Abstract:Through on-site investigations and data collection,the seismic hazard risk assessment of school buildings in Cixian County,Handan City,Hebei Province,was conducted in accordance with the Technical Specification for Seismic Hazard Risk Classification of Buildings and Structures(FXPC/DZ P-03).Based on the evaluation results and causal analysis,targeted earthquake disaster prevention and mitigation strategies were proposed for school buildings in the region.These strategies aim to enhance the seismic resistance capacity of school infrastructure and reduce potential losses caused by future seismic events.

Abstract:By analyzing the spatial correspondence between known geothermal springs(wells)in the Hebei Province section of Inner Mongolia Axis region and the surrounding areas with respect to geological,geophysical,and geochemical anomalies,this study summarizes the distribution patterns of geothermal resources.Utilizing regional hydrogeology and geophysical and geochemical exploration data,along with existing geothermal information,the study delineates prospective geothermal areas,thereby enhancing the accuracy of geothermal resource prediction.This research provides a comprehensive evaluation of the potential levels of the predicted areas from various professional perspectives,making geothermal exploration efforts more targeted and effectively improving the efficiency of geothermal exploration in the region.The findings have promising application prospects.

Abstract:Based on field investigations,the geological characteristics of the Taihang Mountain Inner Fault are summarized.Its formation mechanism and evolutionary process are analyzed.The geodynamic system of this fault is explored from four perspectives:regional major faults,metamorphic core complexes,basin-range tectonic coupling,and large rivers traversing basin-range regions.Potential geological hazards associated with the fault are assessed.Key findings include:(1)The Taihang Mountain Inner Fault comprises a broad fracture zone formed by a series of secondary faults developed in Paleozoic limestone;(2)The four dimensions constitute an integrated system;(3)While the fault is unlikely to generate seismic hazards,it may pose risks to engineering constructions crossing the fault zone.

Abstract:Taking the Badong section of the Three Gorges Reservoir(30.98°N～31.17°N,110.09°E～110.55°E)as the study area,this study analyzed waveform data from 45 earthquakes with ML≥2.5 recorded between 2013 and 2018 by 22 sub-stations of the Three Gorges Digital Telemetry Seismic Monitoring Network.Focal mechanism solutions were determined using the multi-station P-wave first-motion polarity method,and normal stress inversion of the focal mechanisms was conducted using the MSATSI software with a damped regional stress inversion approach.The results show that:① The 45 ML≥2.5 earthquakes in the Badong reservoir section were predominantly distributed along the Yangtze River,with strike-slip mechanisms dominating the focal solutions;② The maximum principal compressive(σ1)and extensional(σ3)stress axes exhibited spatially heterogeneous orientations:in the eastern Dongrangkou area,σ1 axes trends from NWW to nearly EW,while σ3 axes is aligned approximately NS;in the western Dongrangkou area,σ1 axes is oriented NE,and σ3 axes trends NW;③ Focal mechanisms of five ML≥4.0 earthquakes showed good consistency with the annual stress field inversion results;④ Most of the 45 ML≥2.5 earthquakes occurred during high-and low-water-level stages of the reservoir,suggesting a statistically significant temporal clustering pattern.

Abstract:Based on 834 focal mechanism solutions of the 2023 MW7.7 and MW7.6 earthquakes in southeastern Turkey,this study systematically investigated the tectonic stress field in the seismic source regions and adjacent areas using the damped regional stress tensor inversion method with partitioned grid units.The results indicate that:① The optimal inversion grid size is 0.6°×0.6°.② The predominant orientation of the maximum principal stress axis shows SSW-NNE direction,while the minimum principal stress axis predominantly aligns with EES-NWW direction.Spatially,the maximum principal stress axis exhibits clockwise deflection from south to north and west to east,whereas the minimum principal stress axis demonstrates counterclockwise deflection from north to south and east to west.The stress shape factor R-value is less than 0.5.③ The stress field in the MW7.7 earthquake source region is dominated by horizontal compressive stress accompanied by significant vertical tectonic deformation,while the stress field in the MW7.6 earthquake source region exhibits strong compression combined with pronounced shear deformation.

