The epicenter of the Luxian M_(S)6.0 earthquake on September 16,2021,was located in the southern Sichuan Basin,which is a historically seismically quiescent area.In recent years,the frequency of earthquakes has increa...The epicenter of the Luxian M_(S)6.0 earthquake on September 16,2021,was located in the southern Sichuan Basin,which is a historically seismically quiescent area.In recent years,the frequency of earthquakes has increased with the large-scale exploitation of shale gas.No evident surface fractures or seismic faults were observed after the Luxian earthquake.Based on high-quality data recorded by a dense seismic array composed of 70 portable stations with an average spacing of 2-3 km,a highresolution seismic catalog was constructed for 7 days before and 36 days after the M_(S)6.0 earthquake using LOC-FLOW,an effective workflow of phase picking,phase association,and earthquake location.Based on the new earthquake catalog,four earthquake clusters that occurred within the Yujiasi Syncline during this period were identified.Among them,the M_(S)6.0 main earthquake sequence had a NW-SE trend and inclined towards the SW,with a length of approximately 8 km and width of 5 km.The M_(S)6.0 earthquake sequence only appeared after the mainshock.The other three clusters were located in the northeast direction of the M_(S)6.0 earthquake sequence,all of which were NE-SW trending strips and had no evident direct correlation with the M_(S)6.0 mainshock.The focal depth was concentrated in the range of 2-7 km.Based on the seismic sequence profile and structural background,the M_(S)6.0 seismic structure may be a blind buried fault zone with a NW strike composed of multiple small conjugate faults with NE and SW dip.The fault was not exposed on the surface and was related to the detachment structure in the deep part of the Sichuan Basin.展开更多
An Ms 6.4 earthquake occurred in Yangbi,Yunnan,China on May 21,2021,which has obvious foreshock activity and abundant aftershocks.Based on the seismic observation data recorded by the Yunnan Seismic Network three days...An Ms 6.4 earthquake occurred in Yangbi,Yunnan,China on May 21,2021,which has obvious foreshock activity and abundant aftershocks.Based on the seismic observation data recorded by the Yunnan Seismic Network three days before and seven days after the mainshock,a doubledifference location method was used to relocate 2133 earthquakes of the Yangbi sequence.Aftershocks are mostly distributed to the southeast of the mainshock in a unilateral rupture pattern.This sequence exhibits a SE-trending linear alignment with a length of about 25 km,and most of the focal depth is above 12 km.Integrated with the seismic distribution and focal mechanism results,we infer that the strike of the seismogenic fault is about 140°,and dipping to the SW.The fault structure revealed by the seismic sequence is complex,with the NW segment exhibiting a steep dip and relatively simple structure of strike-slip rupture and the SE segment consisting of several branching ruptures.The Yangbi Earthquake is a typical foreshock-mainshock-aftershock sequence,and the mainshock is likely triggered by the largest foreshock.This earthquake occurred in the boundary between high-and lowvelocity anomalous zone,where is susceptible to generate large earthquakes.展开更多
The geomagnetic data recorded by Kashi and Jinghai observatories in China were analyzed with improved polarization method. We compared the result around 0.01 Hz which is thought to be useful to detect the ULF anomaly ...The geomagnetic data recorded by Kashi and Jinghai observatories in China were analyzed with improved polarization method. We compared the result around 0.01 Hz which is thought to be useful to detect the ULF anomaly with the result around 0.1 Hz which was inferred from the earthquake depth according to the skin effect, and found that 0.1 Hz is more proper to detect the ULF anomaly for both earthquakes studied in this paper.展开更多
