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Background: On September 5, 2022, an Ms 6.8 earthquake occurred in Luding County, Ganzi Tibetan Autonomous Prefecture, Sichuan, China. The casualties and economic losses caused by the earthquake are huge. Most of the landslides triggered by this earthquake are small and medium-sized rock collapses and destructive debris flows, with a small number of large-scale landslides. Results: There are 5007 coseismic landslides in the Luding earthquake VII-degree area and above, with a total area of 17.36 km2. The landslides are generally distributed along the NW-SE direction. The highest landslide area density is 13.8%, and the highest point density of the landslide is 35.73 km2. High-density area is mainly concentrated in the IX-degree area and the northeast side of the seismogenic fault. Coseismic landslides are more likely to develop in the area with the slope more than 40°, the slope direction of 67.5-112.5 degree, and vegetation coverage of 40–50%. More landslides are developed in granite areas and forest areas. The closer distance to active faults, the more the coseismic landslides develop. The correlation between coseismic landslide development and the distance from the active faults is better than that between coseismic landslide development and the distance from the seismogenic faults. Conclusion: The landslide database used in this paper is the most perfect at present, and the research results have also been verified by fieldwork. This is also the first applied study of this landslide inventory, which indirectly confirmed the accuracy of the inventory. The results obtained in the manuscript will provide an important guideline for future disaster prevention and mitigation in southwest China. [ABSTRACT FROM AUTHOR]

On August 20, 2019, at 2 a.m., a disastrous debris flow occurred in Chediguan gully in Yinxing town, China. The debris flow destroyed the drainage groove and the bridge at the exit of the gully. In addition, the debris flow temporarily blocked the Minjiang River during the flood peak, flooding the Taipingyi hydropower station 200 m upstream and leaving two plant workers missing. To further understand the activity of the debris flow after the Wenchuan earthquake, the characteristics of this debris flow event were studied. Eleven years after the Wenchuan earthquake, a disastrous debris flow still occurred in the Chediguan catchment, causing more severe losses than those of earlier debris flows. In this paper, the formation mechanism and dynamic characteristics of this debris flow event are analysed based on a drone survey, high-definition remote sensing interpretations and other means. The catastrophic debris flow event indicates that debris flows in the Wenchuan earthquake area are still active. A large amount of dredging work in the main gully could effectively reduce the debris flow risk in the gully. In addition, it is also important to repair or rebuild damaged mitigation measures and to establish a real-time monitoring and early warning system for the high-risk gully. [ABSTRACT FROM AUTHOR]

The observation of electromechanical coupling might be used as an important tool to detect pre-seismic changes associated with the preparation of earthquakes. This paper attempts to study the electromechanical coupling process before the large earthquakes by using the load/unload response ratio (LURR) approach in which the geo-electric data and Benioff strain of small earthquakes were adopted as the data input. The variation of Coulomb failure stress induced by earth tides on the fault surface of the mainshock is applied to differentiate the loading and unloading stages. Using this technique, we test the geo-electric data recorded at the Hotan observatory near the epicenter of 2020 Yutian Ms 6.4 earthquake. Results show that the LURR time sequence fluctuated around 1.0 for many years and reached significant high peaks at the beginning of 2020. More importantly, this evolution correlates well with the LURR time series calculated by using the Benioff strain of small earthquakes within the circular region of 300 km radius centered at the epicenter. The underlying physics of the changes should be caused by the fluid infiltration derived from pre-seismic rock dilatancy. The corresponding volume variations in the crust could be found in the geophysical observation time series in the same neighborhoods. [ABSTRACT FROM AUTHOR]

Nearly half of coal mine disasters in China have been found to occur in clusters or to be accompanied by earthquakes nearby, in which all the disaster types are involved. Stress disturbances seem to exist among mining areas and to be responsible for the observed clustering. The earthquakes accompanied by coal mine disasters may be the vital geophysical evidence for tectonic stress disturbances around mining areas. This paper analyzes all the possible causative factors to demonstrate the authenticity and reliability of the observed phenomena. A quantitative study was performed on the degree of clustering, and space–time distribution curves are obtained. Under the threshold of 100 km, 47% of disasters are involved in cluster series and 372 coal mine disasters accompanied by earthquakes. The majority cluster series lasting for 1–2 days correspond well earthquakes nearby, which are speculated to be related to local stress disturbance. While the minority lasting longer than 4 days correspond well with fatal earthquakes, which are speculated to be related to regional stress disturbance. The cluster series possess multiple properties, such as the area, the distance, the related disasters, etc., and compared with the energy and the magnitude of earthquakes, good correspondences are acquired. It indicates that the cluster series of coal mine disasters and earthquakes are linked with fatal earthquakes and may serve as footprints of regional stress disturbance. Speculations relating to the geological model are made, and five disaster-causing models are examined. To earthquake research and disaster prevention, widely scientific significance is suggested. [ABSTRACT FROM AUTHOR]

