Search Results (195)

Türkiye and Syria were hit by two powerful earthquakes on 6 February 2023. A 7.5 magnitude earthquake, soon followed by a second 7.4 magnitude seism, devastated the area. The present study compares three different entropies using data from 2017 to 2023 (55,823 events) in this region and is the first study to use Shannon entropy, Tsallis entropy, and mutability for analyzing the seismic activity in this region. A couple of years before these large earthquakes, both Shannon entropy and mutability show an overall decrease, potentially indicating upcoming large events; however, the detailed results on mutability offer an advantage, as discussed in this paper. A simultaneous overall increase in Tsallis entropy may also point to some kind of warning of the possible occurrence of large events in the area a couple of years later. The three entropies show how they are presently slowly recovering to previous levels in the affected areas. Longer-term studies combining complementary entropies could help to determine regional seismic risk. Full article

Azerbaijan is known as a hydrocarbon-rich region for its extensive mud volcanoes and complex tectonic settings. In this research, we analyzed a long-term InSAR time-series from Sentinel-1 SAR data spanning January 2017 to October 2024, which revealed the dynamics of active deformation and mud volcanoes. The study area, with its unique geological complexity characterized by rapid eruptions, subsurface pressure, and fault systems, is a one-of-a-kind natural laboratory for examining the interplay between tectonics and mud volcano activity. Based on extensive data collection, the results showed significant deformation on the primary mud volcanoes, such as Ayazakhtarma and Akhtarma-Pashaly. These patterns, characterized by observed subsidence and uplift, result from subsurface pressure fluctuations and hydrocarbon migration. Furthermore, the examination has demonstrated evidence of temporal deformation episodes intricately linked to the periodic buildup and release of subsurface pressures. A significant result of our study was the reactivation of faults and high deformation rate in almost all observed mud volcanoes during the February 2023 Türkiye Kahramanmaraş earthquakes (Mw 7.8 and 7.6). This dynamic far-field triggering effect reactivated faults and induced widespread deformation. This study indicates that the far-field triggering effect has uncovered deformation patterns that persist for several months after the earthquakes, reflecting prolonged subsurface adjustments. The findings demonstrate that mud volcanoes are subsurface fluid dynamics and tectonic stress indicators and have significant practical implications. Overall, the results provide important insights into the reaction of hydrocarbon-rich regions to seismic energy that can be directly applied to improve regional seismic hazard assessments and tectonic studies. By combining different geodetic data with geological interpretations, this work emphasizes the implication of monitoring hydrocarbon-rich regions like Azerbaijan to assess natural hazards and subsurface dynamics, making the research highly relevant and applicable. Full article

The integration of deep learning and remote sensing for the rapid detection of landslides from high-resolution remote sensing imagery plays a crucial role in post-disaster emergency response. However, the availability of publicly accessible deep learning datasets specifically for landslide detection remains limited, posing challenges for researchers in meeting task requirements. To address this issue, this study develops and releases a deep learning landslide dataset using Google Earth imagery, focusing on the impact zones of the 2008 Wenchuan Ms8.0 earthquake, the 2014 Ludian Ms6.5 earthquake, and the 2017 Jiuzhaigou Ms7.0 earthquake as the research areas. The dataset contains 2727 samples with a spatial resolution of 1.06 m. To enhance landslide recognition, a lightweight boundary-focused attention (BFA) mechanism designed using the Canny operator is adopted. This mechanism improves the model’s ability to emphasize landslide edge features and is integrated with the ResUNet model, forming the ResUNet–BFA architecture for landslide identification. The experimental results indicate that the ResUNet–BFA model outperforms widely used algorithms in extracting landslide boundaries and details, resulting in fewer misclassifications and omissions. Additionally, compared with conventional attention mechanisms, the BFA achieves superior performance, producing recognition results that more closely align with actual labels. Full article