We present a high-resolution seismic catalog for the 2021 M_(S)6.4/M_(W)6.1 Yangbi sequence.The catalog has a time range of 2021-05-01 to 2021-05-28,and contains~8,000 well located events.It captures the features of t...We present a high-resolution seismic catalog for the 2021 M_(S)6.4/M_(W)6.1 Yangbi sequence.The catalog has a time range of 2021-05-01 to 2021-05-28,and contains~8,000 well located events.It captures the features of the whole foreshock sequence and the early aftershocks.We designed a detection strategy incorporating both an artificial intelligent(AI)picker and a matched filter algorithm.Here,we adopt a hybrid AI method incorporating convolutional and recurrent neural network(CNN&RNN)for event detection and phase picking respectively(i.e.CERP),a light-weight AI picker that can be trained with small volume of data.CERP is first trained with detections from a STA/LTA and Kurtosis-based method called PAL,and then construct a rather complete template set of~4,000 events.Finally,the matched filter algorithm MESS augments the initial detections and measures differential travel times with cross-correlation,which finally results in precise relocation.This process gives 9,026 detections,among which 7,943 events can be well relocated.The catalog shows as expected power-law distribution of frequency magnitude and reveals detailed pattern of seismicity evolution.The main features are:(1)the foreshock sequence images simple fault geometry with consistent strike,but also show a variable event depth along strike;(2)the mainshock ruptures the same fault of the foreshock sequence and activate conjugate faults further to the southeast;(3)complex seismicity are developed in the post-seismic period,indicating complex triggering mechanisms.Thus,our catalog provides a reliable basis for further investigations,such as b-value studies,rupture process,and triggering relations.展开更多
Based on the case studies and statistical analysis of earthquake-related ionospheric disturbances mainly from DEMETER satellite, ground-based GPS and ionosounding data, this paper summarizes the statisw tical characte...Based on the case studies and statistical analysis of earthquake-related ionospheric disturbances mainly from DEMETER satellite, ground-based GPS and ionosounding data, this paper summarizes the statisw tical characteristics of earthquake-related ionospheric disturbances, including electromagnetic emissions, plasma perturbations and variation of energetic particle flux. According to the main results done by Chinese scientists, fusing with the existed study from global researches, seismo-ionospheric disturbances usually occurred a few days or hours before earthquake occurrence. Paralleling to these case studies, lithosphere-atmosphere-ionosphere （LAI） coupling mechanisms are checked and optimized. A thermo-electric model was proposed to explain the seismo-electromagnetic effects before earthquakes. A propagation model was put forward to explain the electromagnetic waves into the ionosphere. According to the requirement of earthquake prediction research, China seismo-electromagnetic satellite, the first space-based platform of Chinese earthquake stereoscopic observation system, is proposed and planned to launch at about the end of 2014. It focuses on checking the LAI model and distinguishing earthquake-related ionospheric disturbance. The preliminary design for the satellite will adopt CAST-2000 platform with eight payloads onboard. It is believed that the satellite will work together with the ground monitoring network to improve the capability to capture seismo-electromagnetic information, which is beneficial for earthquake monitoring and prediction researches.展开更多
In this study,we developed a high-resolution(3 arcsec,approximately 90 m)V_(S30) map and associated open-access dataset for the 140 km×200 km region affected by the January 2025 M6.8 Dingri Xizang,China earthquak...In this study,we developed a high-resolution(3 arcsec,approximately 90 m)V_(S30) map and associated open-access dataset for the 140 km×200 km region affected by the January 2025 M6.8 Dingri Xizang,China earthquake.This map provides a significantly finer resolution compared to existing V_(S30) maps,which typically use a 30 arcsec grid.The V_(S30) values were estimated using the Cokriging-based V_(S30) proxy model(SCK model),which integrates V_(S30) measurements as primary constraints and utilizes topographic slope as a secondary parameter.The findings indicate that the V_(S30) values range from 200 to 250 m/s in the sedimentary deposit areas near the earthquake’s epicenter and from 400 to 600 m/s in the surrounding mountainous regions.This study showcases the capability of the SCK model to efficiently generate V_(S30) estimations across various spatial resolutions and demonstrates its effectiveness in producing reliable estimations in data-sparse regions.展开更多