Rapid assessment of the distribution of earthquake-triggered landslides is an important component of effective disaster mitigation. The effort should be based on both seismic landslide susceptibility and the ground shaking intensity, which is usually measured by peak ground acceleration (PGA). In this paper, we address this issue by analyzing data from the Mw6.1 2014 Ludian, China earthquake. The Newmark method of rigid-block modeling was applied to calculate the critical acceleration of slopes in the study area, which serve as measurement of slope stability under seismic load. The assessment of earthquake-triggered landslide hazard was conducted by comparing these critical accelerations with the distribution of known PGA values. The study area was classified into zones of five levels of landslide hazard: high, moderate high, moderate, light, and very light. Comparison shows that the resulting landslide hazard zones agree with the actual distribution of earthquake-triggered landslides. Nearly 70% of landslides are located in areas of high and moderately high hazard, which occupy only 17% of the study region. This paper demonstrates that using PGA, combined with the analysis of seismic landslide susceptibility, allows a reliable assessment of earthquake-triggered landslides hazards. This easy-operation mapping method is expected to be helpful in emergency preparedness planning, as well as in seismic landslide hazard zoning. [ABSTRACT FROM AUTHOR]

The 1718 great Tongwei earthquake in northwest China caused more than 300 large-scale landslides near the epicenter resulting in more than 70,000 deaths. Although previous studies agree that the earthquake-induced landslides in the area are loess-landslides, which slid along ancient terrain surfaces, there is a dearth of evidence to unravel the actual failure mechanisms of these widely-documented events. To clarify their characteristics and mechanisms, the landslides in Pan'an Town, located in Gansu Province, China were rigorously investigated. The field surveys revealed that the landslides occurred in an area comprising loess deposits of several tens of meters underlain by a basal mudstone layer. It was also revealed that instability in the area is strongly influenced by a river valley with large erosion bank slopes, as well as steep mudstone slopes, which are well developed. The majority of the landslides triggered by the Tongwei earthquake were loess-mudstone composite landslides, with the sliding surface in the deep mudstone. Three huge landslides on the northern mountain located at the river bend of Pan'an Town with a total volume of about 6.06 × 10 m are the main mass movements during the 1718 catastrophe. In addition, by taking the typical landslide named the Weijiawan landslide as a case study, the internal structure of the earthquake-triggered landslides and their stability were studied. The new findings not only aided the unraveling of the failure mechanisms but also provided insights and knowledge on early recognition of earthquake-triggered landslides in northwest China towns, especially in the surrounding valley, which shares similar geological conditions with landslides studied in this paper. [ABSTRACT FROM AUTHOR]

In this study, the seismic performance of an ancient pagoda with significant historical and cultural values in China is upgraded by using overall friction pendulum bearing (OFPB) seismic isolation technology, This technique can be used to isolate the pagoda without damaging it. By implementing the OFPB seismic isolation retrofit on the pagoda and comparing and analyzing it with the unretrofitted seismic model, the response of the pagoda under the action of nine seismic waves of three types, namely, near-field earthquakes, far-field earthquakes, and common earthquakes, is investigated. The results show that the OFPB seismic isolation technique significantly reduces the seismic response of the ghats, in which the acceleration amplification factor is reduced by a maximum of 82.46%, the inter-story displacement is reduced by a maximum of 85.15%, and the base shear force is reduced by a maximum of 96.76%. In addition, the tensile damage of the ghats with OFPB seismic isolation was significantly controlled. While the model without seismic isolation has serious damage under the same seismic action and even faces the risk of collapse. The results of the study confirm that the OFPB seismic isolation technology plays a key role in improving the seismic performance of the tower, which is of great theoretical and practical significance to the protection of the tower, and provides an effective technical way for the protection of the tower in the seismic-prone areas. [ABSTRACT FROM AUTHOR]

