and Site Response Analysis

Ground Motion Simulation of Scenario Earthquakes in the Nakdonggang Delta Region using a Broadband Hybrid Method and Site Response Analysis

Professional competences of emergency department nurses working in the earthquake region on triage management in children and the difficulties experienced by nurses in the decision-making process: A qualitative study

Limited resources in disasters may negatively affect the care of paediatric patients and cause complications to be prevented. The aim of this study was to investigate the professional competence of nurses regarding triage management in children during the Kahramanmaraş earthquake and the difficulties they experienced in the decision-making process. This study used a qualitative exploratory research design with a phenomenological approach. In-depth interviews were conducted with the participants individually and through focus group discussions using a semi-structured interview form. A total of 23 participants working in the emergency department during and after the earthquake were included in this study, which was conducted using a purposive sampling technique. Data were analyzed using content analysis procedures. Max Qualitative Data Analysis (2020) programme was used to code the data. As a result of data analysis, 4 main themes and 15 sub-themes emerged. The four main themes were “Professional Competencies of Nurses During Disasters,” “Triage Decision in the Emergency Department,” “Expectations of Nurses Working in a Disaster Area” and “Participation in Disaster Education”. The results of this study showed that nurses are exposed to difficulties arising from many individuals, psychological, professional, environmental, and educational variables in the early period of disaster. Participants' views revealed a strong relationship between being professionally competent, providing appropriate care to patients and emotional exhaustion.

A 3D Seismotectonic Model and the Spatiotemporal Relationship of Two Historical Large Earthquakes in the Linfen Basin, North China

The Shanxi Graben is a transitional zone between the Ordos Block and North China Plain with complex structures and frequent earthquakes. Six earthquakes with M ≥ 7.0 have been recorded in the area, including the 1303 Hongtong M 8 and 1695 Linfen M 7.8 earthquakes in the Linfen Basin. Research on these two large earthquakes, closely related in time and space, is lacking. Our objective was to use deep seismic reflection profiles and 3D velocity structure data from previous research, along with seismological observation results, to interpret the geological structure near the source of the two earthquakes. A 3D geometric model of the seismogenic fault was constructed, and the relationships among the deep and shallow structures, deep seismogenic environment, and two large earthquakes were explored. Differences in seismogenic environment between the southern and northern Linfen Basin were identified. The distribution of small earthquakes in the southern Linfen Basin was scattered, and the overall distribution was at depths <25 km. The small earthquakes in the northern part of the basin were dense and concentrated at depths of 25–35 km. Low-velocity layers at an approximate depth of 15–20 km in the southern basin led to differences in seismogenesis between the two regions. Based on the area of the 3D geometric model of the Huoshan Fault, the maximum magnitude of an earthquake caused by fault rupture is Mw 7.7, so the magnitude of the 1303 Hongtong earthquake might be overestimated. Numerical simulation results of Coulomb stress showed that the 1303 Hongtong earthquake had a stress-loading effect on the 1695 Linfen earthquake. The change in Coulomb rupture stress was 1.008–2.543 bar, which is higher than the generally considered earthquake trigger threshold (0.1 bar). We created a new 3D source model of large earthquakes in the Linfen Basin, Shanxi Province, providing a reference and typical cases for risk assessment of large earthquakes in different regions of the Shanxi Graben.

Quantifying the Pabu Normal Fault Scarp, Southern Tibetan Plateau: Insights into Regional Earthquake Risk

The location of the main boundary fault of the Yadong-Gulu Rift (YGR) shifts from the east side in the southern segment to the west side in the northern segment. The Nyemo Graben Group (NGG) connects the southern and northern segments of the YGR and provides clues for understanding the migration of boundary fault locations along the YGR. However, the NGG has received very little attention. In this study, we map the geometry of the Pabu normal fault, which is the boundary fault of the westernmost graben in the NGG, using high-resolution remote sensing images. We then utilized a digital elevation model (DEM) with a spatial resolution of 1 m. Morphometric parameters such as scarp height, width, and slope were obtained from elevation profiles in three typical deformation regions. Our results reveal a fault segment approximately 3 km long that links the southern and northern segments of the Pabu Fault. Each fault segment could be a major segment. Furthermore, based on regional tectonic activity, the Pabu Fault has the potential to produce an earthquake with a magnitude of around M 6.7.