The spatial and temporal slip distribution of the Lushan earthquake was estimated using teleseismic body wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative...The spatial and temporal slip distribution of the Lushan earthquake was estimated using teleseismic body wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized Akaike＇ s Bayesian Information Criterion （ABIC）. The inversion generated the source parameters. Strike, dip and slip were 218°, 39° and 100. 8° ,respectively. A seismic moment （M0） was 2. 1 × 10^20 Nm with a moment magnitude （Mw） of 6. 8, and a source duration was approximately 30 second. The rupture propagated along the dip direction, and the maximum slip occurred at the hypocenter. The maximum slip was approximately 2. 1 m, although this earthquake did not cause an apparent surface rupture. The energy was mainly released within 10 second. In addition, the Lushan earthquake was apparently related to the 2008 Wenchuan earthquake. However, the question of whether it was an aftershock of the Wenchuan earthquake requires further study.展开更多
Stochastic finite-fault simulations are effective for simulating ground motions and are widely used in engineering to determine the impacts of ground motion and develop relevant predictive equations.In this study,the ...Stochastic finite-fault simulations are effective for simulating ground motions and are widely used in engineering to determine the impacts of ground motion and develop relevant predictive equations.In this study,the source,path,and site amplification coefficient of western Sichuan Province,China,and stochastic finite-fault simulations were used to simulate the acceleration time series,Fourier amplitude spectra,and 5%damped response spectra of 28 strong-motion stations with rupture distances within 300 km of the 2022 MS6.8 Luding earthquake.The simulation results of 14 stations at rupture distances of 45-185 km match the observation.However,the simulation results of 3 near-and 6 far-field stations at rupture distances of 12-36 km and 222-286 km,respectively,were obviously deviated from the observations.Simulation results of the near-field stations are larger than the observations at high frequencies(>6 Hz).The discrepancy likely comes from the nonlinear site effect of near-field stations,which reduced the site amplification at high frequencies.Simulation result of the far-field stations is smaller than the observation at frequencies above 1 Hz.As these stations are located close to the Longmenshan Fault Zone(LFZ),thus,we obtained a new quality factor(Q)from data of historical events and stations located around LFZ.Using the new Q value,the discrepancies of the high-frequency simulation results of the far-field stations were corrected.This result indicated that the laterally varying Q values can be used to address the impact of strong crustal lateral heterogeneity on simulation.展开更多
A M_(S)6.8 earthquake occurred on 5th September 2022 in Luding county,Sichuan,China,at 12:52 Beijing Time(4:52 UTC).We complied a dataset of PGA,PGV,and site vS30 of 73 accelerometers and 791 Micro-Electro-Mechanical ...A M_(S)6.8 earthquake occurred on 5th September 2022 in Luding county,Sichuan,China,at 12:52 Beijing Time(4:52 UTC).We complied a dataset of PGA,PGV,and site vS30 of 73 accelerometers and 791 Micro-Electro-Mechanical System(MEMS)sensors within 300 km of the epicenter.The inferred v_(S30)of 820 recording sites were validated.The study results show that:(1)The maximum horizontal PGA and PGV reaches 634.1 Gal and 71.1 cm/s respectively.(2)Over 80%of records are from soil sites.(3)The v_(S30)proxy model of Zhou J et al.(2022)is superior than that of Wald and Allen(2007)and performs well in the study area.The dataset was compiled in a flat file that consists the information of strong-motion instruments,the strong-motion records,and the v_(S30)of the recording sites.The dataset is available at https://www.seismisite.net.展开更多
Since the 1970s, Chinese seismologists have started to conduct the Annual Consultation on the Likelihood of Coming Earthquakes in the Next Year. This approach has unique scientific and practical merits either as an ac...Since the 1970s, Chinese seismologists have started to conduct the Annual Consultation on the Likelihood of Coming Earthquakes in the Next Year. This approach has unique scientific and practical merits either as an active response to the social needs in the situation that earthquake prediction research meets many difficulties, or as a real forward prediction test persistently conducted for 1/3 century. It is a pity that such an approach has not been well-known by international seismological community, and the scientific merits of such an endeavor is sometimes regrettably underestimated.展开更多