The inclination of ancient pagodas leads to a non-uniform stress distribution on the soil below. This non-uniform stress threatens the structural stability of the ancient pagodas, and the degree of damage depends on the soil properties. This paper researches the residual strain under the ancient pagodas in China to simulate the non-uniform stress state under frequent earthquake conditions using a dynamic triaxial test apparatus. The non-uniform stress state was expressed by the consolidation stress ratio. The frequent earthquakes were indicated by the dynamic stress ratio and cyclic interval vibration loading. To describe the foundations of the ancient pagodas in China, two types of soil, the mucky clay (Q4) and the paleo-clay (Q3al), were tested. The relationship between the two different soils and the consolidation and dynamic stress ratios were determined by measuring the deformation and accumulated deformation. Additionally, mathematical models to estimate the residual strains of the soils were established and verified. The results indicate that the soil strain increment of mucky clay, which increases with the consolidation stress ratio and dynamic stress ratio, is an important parameter for evaluating the leaning pagodas’ stability in soft soil regions when subjected to frequent earthquake. The soil strain increment of paleo-clay, however, is inversely proportional to the consolidation stress ratio and no apparent relationship is found with the dynamic stress ratio. More research needs to be done on the subsidence of paleo-clay. [ABSTRACT FROM AUTHOR]

The Jishishan Ms 6.2 earthquake occurred at 23:59 on December 18, 2023 in Gansu Province, China. We conducted a field survey to assess the hazards and damages caused by the earthquake and its associated geo-activities. Subsequently, we organized a seminar to discuss the possible causes of the destruction of a prehistoric site—Lajia Settlement—dated back to four thousand years B.P. and located only several kilometers away from the epicenter of the Jishishan earthquake. The Jishishan earthquake was unique for its hazard and disaster process, which featured ground shaking and a series of complex geological and geomorphological activities: sediment and soil spray piles, liquefaction, collapse, landslide, and mudflow along water channels. We define this phenomenon as the Jishishan earthquake ripple hazard (JERH). The most recent evidence from the JERH suggests that a prehistoric earthquake similar to the JERH, instead of riverine floods or earthquake-induced landslide dam outburst flood, as previously hypothesized, destroyed the Lajia Settlement. [ABSTRACT FROM AUTHOR]

China is one of the countries with the longest cultural tradition. Meanwhile, China has been suffering very heavy earthquake disasters; so, there are abundant earthquake recordings. In this paper, we try to sketch out historical earthquake sources and research achievements in China. We will introduce some basic information about the collections of historical earthquake sources, establishing intensity scale and the editions of historical earthquake catalogues. Spatial-temporal and magnitude distributions of historical earthquake are analyzed briefly. Besides traditional methods, we also illustrate a new approach to amend the parameters of historical earthquakes or even identify candidate zones for large historical or palaeo-earthquakes. In the new method, a relationship between instrumentally recorded small earthquakes and strong historical earthquakes is built up. Abundant historical earthquake sources and the achievements of historical earthquake research in China are of valuable cultural heritage in the world. [ABSTRACT FROM AUTHOR]

Earthquakes, as natural phenomena, have consistently caused damage and loss of human life throughout history. Earthquake prediction is an essential aspect of any society's plans and can increase public preparedness and reduce damage to a great extent. Despite advances in computing systems and deep learning methods, no substantial achievements have been made in earthquake prediction. One of the most important reasons is that the earthquake's nonlinear and chaotic behavior makes it hard to train the deep learning method. To tackle this drawback, this study tries to take an effective step in improving the performance of prediction results by employing a novel method in earthquake prediction. This method employs a deep learning model based on convolutional neural networks (CNN), bi-directional long short-term memory (BiLSTM), and an attention mechanism, as well as a zero-order hold (ZOH) pre-processing methodology. This study aims to predict the maximum magnitude and number of earthquakes in the next month with the least error. The proposed method was evaluated by an earthquake dataset from nine distinct regions of China. The results reveal that the proposed method outperforms other prediction methods in terms of performance and generalization. [ABSTRACT FROM AUTHOR]