As a result of the 2017 Pohang earthquake, numerous piloti-type structures incurred damage, and the cause was attributed to the wide spacing of transverse reinforcement. Improper spacing of transverse reinforcement can lead to brittle failure of columns, potentially causing the collapse of buildings. This study aimed to analyze the failure mode of columns where load and displacement are concentrated due to vertical irregularity, and to quantify the spacing of shear reinforcement according to the degree of vertical irregularity to prevent shear failure of the column. First, a vertically irregular frame with vertical irregularity and an RC moment frame with the same upper and lower structural systems was modeled, and the failure mode of the column was analyzed. In this paper, the failure modes were classified into shear failure, flexure–shear failure, and flexural failure based on the shear capacity ratio. The analysis results showed that in the case of vertical irregularity, the shear demand of the column was evaluated as high due to the high flexural stiffness of the horizontal members, and the failure mode of the column was classified as shear failure. The impact of the spacing of shear reinforcement on the shear strength of the structure was also examined. Next, an analysis was performed according to the degree of vertical irregularity by adjusting the thickness of the first-floor shear wall, and as a result, the proportion of the entire columns classified as shear failure increased as the vertical irregularity increased. It was confirmed that the minimum spacing of shear reinforcement of 150 mm specified in Korean standards becomes inadequate when the degree of vertical irregularity exceeds 2.6. At a vertical irregularity of 8.3, the spacing required to prevent shear failure decreased to 136 mm, which is 9.33% less than the minimum specified by the Korean standards. This indicates that even if the code’s minimum spacing is adhered to, shear failure can still occur in columns. In order to prevent shear failure of the column, the spacing of the shear reinforcement should be designed smaller, because the shear force increases as the vertical irregularity increases. For piloti-type structures with high horizontal irregularity, there is a need to design shear reinforcement narrower than the minimum standard to prevent shear failure of the column. Full article

On 19 September 2017, an intraplate earthquake with a magnitude of Mw = 7.1 occurred in Mexico. Visual inspection reports following the earthquake indicated that 11% of high-risk structures and 35% of collapsed buildings were situated at block corners in Mexico City. This study analyzes the statistics on corner buildings damaged by the 2017 earthquake. Three numerical models of reinforced concrete buildings were developed, featuring four, six, and eight floors with a waffle flat slab floor system. The study focuses on collapsed corner buildings and examines their seismic responses using a series of real unscaled accelerograms from the 19 September 2017 earthquake recorded at seismic stations near these buildings. The nonlinear dynamic analysis showed that seismic demands are concentrated at the more flexible corners of buildings with plan stiffness irregularity, which may result in a collapse at drift ratios lower than those required for more regular structures, indicating low seismic resilience. The study analyzed the progression of seismic demands and damage to corner buildings throughout the 19 September 2017 earthquake, allowing for a numerical verification of the observed damages. Damage indices and the distribution of seismic demands on the buildings clearly correlated with the observed partial and total collapses during the earthquake. Full article

Debris flows are rapid, destructive landslides that pose significant risks in mountainous regions. This study presents a novel algorithm to simulate debris flow dynamics, focusing on sediment transport from 0-order basins to depositional zones. The algorithm integrates the D8 flow direction method with an adjustable friction coefficient to enhance the accuracy of debris flow trajectory and deposition modeling. Its performance was evaluated on three real-world cases in the Otoishi River basin, affected by rainfall-induced debris flows in July 2017, and the Aso Bridge landslide triggered by the 2016 Kumamoto Earthquake. By utilizing diverse friction coefficients, the study effectively captured variations in debris flow behavior, transitioning from fluid-like to more viscous states. Simulation results demonstrated a precision of 88.9% in predicting debris flow paths and deposition areas, emphasizing the pivotal role of the friction coefficient in regulating mass movement dynamics. Additionally, Monte Carlo (MC) simulations enhanced the identification of critical slip surfaces within 0-order basins, increasing the accuracy of debris flow source detection. This research offers valuable insights into debris flow hazards and risk mitigation strategies. The algorithm’s proven effectiveness in simulating real-world scenarios highlights its potential for integration into disaster risk assessment and prevention frameworks. By providing a reliable tool for hazard identification and prediction, this study supports proactive disaster management and aligns with the goals of sustainable development in regions prone to debris flow disasters. Full article