On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the ne...On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002~2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of restrictions on the computation environment and condition, e.g., the earthquakes are densely concentrated, selected stations are limited in range, the number of stations in- volved in the computation is larger than 5 and linear fitting features high precision and small error. Under these restrictions, the study shows that vP/vS in and around Wen’an and Tangshan underwent a normal-low-normal proc- ess one year before Wen’an earthquake, vP/vS became obviously low and the low ratio lasted for about one year, meanwhile, little variation of vP/vS was seen in Xingtai, northwest of Beijing, southwest of Beijing, Beijing-Tianjin and Beijing; after the quake, the vP/vS returned normal in Wen’an and Tangshan. Error and stability analysis of the calculated result for vP/vS shows it is convincible that anomaly appeared in and around Wen’an and Tangshan be- fore Wen’an earthquake.展开更多
Investigating spatiotemporal changes in crustal stress associated with major earthquakes has implications for understanding seismogenic processes.However,in individual earthquake cases,the characteristics of the stres...Investigating spatiotemporal changes in crustal stress associated with major earthquakes has implications for understanding seismogenic processes.However,in individual earthquake cases,the characteristics of the stress after it reaches its maximum value are rarely discussed.In this study,we use the 2021 M_S6.4 Yangbi earthquake in Yunnan,China and events of magnitudes M_L≥3.0 occurred in the surrounding area in the previous 11 years to investigate the spatiotemporal evolution of apparent stress.The results indicate that apparent stress began to increase in January 2015 and reached a maximum in January 2020.Apparent stress then remained at a high level until October 2020,after which it declined considerable.We suggest that the stress was in the accumulation stage from January 2015 to January 2020,and entered the meta-instability stage after October 2020.During the meta-instability stage,the zone of decreasing stress expanded continuously and the apparent stress increased around the Yangbi earthquake source region.These features are generally consistent with the results of laboratory rock stress experiments.We propose that apparent stress can be a good indicator for determining whether the stress at a specific location has entered the meta-instability stage and may become the epicenter of an impending strong earthquake.展开更多
The 6 August 2023 M_(W)5.5 Pingyuan earthquake is the largest earthquake in the central North China Plain(NCP)over the past two decades.Due to the thick sedimentary cover,no corresponding active faults have been repor...The 6 August 2023 M_(W)5.5 Pingyuan earthquake is the largest earthquake in the central North China Plain(NCP)over the past two decades.Due to the thick sedimentary cover,no corresponding active faults have been reported yet in the epicenter area.Thus,this earthquake presents a unique opportunity to delve into the buried active faults beneath the NCP.By integrating strong ground motion records,high-precision aftershock sequence relocation,and focal mechanism solutions,we gain insights into the seismotectonics of the Pingyuan earthquake.The aftershocks are clustered at depths ranging from 15 to 20 km and delineate a NE-SW trend,consistent with the distribution of ground motion records.A NE-SW nodal plane(226°)of the focal mechanism solutions is also derived from regional waveform inversion,suggesting that the mainshock was dominated by strike-slip motion with minor normal faulting component.Integrating regional geological data,we propose that an unrecognized fault between the NE-SW trending Gaotang and Lingxian-Yangxin faults is the seismogenic fault of this event.Based on the S-wave velocity structure beneath the NCP,this fault probably extends into the lower crust with a high angle.Considering the tectonic regime and stress state,we speculate that the interplay of shear strain between the Amurian and South China blocks and the hot upwelling magma from the subducted paleo Pacific flat slab significantly contributed to the generation of the Pingyuan earthquake.展开更多
1.Introduction On December 18,2023,a M6.2 earthquake struck central China with epicenter at Jishishan,Gansu(35.70°N,102.79°E).In the USGS Latest Earthquake platform,the event was identified as M_(W)5.9,35.74...1.Introduction On December 18,2023,a M6.2 earthquake struck central China with epicenter at Jishishan,Gansu(35.70°N,102.79°E).In the USGS Latest Earthquake platform,the event was identified as M_(W)5.9,35.743°N,102.827°E,labeled 37 km WNW of Linxia Chengguanzhen,China.This study presents an open-access dataset comprising PGA and PGV records of the main-shock from 202accelerometers and 539 Micro-Electro-Mechanical System(MEMS)sensors within two arcdegrees of the epicenter.展开更多