Abstract  The paper analyzes the characteristics and stability of the Jishixia landslide on the Yellow River in Qinghai Province, China, based on field investigations and various exploratory data. The current stability of the landslide was calculated and the future potential stability was assessed assuming a peak ground acceleration of 0.11g due to an earthquake, and the moisture created by flood discharge from the hydropower station. The results indicate that at present the overall landslide is stable, but further movement could be triggered by an earthquake event and/or significant wetting. [ABSTRACT FROM AUTHOR]

Abstract  This short paper reports some initial fieldwork carried out in four locations shortly after the M8.0 Wenchuan Earthquake which took place on 12 May 2008 in Southwest China. The field evidence, notably that obtained in the town of Xiaoyudong, suggests that the primary motion was related to vertical movement along the Longmenshan Fault. The damage seen was consistent with a right-lateral strike-slip component. [ABSTRACT FROM AUTHOR]

As the largest water conservancy and hydropower project in China, the Three Gorges Reservoir is a weak seismic activity area before impoundment, but the frequency of earthquakes increases significantly after impoundment. The spatial density scanning method was used to obtain the characteristics of spatio-temporal earthquake distribution in the reservoir area during loading and unloading processes. The results show that the frequencies of earthquakes during the loading and unloading processes were higher than that during the low-water-level operation period, which is well explained by the acoustic emission test results. The seismic b-value, fractal dimension D, and spatial correlation length SCL can be used together to indicate stress criticality. To analyze the impacts of reservoir water loading and unloading on seismicity in the reservoir area, time-scan analyses were performed on the b-value, D-value, and SCL of earthquakes near the Zigui segment and the Badong segment. Previous studies argued that the time-varying characteristics of b-values do not hold predictive significance for earthquakes in the M4.0–6.2 range. However, our study found that the time-varying characteristics of b-values are of predictive significance for earthquakes around M4.0. These seismic parameters decrease significantly before moderate earthquakes but at different rates in different regions. [ABSTRACT FROM AUTHOR]

Strong earthquakes in mountainous regions can trigger massive landslides, and not just during the period of shaking. This study uses a time series of remote images to better understand the distribution of landslides near the epicenter of the 2008 Wenchuan Ms8.0 earthquake. We use multi-year high-resolution satellite images to interpret landslides and establish landslide inventories spanning from 2008 to 2019. Based on differencing pre-earthquake and post-earthquake digital elevation models (DEMs), we calculate the factor of safety (Fs, i.e., resisting forces versus driving forces) of slopes using a simplified Newmark model. Results show that landslide occurrence highly relies on slope stability, demonstrated by both co-seismic and post-seismic landslide mapping. According to the Fs analysis, which is closely related to the gradual slope change after the earthquake, most slopes within the study area stabilized after the 2008 Wenchuan earthquake, consistent with the decreasing trend of the landslide activity level. However, due to lithologic variation, the changes of post-earthquake slope stability may differ with landscape features in various regions and result in different geologic hazards. Thus, we highlight the necessity of continuous post-seismic monitoring and analysis of slope stability in different affected regions. The results of this work provide useful information for post-seismic infrastructure reconstruction and future earthquake disaster prevention in mountainous areas. [ABSTRACT FROM AUTHOR]

Details of Pacific plate subduction under the Japan Sea and associated current seismicity remain challenging. Seismic tomography reveals a continuous slab dipping at ~30° down to ~600 km, and earthquake mechanisms point to down-dip compression. Further, the slab is lying at the 660-km discontinuity, and this zone is aseismic. We suggest that this pattern results from the slab's negative thermal buoyancy, resistance of the viscous lower mantle, and buoyancy forces associated with the phase transitions at 410 km and 660 km. Our model comprises an ageing subducting plate, nonlinear rheology and major phase transitions. The model explains the observed low dip angle of the slab and predicts a detailed stress pattern related to bending down to 450 km, followed by unbending as the slab is laid flat upon the 660 km boundary. Remarkably, in the bending/unbending regions, down-dip compression occurs close to the slab top/bottom, respectively. As only down-dip compression is observed, we argue that the earthquakes are mapping the top and bottom of the slab. The absence of seismicity in the flat-lying slab is explained by significantly lower stresses and higher temperatures. With this new knowledge, increasingly accurate seismic locations will considerably improve images of finite-extent slab geometry. [ABSTRACT FROM AUTHOR]