Heritage is strengthened through proactive actions, known as preventive conservation, that are considered before earthquakes, rather than reactive actions addressed when the emergency situation occurs. Considering that there are several regions around the world with very active seismicity, conservation interventions should guarantee human safety and the improvement of the inhabitant’s living conditions while keeping alive the earthen fabric and adobe buildings, thus preserving the lives of the residents but also preserving cultural heritage in the face of earthquakes. The main aim of this paper is to define a comprehensive conservation procedure addressing the preventive conservation of vernacular adobe vaulted houses in Yazd, an Iranian World Heritage property, since 2017. The fundamental phases of this procedure, which this paper’s structure is based on, include introducing the case study and addressing the conservation objectives, the assessment of significance and value, the seismic criteria, the conservation strategies, seismic safety assessment, and decision-making on interventions. The comprehensive preventive conservation procedure presented in this paper was determined by relevant conservation criteria, which contributed to an adequate seismic-retrofitted intervention design. This conservation approach requires evaluation of the seismic performance and the buildings’ safety, through which the decision regarding intervention could be made. Accordingly, this research also dealt with the seismic safety assessment of an adobe building through numerical research work performed using the software HiStrA Ver.2022.1.6. Based on the numerical results, decisions on the need and on the extent of intervention techniques were addressed. In addition, a comparative study was performed on different seismic strengthening techniques available in the literature to define fundamental conservation criteria. In this way, there are more chances for human lives to be preserved if an earthquake occurs. Full article

The increasing frequency of earthquake events worldwide, particularly in South Korea, necessitates detailed seismic hazard assessments to mitigate the risks to urban infrastructure. This study addresses this pressing need by developing a comprehensive multi-hazard assessment framework specific to the Gyeonggi-do Province. By leveraging advanced geospatial computation techniques and geographic information systems, this study integrated geotechnical data, terrain information, and building inventories to evaluate seismic site effects, earthquake-induced landslide hazards, and structural vulnerability. This method uses geostatistical methods to construct geotechnical spatial grids that correlate site-specific seismic responses to potential hazards. The key findings revealed significant variations in seismic site responses owing to local subsurface characteristics, emphasizing the importance of site-specific seismic hazard maps for urban disaster preparedness. The framework’s effectiveness was validated by analyzing the 2017 Pohang earthquake, which demonstrated a strong correlation between predicted and observed damage. This study highlights the importance of ongoing seismic hazard assessment methodology development and advocates interdisciplinary collaboration to improve urban resilience, ultimately protecting communities from the impacts of future earthquakes. Full article

The Central Indian Ocean Basin (CIOB) is distinguished by unusually high tectonic activity, setting it apart from all other passive oceanic basins. Within the interior of the Indo-Australian lithospheric plate lies a unique area of intraplate deformation. This region is characterized by the highest recorded intraplate oceanic seismicity, with earthquake magnitudes reaching up to M = 8, abnormally high heat flow—measured to be two to four times higher than background levels for the ancient oceanic lithosphere of the Cretaceous age—and, most notably, intense folding and faulting of sediments and the basement, which are typically associated only with boundary zones of lithospheric plates. This anomalously tectonically active intraplate area was studied during regular research cruises in the 1970s–1980s, after which new conclusions were mainly drawn from satellite data modeling. Substantially new geophysical data were obtained in 2017 after a long gap. Bathymetric surveys using multibeam echosounders during the 42nd cruise of the R/V (Research Vessel) Akademik Boris Petrov and the SO258/2 cruise of the R/V Sonne provided full coverage of a large portion of the intraplate deformation area in the CIOB. This confirmed the mosaic-block structure of the intraplate deformation zone in the Central Indian Ocean Basin, consisting of numerous isometrically deformed tectonic blocks. A linear block at 0.2–0.6° S, which has a branch-like shape in plain view, is morphologically distinct from these blocks. It represents a system of structural elements of different scales (folds, flexures, ruptures), which constitute a structural paragenesis formed in the mechanical environment of a dextral transpressive tectonic setting. Full article

