M8.0,the earthquake of M8.8 in Chile,the Tohoku earthquake of M9.0 in Japan,the M8.1 earthquake in Nepal,the 2016 M7.3 Kyushu earthquake of and the doublet earthquakes of both M7.8 in 2023 in Turkiye. The regional reference frames are used in studies on the crustal deformations precursory to earthquakes to keep alignment for the requirement. And the coseismic horizontal displacements are the key phenomenon in exploring crustal deformations precursory to earthquakes. No accumulations of vertical and horizontal shear displacements were detected at or near the epicenters. There have been two patterns of precursory horizontal displacements at and near the epicenters of large earthquakes,that is,they reached peak values or were locked with no horizontal displacements. The media at and near the epicenters were non-elastic,but the media far from the epicenter were elastic. The GNSS observations showed that the epicentral areas were compressed before the events and there were shear break at the time of the earthquakes. The processes were similar to the rock failures in the rock tests. Therefore the “compression-shear”(elastic)rebound model is in agreement with the results of GNSS observations. But till now there were imminent precursory crustal deformations for only quite few earthquakes. Obviously even though there are problems in detecting imminent precursory deformations,GNSS has been one of the main observation techniques in earthquake forecasting. Because imminent precursory deformations are closely related with critical phenomenon in the failure process of earthquake faults,the critical phenomenon or imminent precursors are the key for the breakthrough in earthquake forecasting. Different observation techniques of multiple disciplines should be used to detect the imminent precursors.]]> 2024/1/8 11:35:44 R>R₀ of 11 test items can be used as key test items for daily tracking anomaly in northeast Yunnan. It was concluded that most such the shallow precursor anomalies were caused by fluid force induced by atmospheric precipitation.]]> 2024/1/8 11:35:45 2024/1/8 11:35:45 P＜0.001). The results of test data revealed that physical conformity and familiarity were the critical factors affecting sign comprehension rates. We concluded that the physical conformity,conceptual conformity,and familiarity of logo graphics should be improved first to enhance the effectiveness of the logo. Finally,some of the signs in GB/T24362-2009 with low comprehension rates were analyzed with ergonomic principles,and specific suggestions for improved design were put forward.]]> 2024/1/8 11:35:45 2024/1/8 11:35:45 2024/1/8 11:35:45 2024/1/8 11:35:45 2024/1/8 11:35:45 v_p/v_s model consistency-constrained double-difference seismic tomography method with the earthquake catalogue and phase report constructed by machine learning and t,to obtain the seismic location and 3D v_p,v_s,v_p/v_s structures in the reservoir areas of western Guizhou Province. The results show that the velocity structures in the study area are of obvious heterogeneity,and different tectonic deformation zones show different velocity structure characteristics. At the depth of less than 10km,the NW-trending Weining tectonic deformation zone that crosses the central part of western Guizhou Province shows significant low-velocity anomaly bands,revealing the depth and range of the influence of the Weining-Shuicheng fault zone. Due to the influence of lithology and fluid permeability,the velocity structures at 0km depth in the reservoir area generally show the characteristics of low-velocity and high v_p/v_s, including Jiayan,Pingzhai,Guangzhao and Mamaya reservoir areas. The spatial distribution of relocated earthquakes provides the evidence of the geometric distribution characteristics of a large number of buried faults. Combined with the 3D velocity structure,it is inferred that the seismic activity in this area is related to the fault activation around the reservoir.]]> 2024/1/8 0:00:00 2024/1/8 0:00:00 M6 3/4 occurred near Luoyang mountain in the southeast of Pingshan town,Lingshan county,Guangxi. This event is the largest earthquake that has occurred in the South China continent since documental earthquake records are available. In this study,we collected and organized geological data and the recent research results related to this event. Then,we simulated strong ground motion parameters such as peak ground acceleration and peak ground velocity on each grid points within the area and incorporated the influence of shallow shear wave velocity structure V³⁰_s on the simulation results. Finally,we obtained the strong ground motion distribution of this earthquake and analyzed its characteristics. We compared the simulation results with field survey intensity data and attenuation relationships. The results showed that the simulation results are in good agreement with the survey intensity values and attenuation relationships in terms of overall characteristics and distribution of meizoseismal area. The simulation results of this study can provide a reliable basis for the risk assessment of future earthquake disaster in the region,and the technical methods used in this study can also be applied to rapid regional estimation of seismic intensity,providing assistance for emergency rescue and decision-making command after earthquakes.]]> 2024/1/8 11:35:45 M6.8 earthquake in 2022 is a critical earthquake in the recent Sichuan-Yunnan region. Based on the coseismic rupture model obtained from seismic wave and the Okubo planar rectangular elastic dislocation theory,we simulated the coseismic gravity changes,vertical and horizontal displacements caused by the Luding M6.8 earthquake. The results show that:① The coseismic gravity change image has a high and low four-quadrant symmetrical feature with the fault as the boundary,which is consistent with the pre-seismic(September 2019 to September 2020)measured gravity change image and the left-lateral strike-slip feature of the fault,indicating that the seismic precursor process is related with the lock in shearing force model. ② In the far-field region,the coseismic vertical displacement pattern exhibits similarity to the gravity anomaly pattern. The effect of density variation induced by fault slip surpasses the impact of surface vertical displacement in this context. In contrast,the surface vertical displacement in the near-field exerts a more pronounced influence compared to the density variation effect,demonstrating a negative correlation between them. ③ The coseismic horizontal deformation image has a symmetrical four-quadrant feature,which is consistent with the deformation characteristics by GNSS measurements and InSAR results. These results provide a basis for explaining the gravity and deformation observation results before and after the earthquake,and help us to understand the mechanism of strong earthquake generation,especially for the further improvement of the locked shear model.]]