Immediately after a destructive earthquake, the real-time seismological community has a major focus on rapidly estimating the felt area and the extent of ground shaking. This estimate provides critical guidance for government emergency response teams to conduct orderly rescue and recovery operations in the damaged areas. While considerable efforts have been made in this direction, it still remains a realistic challenge for gathering macro-seismic data in a timely, accurate and cost-effective manner. To this end, we introduce a new direction to improve the information acquisition through monitoring the real-time information-seeking behaviors in the search engine queries, which are submitted by tens of millions of users after earthquakes. Specifically, we provide a very efficient, robust and machine-learning-assisted method for mapping the user-reported ground shaking distribution through the large-scale analysis of real-time search queries from a dominant search engine in China. In our approach, each query is regarded as a "crowd sensor" with a certain weight of confidence to proactively report the shaking location and extent. By fitting the epicenters of earthquakes occurred in mainland China from 2014 to 2018 with well-designed machine learning models, we can efficiently learn the realistic weight of confidence for each search query and sketch the felt areas and intensity distributions for most of the earthquakes. Indeed, this approach paves the way for using real-time search engine queries to efficiently map earthquake felt area in the regions with a relatively large population of search engine users. [ABSTRACT FROM AUTHOR]

A catastrophic loess flow slide was triggered by the 2013 Minxian–Zhangxian earthquake in Yongguang village, Minxian County, Gansu Province, China. The landslide destroyed eight houses and killed 12 persons. The landslide involved the failure of 14.0 × 104 m3 of loess deposits from the source area. The displaced materials traveled 1000 m with an elevation descent of 180 m, covering an area of 4.2 × 104 m2. A numerical model (DAN3D) is used to simulate the post-failure behavior of the landslide based on a detailed field investigation. A combination of the frictional model and Voellmy model provides the best performance in simulating the landslide using trial and error. The simulation results indicate that the landslide lasted approximately 120 s and had an average velocity of 8.3 m/s. The final runout distance and deposit distribution are in a good agreement with the actual situation, indicating the accuracy of the simulated results. Therefore, it is expected that the models and parameters could improve the precision of hazard zonation for areas with geological, topographical, and climatic features similar to the Yongguang landslide area. [ABSTRACT FROM AUTHOR]

Ma’an Qiao Village, a Dai and Yi ethnic minority-based community in Sichuan Province, China sustained complete infrastructure devastation during the 2008 Panzhihua earthquake. Health emergency and disaster risk management (Health-EDRM) education intervention programs were implemented in 2010 and 2011. This serial cross-sectional survey study aimed to examine the immediate and long-term impacts of the Health-EDRM interventions in this remote rural community. The findings demonstrate knowledge improvement in areas of water and sanitation, food and nutrition, and disaster preparedness immediately after the Health-EDRM education interventions. Temporal stability of knowledge retention was observed in household hygiene and waste management and smoking beliefs in 2018, 7 years after the interventions. Other important findings include knowledge uptake pattern differences of oral rehydration solution (ORS) between earthquake-prone and flood-prone communities. Usage of Internet and mobile technology for accessing disaster-related information was found to be independent of gender and income. Overall, this study demonstrated the knowledge improvement through Health-EDRM education interventions in a remote rural community. Promoting behavioral changes through interventions to raise awareness has the potential to reduce health risks in transitional post-disaster settings. Future programs should aim to identify evidence-based practices and explore how technology can support Health-EDRM education among vulnerable subgroups. [ABSTRACT FROM AUTHOR]

Disaster damage assessment is an important basis for the objective assessment of the social impacts of disasters and for the planning of recovery and reconstruction. It is also an important research field with regard to disaster mitigation and risk management. Quantitative assessment of physical damage refers to the determination of the physical damage state of the exposed elements in a disaster area, reflecting the aggregate quantities of damages. It plays a key role in the comprehensive damage assessment of major natural hazard-induced disasters. The National Disaster Reduction Center of China has established a technical work flow for the quantitative assessment of disaster physical damage using remote sensing data. This article presents a quantitative assessment index system and method that can be integrated with high-resolution remote sensing data, basic geographical data, and field survey data. Following the 2014 Ludian Earthquake in Yunnan Province, China, this work flow was used to assess the damage to buildings, roads, and agricultural and forest resources, and the assessment results were incorporated into the Disaster Damage Comprehensive Assessment Report of the 2014 Ludian Earthquake for the State Council of China. This article also outlines some possible improvements that can be addressed in future work. [ABSTRACT FROM AUTHOR]