In recent years, disaster chains caused by glacier movements have occurred frequently in the lower Yarlung Tsangpo River in southwest China. However, it is still unclear whether earthquakes significantly contribute to glacier movements and disaster chains. In addition, it is difficult to measure the high-frequency and large gradient displacement time series with optical remote sensing images due to cloud coverage. To this end, we take the Sedongpu disaster chain as an example, where the Milin earthquake, with an epicenter 11 km away, occurred on 18 November 2017. Firstly, to deal with the cloud coverage problem for single optical remote sensing analysis, we employed multiple platform optical images and conducted a cross-platform correlation technique to invert the two-dimensional displacement rate and the cumulative displacement time series of the Sedongpu glacier. To reveal the correlation between earthquakes and disaster chains, we divided the optical images into three classes according to the Milin earthquake event. Lastly, to increase the accuracy and reliability, we propose two strategies for displacement monitoring, that is, a four-quadrant block registration strategy and a multi-window fusion strategy. Results show that the RMSE reduction percentage of the proposed registration method reaches 80%, and the fusion method can retrieve the large magnitude displacements and complete displacement field. Secondly, the Milin earthquake accelerated the Sedongpu glacier movement, where the pre-seismic velocities were less than 0.5 m/day, the co-seismic velocities increased to 1 to 6 m/day, and the post-seismic velocities decreased to 0.5 to 3 m/day. Lastly, the earthquake had a triggering effect around 33 days on the Sedongpu disaster chain event on 21 December 2017. The failure pattern can be summarized as ice and rock collapse in the source area, large magnitude glacier displacement in the moraine area, and a large volume of sediment in the deposition area, causing a river blockage. Full article

Rapid damage assessment after an earthquake is crucial for allocating and prioritizing emergency actions. Building damage due to an earthquake depends on the seismic hazard and the building’s strength. While it is now possible to promptly access acceleration data as seismic input through online strong motion networks in urban areas, good models are necessary to evaluate the damage in different zones of the affected area. This study aims to present a rapid method for such an urban-scale building collapse evaluation by conducting a nonlinear dynamic analysis of modeled buildings. Based on the Nagato and Kawase model, this study estimates the yield shear strength of 3-story steel buildings, 3-story reinforced concrete buildings, and 1-story masonry buildings in Sarpol-e-Zahab City after the 2017 Mw7.3 earthquake. The damage ratio is calculated through nonlinear dynamic analyses using estimated records from the main earthquake shock in different city zones. The research found that the seismic yield shear strength of steel and reinforced concrete buildings might be weaker than that of the Iranian seismic code’s standard value. Conversely, masonry-building resistance is stronger than the guidelines assumed. The constructed numerical models can be used for the rapid building damage assessment immediately after a damaging earthquake. Full article

The loose integration system of high-rate GNSS and strong-motion records based on Kalman filtering technology is currently a research focus for capturing broadband co-seismic displacements. To address the problem of time-varying system noise variance in the standard Kalman filter (SKF), a variance compensation adaptive Kalman filter (VC-AKF) was adopted in this study to obtain more accurate high-precision broadband co-seismic displacement and provide reliable data support for seismic scientific research and practical applications. The algorithm continuously updates the system noise variance and calculates the state vector by collecting prediction residuals in real time. To verify the effectiveness and superiority of this method, a numerical simulation and a seismic experiment from the 2017 Ms 7.0 Jiuzhaigou earthquake were carried out for comparative analysis. Based on the simulation results, the precision of the proposed algorithm was 46% higher than that of the SKF. The seismic experiment results indicate that the proposed VC-AKF approach can eliminate the baseline shift of accelerometers and weaken the influence of time-varying system noise variance towards more robust displacement information. Full article