For city planning and reducing potential earthquake risk,it’s necessary to detect the information of the buried faults in an urban area especially,including the location and activities.An integrated technique with ge...For city planning and reducing potential earthquake risk,it’s necessary to detect the information of the buried faults in an urban area especially,including the location and activities.An integrated technique with geophysical and geological methods,including the shallow seismic reflection profile,electrical resistivity measurement,geologic borehole section,and exploration trench,was used to detect the Chengnanhe fault,which is one of the two main faults passing through the Weihai urban area in Shandong province,China.The results show that it is a normal fault striking with E-W direction,and it is relatively inactive and stable.By using the thermoluminescence(TL)dating,we found that the Chengnanhe fault initiated in mid-Pleistocene and there was no offset after late Pleistocene.Such an integrated technique with multiple geological and geophysical methods provides a significant assessment of earthquake risk for city planning in urban areas.展开更多
Paleoearthquake research represents an essential method for determining recurrence intervals oflarge earthquakes.Reasonable determination of the average recurrence interval and coefficient of variationprovides a cruci...Paleoearthquake research represents an essential method for determining recurrence intervals oflarge earthquakes.Reasonable determination of the average recurrence interval and coefficient of variationprovides a crucial basis for the analysis of the recurrence characteristics of strong earthquakes on intraplatefaults in Chinese mainland.Paleoearthquake data from 145 fault segments of 93 well-studied faults in MainlandChina were collected,organized,and analyzed to discuss the rational estimation of the average recurrenceinterval and coefficient of variation of a strong earthquake occurrence probability model.First,differencesin structural environments were used as a basis to investigate the spatial distribution characteristics of theaverage recurrence intervals of strong earthquakes.The results indicate significant variations in the recurrenceperiods of strong earthquakes in the Sichuan–Yunnan,Xinjiang,North China,and northeastern Qinghai-Tibet Plateau structure zones.The Sichuan–Yunnan structure zone exhibited the shortest average recurrence intervalfor strong earthquakes,which was mainly distributed between 100 and 2000 years,and a relatively high sliprate.The Xinjiang structure zone attained a relatively balanced recurrence interval frequency distribution of1000–4500 years and a moderate slip rate.The North China structure zone showed the lowest slip rate,withthe strong earthquake recurrence interval mainly concentrated between 1000 and 4000 years.The northeastern Qinghai-Tibet Plateau structure zone presented two main frequency peaks in the strong earthquake recurrenceintervals between 1000–3000 years and 3000–5000 years and a relatively high slip rate.The slip rate is a keyfactor influencing the recurrence interval of strong earthquakes,and active faults with high slip rates showshort recurrence intervals.Furthermore,the relationship between fault slip rate,fault type,and the averagerecurrence interval of strong earthquakes was examined.The results indicate a good logarithmic linearrelationship between the fault slip rate and the average recurrence interval of large earthquakes—the higherthe slip rate,the shorter the recurrence interval of strong earthquakes.Fault type also showed a relation to theaverage recurrence interval,with the intervals for various types of active faults gradually increasing in theorder of strike-slip,normal,reverse strike-slip,reverse,and normal strike-slip faults.Second,we calculated theproportions of active faults and various fault types in each structure zone that had a coefficient of variation inrecurrence intervals less than 0.4.The findings reveal that the occurrence of strong earthquakes on most activefaults in Chinese mainland satisfies a quasiperiodic model.The general coefficient of variation across differentstructure zones and fault types ranges between 0.36 and 0.44,which indicates the nonsignificant difference inthe degree of variability in the periodicity of strong earthquake occurrence across various structural zones andfault types.展开更多