In the northwest of China, many loess landslides have occurred without clear triggering factors (i.e., rainfall, earthquake, human activities, etc.). To better understand and analyze the hydro-mechanical properties of these slopes and then provide evidence for their stability analysis subjected to matric suction, it is essential to clarify the soil-water characteristic curve (SWCC). In this study, we conducted a set of experimental trials to examine the influences of initial dry density, water content upon the SWCCs of a loess soil taken from a loess landslide area, by using a conventional volumetric pressure plate extractor. Two common SWCC models have been investigated to evaluate which one is better for loess soil. The suction stress characteristic curves (SSCCs) were also estimated and analyzed. We found that behaviors of SWCCs would be different when the matric suction was greater than a certain value. The two SWCC equations have approximately the same performance in describing the SWCC. The rates of desorption decrease and residual water content increases with increasing the initial dry density, while the initial dry density has little, if any, influence on the air-entry value (AEV). The specimen compacted under higher initial water content would exhibit a higher AEV value and residual water content but lower rate of desorption as compared with the lower initial water content. The magnitude of suction stress had an approximately linear relationship with matric suction before the AEV value, the SSCC shapes will be markedly varied with the initial dry density and water content. [ABSTRACT FROM AUTHOR]

The mainshock of April 20, 2013 Sichuan Lushan M7.0 earthquake was relocated using a 3-D velocity model. Double difference algorithm was applied to relocate aftershock sequences of Lushan earthquake. The locations of 2405 aftershocks were determined. The location errors in E-W, N-S and U-D direction were 0.30, 0.29 and 0.59 km on average, respectively. The location of the mainshock is 102.983°E, 30.291°N and the focal depth is 17.6 km. The relocation results show that the aftershocks spread approximately 35 km in length and 16 km in width. The dominant distribution of the focal depth ranges from 10 to 20 km. A few earthquakes occurred in the shallow crust. Focal depth profiles show fault planes dip to the northwest, manifested itself as a listric thrust fault. The dip angle is steep in the shallow crust and gentle in the deep crust. Although the epicenters of aftershocks distributed mainly along both sides of the Shuangshi-Dachuan fault, the seismogenic fault may be a blind thrust fault on the eastern side of the Shuangshi-Dachuan fault. Earthquake relocation results reveal that there is a southeastward tilt aftershock belt intersecting with the seismogenic fault with y-shape. We speculate it is a back thrust fault that often appears in a thrust fault system. Lushan earthquake triggered the seismic activity of the back thrust fault. [ABSTRACT FROM AUTHOR]

Following the Lushan M7.0 earthquake on 20 April 2013, a topic of much concern is whether events of M7 or greater could occur again on the southern segment of the Longmenshan fault zone. In providing evidence to answer this question, this work analyzes the tectonic relationship between the Lushan event and the 2008 Wenchuan earthquake and the rupture history of the southern segment of the Longmenshan fault zone, through field investigations of active tectonics and paleoearthquake research, and our preliminary conclusions are as follows. The activity of the southern segment of the Longmenshan fault zone is much different to that of its central section, and the late Quaternary activity has propagated forward to the basin in the east. The seismogenic structure of the 2008 Wenchuan earthquake is the central-fore-range fault system, whereas that of the 2013 Lushan event is attributed to the fore-range-range-front fault system, rather than the central fault. The southern segment of the Longmenshan fault zone becomes wider towards the south with an increasing number of secondary faults, of which the individual faults exhibit much weaker surface activity. Therefore, this section is not as capable of generating a major earthquake as is the central segment. It is most likely that the 2013 earthquake fills the seismic gap around Lushan on the southern segment of the Longmenshan fault zone. [ABSTRACT FROM AUTHOR]