Abstract:The first report processing results of Yunnan earthquake early warning Jopens Earthquake Early Warning(JEEW)system from April 2020 to May 2024 and Earthquake Early Warning(EEW)system from July 2020 to May 2024 were selected to compare with the national unified cataloging results.In addition,the output results of the M 5.2 earthquake in Baoshan,Yunnan,on May 2,2023,were analyzed.The results are as follows.First,the average initial report time of JEEW system is 8.4 s,while that of EEW system is 8.3 s.There is little difference in early warning timeliness.Second,the processing results of the two early warning systems for the time of occurrence and epicenter location of earthquakes in Yunnan Province are stable and reliable.However,the accuracy of EEW system is lower than that of JEEW system,especially for earthquakes outside Yunnan Province.Third,the deviation of the early warning magnitude measured by the two early warning systems for earthquakes with 3.0≤M＜6.0 is small,but for earthquakes with M＜3.0 and M≥6.0,the determination of the early warning magnitude has great uncertainty.Fourth,the initial reporting time of the two early warning systems for the M5.2 earthquake in Baoshan,Yunnan is basically the same.The results of earthquake occurrence time,epicenter location and magnitude output are stable and reliable.By analyzing the reasons for the deviation in the processing results,reasonable suggestions were proposed for the Yunnan earthquake early warning system,providing a fundamental support for the subsequent optimization and improvement of the system.

Abstract:In order to further study the background noise level and observation data quality of deep well seismic observation system,this paper uses Fourier transform to analyze the acceleration PSD probability density function,characteristic analysis of RMS value in the 1-20 Hz frequency band and teleseismic and near-earthquake events of Chifeng Earthquake Monitoring Center Station,Ailshan Earthquake Monitoring Station and Erenhot Earthquake Monitoring Station.The results show that the temperature exerts a significant influence on the background noise within the secondary microseismic frequency band ranging from 100 s to 0.1 Hz.When the temperature is low,the background noise is relatively large.The average RMS values of CHF,ARS and RLT monitoring stations in the 1-20 Hz frequency band in three directions are 4.4e-008m/s、1.79e-008m/s and 2.13e-008m/s,respectively.The RMS values of ARS and RLT monitoring stations have reached the noise level of class I environment,the RMS value of CHF monitoring station belongs to the noise level of class II environment.The ARS monitoring station and the RLT monitoring station record seismic waveforms over a wide range of frequencies with larger amplitude and wider dynamic range.The frequency corresponding to the maximum amplitude of the teleseismic earthquake tends to move to higher frequencies as the epicenter distance increases.The frequency range and amplitude of the recorded seismic waveforms at the three monitoring stations are directly related to the epicenter distance and background noise.

Abstract:This article takes the Zizhi tunnel project as the research object and uses multiple technical methods such as on-site surveying,drilling,in-situ testing and indoor experiments to analyze the engineering geological conditions along the project area,including engineering rock group division,physical and mechanical properties of rock and soil mass,and tunnel stability.The results show that the geohazards of the Zizhi tunnel project are mainly the result of the combined effects of various geological factors such as lithology,groundwater,structural planes and karst.When the tunnel is excavated into fine sand and sandstone formations,the stability of the surrounding rock undergoes significant changes due to weathering,structural planes and fault activity.Especially for fully weathered fine sandstone,its mechanical properties have significantly deteriorated,and the maximum compressive strength of the rock has decreased by about 50%,resulting in a deterioration of the stability of the surrounding rock.Therefore,for areas with dense development of structural planes,advance support should be provided during construction,and tunnel excavation should be carried out with short footage and timely strengthening of lining and drainage measures.

Abstract:By drawing on the development model of public science,this paper constructs a school disaster science education model with the core of"guiding teachers and students to participate widely".It also puts forward suggestions such as improving the working mechanism,strengthening facility guarantees,enhancing infrastructure construction,improving education models,supporting industrial development,broadening education channels,strengthening cultural construction,creating a strong atmosphere,enriching educational forms,and achieving precise education.These suggestions provide useful references for strengthening disaster science education in schools in the new era of China.

Abstract:The fault plane solution of the double-couple mechanism has two node planes,which is usually represented to be the seismogenic fault planes.However,the actual seismogenic plane can only be obtained by combining the surface faults and the dominant distribution direction of aftershock sequence.In this study,the instability coefficient of fault plane is used to quantitatively evaluate the best seismogenic plane of the two nodes in the focal mechanism solution.Through the study of moderate earthquakes in the Tangshan fault zone,the seismogenic fault plane is well obtained,and the direction is consistent with the seismic sequence.Furthermore,this study discusses the segmentation characteristics of the Tangshan fault zone.The results show that the Tangshan fault zone is not a single fault plane,but a combination of different strike faults.The fault geometry obtained in this study reveals the complexity of the seismogenic environment of the Tangshan fault zone.

Abstract:Zhangjiakou-Penglai fault is an important NW-trend seismic tectonic zone in north China.According to the study in recent years,we divided the fault into 4 segments:Zhangbei-Nankou segment,Nankou-Ninghe segment,Bohai segment and Penglai-Yantai　segment.Each segment has its own geometrical kinematic character.The relation between NW-trend and NE-trend faults in the zone is discussed.