The Low Earth Orbit(LEO)geomagnetic satellites provide a large number of high-precision measurements,which are crucial for researching the Secular Variation(SV)of the geomagnetic field.We employ the combined constella...The Low Earth Orbit(LEO)geomagnetic satellites provide a large number of high-precision measurements,which are crucial for researching the Secular Variation(SV)of the geomagnetic field.We employ the combined constellation data from the Chinese Seismo-Electromagnet Satellite(CSES)and Swarm satellites to extract the SV in China and surrounding areas,based on the Geomagnetic Virtual Observatory(GVO)method.On this basis,we have developed two GVO products:the core field,and the SV series.The accuracies of these products are assessed using ground observatories measurements and geomagnetic field model.Moreover,the results indicate that the GVO products align well with the series from ground observatories and the CHAOS model.The majority of root-mean-square deviation(RMSE)values of the core field series are less than 5 nT,consistent with the INTERMAGNET standards for quasi-definitive data.In the GVO core field series,the maximum accuracy of one-month and four-month intervals are 2.24 nT and 1.16 nT,respectively.In the GVO SV series,the maximum accuracy of one-month and four-month intervals are 2.03 nT/yr and 1.36 nT/yr,respectively.The GVO SV series effectively capture geomagnetic jerks without losing temporal resolution comparing with the recording of ground observatories.We demonstrate that the GVO method serves as an effective and precise tool for extracting SV information of geomagnetic fields.In the GVO products,the RMSE of the horizontal component exceeds that of the vertical component,and the magnitude of RMSE deviation correlates with solar activity levels.With more and more geomagnetic satellites in orbit,we wish to use multi-constellation magnetic satellite data to assess the geomagnetic field more accurately.展开更多
Local strong seismic activity shows the potential to closely follow a renewal process,which is inconsistent with the overall seismic activity that aligns with the Poisson process.Given that existing methods for synthe...Local strong seismic activity shows the potential to closely follow a renewal process,which is inconsistent with the overall seismic activity that aligns with the Poisson process.Given that existing methods for synthesizing stochastic seismic event sets cannot control local seismic activity,a method based on Monte Carlo simulations has been developed for synthesizing random seismic event sets where local strong earthquakes satisfy the renewal process.This method can synthesize seismic activities in a statistical area where the overall activity conforms to the Poisson process and the major seismic activities in local potential sources or faults follow the renewal process.This paper presents long-and short-scale approaches.The long-scale earthquake catalogs are suitable for reflecting the sequential characteristics of seismic activities.Meanwhile,the short-scale catalogs focus on the impacts of specific earthquake events within a group for a detailed understanding of hazards under certain conditions,making them suitable for studies on specific earthquake sequences and geological areas or situations requiring high temporal resolution.In the applications of shortscale sequences,we find that the equivalent occurrence rate method may overestimate the seismic hazard.This synthesis method for earthquake catalogs can simulate realistic seismic activities,thereby enhancing the accuracy of hazard analysis results and is suitable for seismic hazard analysis and earthquake insurance rate setting.展开更多
The spatial autocorrelation(SPAC)(also known as the Aki’s spectral method)of ambient seismic noise has been widely adopted in surface wave phase velocity extraction.In two-dimensional cases,the surface wave velocity ...The spatial autocorrelation(SPAC)(also known as the Aki’s spectral method)of ambient seismic noise has been widely adopted in surface wave phase velocity extraction.In two-dimensional cases,the surface wave velocity can be calculated by fitting the SPAC coefficients with the zero-order Bessel function of the first kind or using the zeros of the Aki’s spectrum.This method has also been extended to active-source records.This study examined the application of the zeros of Aki’s spectra on active-source records using theoretical analysis and numerical simulation.We show that the zeros of the Aki’s spectrum should be associated with the zeros of the cosine function instead of the zeros of the zero-order Bessel function when extracting the phase velocity of the surface wave,considering the data