Traditional Newmark models estimate earthquake-induced landslide hazards by calculating permanent displacements exceeding the critical acceleration, which is determined from static factors of safety and hillslope geometries. However, these studies typically predict the potential landslide mass only for the source area, rather than the entire landslide zone, which includes both the source and sliding/depositional areas. In this study, we present a modified Newmark Runout model that incorporates sliding and depositional areas to improve the estimation of landslide chain risks. This model defines the landslide runout as the direction from the source area to the nearest river channel within the same slope unit, simulating natural landslide behavior under gravitational effects, which enables the prediction of the entire landslide zone. We applied the model to a subset of the Minjiang Catchment affected by the 1933 M_W 7.3 Diexi Earthquake in China to assess long-term landslide chain risks. The results indicate that the predicted total landslide zone closely matches that of the Xinmo Landslide that occurred on 24 June 2017, despite some uncertainties in the sliding direction caused by the old landslide along the sliding path. Distance-weighted kernel density analysis was used to reduce the prediction uncertainties. The hazard levels of the buildings and roads were determined by the distance to the nearest entire landslide zone, thereby assessing the landslide risk. The landslide dam risks were estimated using the kernel density module for channels blocked by the predicted landslides, modeling intersections of the total landslide zone and the channels. High-risk landslide dam zones spatially correspond to the locations of the knickpoints primarily induced by landslide dams, validating the model’s accuracy. These analyses demonstrate the effectiveness of the presented model for Newmark-based landslide risk estimations, with implications for geohazard chain risk assessments, risk mitigation, and land use planning and management. Full article

Background: Studies evaluating the effects of natural disasters on cancer outcomes are scarce, especially among USA ethnic minority groups, and none have focused on the effects of concurrent natural disasters and the COVID-19 pandemic. The goal of this secondary data analysis is to explore the impact of concurrent exposure to COVID-19 and earthquakes on psychological distress and symptom burden among Puerto Rican cancer survivors. Methods: This secondary data analysis (n = 101) was part of a longitudinal case–control cohort study (n = 402) aimed at describing unmet psychological needs among Puerto Rican cancer patients and non-cancer subjects previously exposed to Hurricane María in 2017. The research team pooled data from participants (cancer survivors and non-cancer group) from their baseline assessments and from follow-up assessments conducted during January–July 2020 (earthquake and the lockdown period). A descriptive, paired t-test, non-parametric mean rank test, and two-sided Pearson correlation analyses were performed. Results: Psychological distress and cancer symptom burden diminished over time. Resilience was significantly correlated with all the psychological and symptom burden variables during both pre- and post-earthquake and COVID-19 assessment periods. Conclusions: The results support the role of resilience, social support, and post-traumatic growth as potential protective factors preventing psychological distress and diminishing cancer symptom burden among cancer survivors exposed to natural disasters and the COVID-19 pandemic. Full article

The 2017 Jiuzhaigou earthquake (Ms = 7.0) struck the eastern Tibetan Plateau and caused extensive concern. However, the reported slip models of this earthquake have distinct discrepancies and cannot provide a good fit for GPS data. The Jiuzhaigou earthquake also presents a good opportunity to investigate the question of how to avoid overfitting of InSAR observations for co-seismic slip inversions. To comprehend this shock, we first used pre-seismic satellite optical images to extract a surface trace of the seismogenic fault, which constitutes the northern segment of the Huya Fault. Then, we collected GPS observations as well as to measure the co-seismic displacements. Lastly, joint inversions were carried out to obtain the slip distribution. Our results showed that the released moment was 5.3 × 10¹⁸ N m, equivalent to Mw 6.4 with a rigidity of 30 GPa. The maximum slip at a depth of ~6.8 km reached up to 1.12 m, dominated by left-lateral strike-slip. The largest potential surface rupture occurred in the center of the seismogenic fault with strike- and dip-slip components of 0.4 m and 0.2 m, respectively. Comparison with the focal mechanisms of the 1973 Ms 6.5 earthquake and the 1976 triplet of earthquakes (Mw > 6) on the middle and south segments of the Huya Fault indicated different regional motion and slip mechanisms on the three segments. The distribution of co-seismic landslides had a strong correlation with surface displacements rather than surface rupture. Full article