At 14:34 Beijing time on February 27, 2010, an earthquake of Mw 8.8 rocked the central coast of Chile. A teletsunami was triggered by the huge earthquake and then propagated across the entire Pacific in less than 24 h. The initial tsunami wave arrived at the southeast coast of China at 16:20 on February 28 and was recorded in real time by a number of tidal gauges off mainland China and Taiwan Province. The teletsunami waves have never been recorded with such a broad geographical scope in China before this event. The aim of the present work is to report the first description of sea-level oscillations generated by the Chile tsunami, and evaluate the potential hazards that teletsunami poses to the coast of China. The results reveal that the east coast of Taiwan Province, Zhejiang Province and the north coast of Fujian Province are vulnerable to transoceanic tsunami. In addition, spectral and wavelet analysis of the recorded sea-level oscillations shows that "seiches" are easily excited by the resonance resulting from the interaction between the initial tsunami waves and local geometry (such as semi-enclosed bays and ports). The superimposition of the two oscillations would amplify the wave height further. [ABSTRACT FROM AUTHOR]

It has been assumed that Himalayan earthquakes are driven by the release of compressional strain accumulating close to the Greater Himalaya. However, elastic models of the Indo–Asian collision using recently imaged subsurface interface geometries suggest that a substantial fraction of the southernmost 500 kilometres of the Tibetan plateau participates in driving great ruptures. We show here that this Tibetan reservoir of elastic strain energy is drained in proportion to Himalayan rupture length, and that the consequent growth of slip and magnitude with rupture area, when compared to data from recent earthquakes, can be used to infer a ∼500-year renewal time for these events. The elastic models also illuminate two puzzling features of plate boundary seismicity: how great earthquakes can re-rupture regions that have already ruptured in recent smaller earthquakes and how mega-earthquakes with greater than 20 metres slip may occur at millennia-long intervals, driven by residual strain following many centuries of smaller earthquakes. [ABSTRACT FROM AUTHOR]

The rocks of the Indian subcontinent are last seen south of the Ganges before they plunge beneath the Himalaya and the Tibetan plateau. They are next glimpsed in seismic reflection profiles deep beneath southern Tibet, yet the surface seen there has been modified by processes within the Himalaya that have consumed parts of the upper Indian crust and converted them into Himalayan rocks. The geometry of the partly dismantled Indian plate as it passes through the Himalayan process zone has hitherto eluded imaging. Here we report seismic images both of the decollement at the base of the Himalaya and of the Moho (the boundary between crust and mantle) at the base of the Indian crust. A significant finding is that strong seismic anisotropy develops above the decollement in response to shear processes that are taken up as slip in great earthquakes at shallower depths. North of the Himalaya, the lower Indian crust is characterized by a high-velocity region consistent with the formation of eclogite, a high-density material whose presence affects the dynamics of the Tibetan plateau. [ABSTRACT FROM AUTHOR]

On January 19, 2020, an Mw 6.0 earthquake occurred in Jiashi, Xinjiang Uygur Autonomous Region of China. The epicenter was located at the basin-mountain boundary between the southern Tian Shan and the Tarim Basin. Interferometric Synthetic Aperture Radar (InSAR) is used to obtain the coseismic deformation field from both ascending and descending Sentinel-1A satellite images of the European Space Agency. The results showed that the coseismic deformation is distributed between the Kalping fault and the Ozgertaou fault. The earthquake produced significant deformation over an area of approximately 40 km by 30 km. The maximum and minimal displacements along the line of sight (LOS) are 5.3 cm and − 4.2 cm for the ascending interferogram and are 7.2 cm and − 3.0 cm for the descending interferogram, respectively. The fault geometry from the Multi peak Particle Swarm Optimization computation indicates that the seismogenic fault is a shallow low-dipping planar fault that is 4.58 km depth underground. The finite slip model inverted by the Steepest Descent Method implies that the rupture is dominated by a thrust fault. The slips are concentrated in a depth of 5–7 km with a maximum slip of 0.29 m. The estimated total seismic moment is 1.688 × 1018 Nm, corresponding to a magnitude of Mw 6.1. The seismogenic fault is the Kalping fault which has a listric structure. The coseismic deformation only occurred on the décollement layer and did not involve the ramp segment. The coseismic Coulomb stress changes have enhanced the stress on the deep margin of the Jiashi earthquake rupture area, indicating that there is still the possibility of strong earthquakes in this region in the future. [ABSTRACT FROM AUTHOR]