acquisition and processing of the active-source records.The proposed method was then applied to the active-source data from methane explosion experiments collected using a dense array in Tongzhou,the subcenter of Beijing,for extracting the phase velocity of Rayleigh wave.The extracted dispersion curves were integrated with those obtained by beamforming the ambient noise to yield broadband dispersion curves at 0.3–6 Hz.This provides insightful results at high frequencies,at which less information can be obtained through the passive-source beamforming.The combing phase velocities from active-source with those obtained from ambient noise provide a better constrain on the shallow structure.Based on the combined fundamental mode dispersion curves at 28 excitation points,the S-wave velocity structure below the dense array is obtained by depth inversion.Due to the constraints imposed by the high-frequency information from active source,the estimated vS30 are more reliable and can be used to the site classification.展开更多
Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure.This study employs historical data from the M 7.5 earthquake that occurre...Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure.This study employs historical data from the M 7.5 earthquake that occurred in 1850 to simulate the impacts of a M 7.5 event on hydropower stations located in proximity to Xichang.Key factors taken into account in the simulation of seismic motion encompass uncertainties,mixed-source models,and the placement of asperities.Through these simulations,we acquired the peak ground acceleration(PGA),acceleration time histories,and acceleration response spectra for the hydropower facilities affected by the earthquake.To perform a comprehensive analysis,we utilized a multi-scenario stochastic finite fault simulation method to estimate parameters including the minimum,average,and maximum values of PGA and pseudo-spectral acceleration(PSA)response spectra.Additionally,we assessed the 50^(th),84^(th),and 95^(th)percentiles values of the peak ground acceleration and pseudo-spectral acceleration response spectra.The simulation results also include peak ground acceleration field maps and peak ground velocity(PGV)field maps and intensity distribution maps pertaining to the earthquake.The findings demonstrate that the intensity maps produced through the stochastic finite fault method closely correspond with the intensity contour maps published of historical seismic records.These findings offer significant insights for the seismic safety evaluation and design of the specified hydropower stations.Moreover,this multi-scenario methodology can be effectively utilized for other critical infrastructure projects to derive dependable seismic motion parameters.展开更多
基金supported by Fundamental Research Funds from the Institute of Geophysics,China Earthquake Administration(Nos.DQJB22B26 and DQJB22B19)the National Key Research and Development Program of China(No.2020YFA0710603-02).
文摘The epicenter of the Luxian M_(S)6.0 earthquake on September 16,2021,was located in the southern Sichuan Basin,which is a historically seismically quiescent area.In recent years,the frequency of earthquakes has increased with the large-scale exploitation of shale gas.No evident surface fractures or seismic faults were observed after the Luxian earthquake.Based on high-quality data recorded by a dense seismic array composed of 70 portable stations with an average spacing of 2-3 km,a highresolution seismic catalog was constructed for 7 days before and 36 days after the M_(S)6.0 earthquake using LOC-FLOW,an effective workflow of phase picking,phase association,and earthquake location.Based on the new earthquake catalog,four earthquake clusters that occurred within the Yujiasi Syncline during this period were identified.Among them,the M_(S)6.0 main earthquake sequence had a NW-SE trend and inclined towards the SW,with a length of approximately 8 km and width of 5 km.The M_(S)6.0 earthquake sequence only appeared after the mainshock.The other three clusters were located in the northeast direction of the M_(S)6.0 earthquake sequence,all of which were NE-SW trending strips and had no evident direct correlation with the M_(S)6.0 mainshock.The focal depth was concentrated in the range of 2-7 km.Based on the seismic sequence profile and structural background,the M_(S)6.0 seismic structure may be a blind buried fault zone with a NW strike composed of multiple small conjugate faults with NE and SW dip.The fault was not exposed on the surface and was related to the detachment structure in the deep part of the Sichuan Basin.