> 2024/1/8 11:35:45 M_S6.9 earthquake in Qinghai Province was compared with the spatial distribution of the coseismic deformation of the Menyuan earthquake extracted by the post-earthquake InSAR technique. The results show that the pre-earthquake infrared radiation enhancement area is basically consistent with the InSAR coseismic rupture deformation area,and the expansion forms are basically similar(the coseismic rupture deformation area is distributed inside the infrared radiation anomaly area). In terms of the spatial distribution of OLR nationwide before the earthquake,only the area of Delingha-Xining-Wuwei has a dumbbell-shaped OLR thermal radiation enhancement area,which is distributed in the near west-east direction,and the spatial recognizability is high. The spatiotemporal evolution process of OLR anomalies follows the thermal anomaly law during rock stress loading and fracture,suggesting that the thermal anomaly changes are related to stress changes. The coseismic deformation extracted by InSAR is mainly located in the intersection of the Sunan-Qilian fault,the Toleshan fault and the Lenglongling fault. The InSAR coseismic deformation results reveal that the surface deformation is mainly in the horizontal direction,and the fault movement has typical strike-slip deformation characteristics. InSAR coseismic deformation results provide referenced geological entity monitoring evidence for infrared remote sensing to reflect seismic deformation,and verify that the radiation enhancement anomaly before the Menyuan earthquake is a remote sensing physical parameter reflection of changes in seismic tectonic stress intensity.]]> 2024/1/8 0:00:00 M_L,M_WP and m_B are commonly used methods of magnitude measurement in automatic earthquake rapid reports. In order to analyze the accuracy of these three methods at different times and demonstrate the reasons of deviations,we simulated the quasi-real-time determination process of the magnitude of the M6.4 earthquake in Jiashi,Xinjiang(January 19,2020)and the moderate-strong earthquake swarm in Yangbi,Yunnan(May 21,2021). By calculating the M_L,M_WP and m_B  magnitudes of 56 earthquake events with M4.5 and above occurred in mainland China from January 1,2020 to July 31,2022,we analyze the stability of these three methods in the determination of moderate-strong earthquake magnitude,after comparing their own benefits and applicability study in different magnitude section. Our results showed that:① Using the conversion relationship converting M_L to M is an important reason for the large deviation. M_L should not be converted,and its value can be directly used as the published magnitude of the automatic quick reports in moderate and strong earthquake events;② For densely occurring earthquake swarms,M_WP and m_B are easily affected by the previous coda wave or long-period signal,resulting in large magnitude and large deviation,so it is not suitable to be used as the magnitude of the automatic rapid reports,but M_L is better;③ In the 4.5～5.5 magnitude range,M_L should be used to measure the magnitude;in the 5.5～6.5 magnitude range,both M_WP or m_B  are good,but M_WP is more stable and time-saving for the earthquakes. For magnitudes above 6.5,M_WP has the better effect and should be applied.]]> 2024/1/8 11:35:45 M_S6.0 earthquake in June 2019,which has been brought wide attention of society and scientific researchers. In this study,we used the double-difference method to relocate the earthquakes within one year before and after the M_S6.0 earthquake. Further,we applied the gCAP waveform fitting method to obtain the focal mechanism solution of 14 earthquakes with M_S>4.0. The spatial distribution characteristics of seismic activities in Changning area was comprehensively analyzed,and the following main understandings were obtained:① The seismogenic structure of the M_S6.0 earthquake in 2019 was the high-dip thrust fault with NW direction in the Changning anticline,and the focal depth of the seismic sequence was deep in the west and shallow in the east,indicating the reactivation of the pre-existing fault in NW direction. ② The frequency of seismic activity in the Jianwu anticline area in the south is relatively higher and shows the characteristics of cluster distribution,which is speculated to be closely related to shale gas exploitation activities. ③ The difference of seismic activity between the north and the south of Changning area is controlled by the change of the direction of the local stress field. The historical salt mining in the north and shale gas mining in the south,as well as the horizontal difference of the physical properties of rock medium directly affect the spatial pattern of seismic distribution.]]> 2024/1/8 11:35:45 M_S5.3 earthquake occurred in Ningqiang county,Hanzhong city,Shaanxi Province. The earthquake depth given by different institutions are somewhat different. Based on the regional velocity model,the focal depth of this earthquake is calculated in this paper in order to confirm the depth result. Firstly,the focal mechanism solution of the earthquake is obtained by inversion by using the CAP method,and then the focal depth is further determined by using the Rayleigh surface wave amplitude spectrum and the error function of the CAP method. The calculation results show that the focal depth of the Ningqiang M_S5.3 earthquake obtained by the CAP method is about 12km,while that of the Rayleigh surface wave amplitude spectrum is 13km. Combining with the above two methods,it is finally determined that the focal depth of the Ningqiang M_S5.3 earthquake is about 13km,which indicates that this earthquake occurred at the upper crust.]]> 2024/1/8 0:00:00 2,and the total area of Ⅶ and above is about 1694km².]]> 2024/1/8 11:35:45 2024/1/8 11:35:45 2024/1/8 11:35:45 2024/1/8 11:35:45