On 3 July 2015, the Mw 6.5 Pishan earthquake occurred at the junction of the southwestern margin of the Tarim Basin and the northwestern margin of the Tibetan Plateau. To understand the seismogenic mechanism and the post-seismic deformation behavior, we investigated the characteristics of the post-seismic deformation fields in the seismic area, using 9 Sentinel-1A TOPS synthetic aperture radar (SAR) images acquired from 18 July 2015 to 22 September 2016 with the Small Baseline Subset Interferometric SAR (SBAS-InSAR) technique. Postseismic LOS deformation displayed logarithmic behavior, and the temporal evolution of the post-seismic deformation is consistent with the aftershock sequence. The main driving mechanism of near-field post-seismic displacement was most likely to be afterslip on the fault and the entire creep process consists of three creeping stages. Afterward, we used the steepest descent method to invert the afterslip evolution process and analyzed the relationship between post-seismic afterslip and co-seismic slip. The results witness that 447 days after the mainshock (22 September 2016), the afterslip was concentrated within one principal slip center. It was located 5–25 km along the fault strike, 0–10 km along with the fault dip, with a cumulative peak slip of 0.18 m. The 447 days afterslip seismic moment was approximately 2.65 × 1017 N m, accounting for approximately 4.1% of the co-seismic geodetic moment. The deep afterslip revealed that a creeping process from steady-state "secondary" creeping to accelerating "tertiary" creep in the deep of fault. The future seismic hazard deserves further attention and research. [ABSTRACT FROM AUTHOR]

Recent magnetic satellite missions facilitate new birth of large-scale geomagnetic field models and their applications to tectonics. Here, we directly compare the global geomagnetic field models NGDC-720 with the tectonics and seismicity in Mainland China and surroundings. It is found that the tectonics and seismicity in this area show remarkable correlation with the vertical component of lithospheric magnetic field (Bz) calculated at an altitude of 200 km. Previous thought was that earthquakes are more likely to occur in zero Bz belts or in obvious anomaly gradient belts. On the contrary, we find that more than half (53.2%) of the earthquakes occurred in areas with Bz of − 5 to − 3 nT or in areas with a relatively small horizontal gradient of Bz in the same time interval with the satellite data. The percentage seismic energy in these areas (− 5 nT < Bz < − 3 nT) is even as high as 94.6%. We explain this unexpected result with a two equivalent source dipole model, arguing that the viscosity difference caused by the temperature gradient within the lithosphere likely accounts for the correlation between magnetic anomalies and seismicity. [ABSTRACT FROM AUTHOR]

In this study, the strong ground motion of the Jiuzhaigou Ms7.0 earthquake, which occurred in northern Sichuan, China, was simulated based on the stochastic finite-fault method. The earthquake event was recorded by 66 strong ground-motion stations operated by the China Strong Motion Networks Center. We simulated 11 records selected within 200 km source-to-site distance. According to previous studies and empirical relationships, we estimated the region-specific input parameters. The zero-distance kappa filter obtained had a value of 0.0206 s. Two different source models were applied in this study: the random slip model and specified slip model. Using the stochastic finite-fault method, we simulated the PGA, Fourier spectrum and response spectrum at all stations. The stochastic simulated result based on the specified slip distribution models had no significant bias at most stations. Using a model with a random slip distribution, the simulated response spectra also matched the observed result, which indicated that the stochastic finite-fault method is not very sensitive to the input slip distributions and fault dimensions. We divided the study area into 1116 sites to simulate the spatial distribution of PGA based on the two models. The simulated maximum intensity of the epicentral area reached level IX, which was similar to the observed maximum intensity and indicated that the simulated result could be used in prediction of an imminent earthquake disaster. For future earthquake prediction, seismic hazards could even be estimated quickly without obtaining detailed information about the fault plane. [ABSTRACT FROM AUTHOR]

The article reports on the findings of the study about the geometrical measurrement of earthquake, conducted by a team led by Zheng-Kang Shen of the China Earthquake Administration in Beijing, China. The results of the study led the researchers to pin down the geometry of the fault that ruptured in Sichuan province in May 2008 in China that killed at 70,000 people. The study also found out that maximum slip happened at the intersections of different fault segments in the different areas of the said province.