基金financially supported by National Science Foundation of China(No.41774067)the National Key R&D Program of China(No.2018YFC1503400)+1 种基金the Special Fund of the Institute of GeophysicsChina Earthquake Administration(No.DQJB20X07)。
文摘An Ms 6.4 earthquake occurred in Yangbi,Yunnan,China on May 21,2021,which has obvious foreshock activity and abundant aftershocks.Based on the seismic observation data recorded by the Yunnan Seismic Network three days before and seven days after the mainshock,a doubledifference location method was used to relocate 2133 earthquakes of the Yangbi sequence.Aftershocks are mostly distributed to the southeast of the mainshock in a unilateral rupture pattern.This sequence exhibits a SE-trending linear alignment with a length of about 25 km,and most of the focal depth is above 12 km.Integrated with the seismic distribution and focal mechanism results,we infer that the strike of the seismogenic fault is about 140°,and dipping to the SW.The fault structure revealed by the seismic sequence is complex,with the NW segment exhibiting a steep dip and relatively simple structure of strike-slip rupture and the SE segment consisting of several branching ruptures.The Yangbi Earthquake is a typical foreshock-mainshock-aftershock sequence,and the mainshock is likely triggered by the largest foreshock.This earthquake occurred in the boundary between high-and lowvelocity anomalous zone,where is susceptible to generate large earthquakes.
基金financially supported by the Special Project for Earthquake Research(200708033)
文摘The geomagnetic data recorded by Kashi and Jinghai observatories in China were analyzed with improved polarization method. We compared the result around 0.01 Hz which is thought to be useful to detect the ULF anomaly with the result around 0.1 Hz which was inferred from the earthquake depth according to the skin effect, and found that 0.1 Hz is more proper to detect the ULF anomaly for both earthquakes studied in this paper.
基金supported jointly by National Key R&D Program of China(No.2018YFC1503400)National Natural Science Foundation of China projects(Nos.41774067,U2039204,and 42074046)+2 种基金Science for Earthquake Resilience(No.XH20082Y)US National Science Foundation(No.1941719)University of California at Riverside.
文摘We present a high-resolution seismic catalog for the 2021 M_(S)6.4/M_(W)6.1 Yangbi sequence.The catalog has a time range of 2021-05-01 to 2021-05-28,and contains~8,000 well located events.It captures the features of the whole foreshock sequence and the early aftershocks.We designed a detection strategy incorporating both an artificial intelligent(AI)picker and a matched filter algorithm.Here,we adopt a hybrid AI method incorporating convolutional and recurrent neural network(CNN&RNN)for event detection and phase picking respectively(i.e.CERP),a light-weight AI picker that can be trained with small volume of data.CERP is first trained with detections from a STA/LTA and Kurtosis-based method called PAL,and then construct a rather complete template set of~4,000 events.Finally,the matched filter algorithm MESS augments the initial detections and measures differential travel times with cross-correlation,which finally results in precise relocation.This process gives 9,026 detections,among which 7,943 events can be well relocated.The catalog shows as expected power-law distribution of frequency magnitude and reveals detailed pattern of seismicity evolution.The main features are:(1)the foreshock sequence images simple fault geometry with consistent strike,but also show a variable event depth along strike;(2)the mainshock ruptures the same fault of the foreshock sequence and activate conjugate faults further to the southeast;(3)complex seismicity are developed in the post-seismic period,indicating complex triggering mechanisms.Thus,our catalog provides a reliable basis for further investigations,such as b-value studies,rupture process,and triggering relations.
基金funded by National Key Technology R&D Program in the 11th Five Year Plan of China (2008BAC35B00)the international cooperation project(2009DFA21480)
文摘Based on the case studies and statistical analysis of earthquake-related ionospheric disturbances mainly from DEMETER satellite, ground-based GPS and ionosounding data, this paper summarizes the statisw tical characteristics of earthquake-related ionospheric disturbances, including electromagnetic emissions, plasma perturbations and variation of energetic particle flux. According to the main results done by Chinese scientists, fusing with the existed study from global researches, seismo-ionospheric disturbances usually occurred a few days or hours before earthquake occurrence. Paralleling to these case studies, lithosphere-atmosphere-ionosphere （LAI） coupling mechanisms are checked and optimized. A thermo-electric model was proposed to explain the seismo-electromagnetic effects before earthquakes. A propagation model was put forward to explain the electromagnetic waves into the ionosphere. According to the requirement of earthquake prediction research, China seismo-electromagnetic satellite, the first space-based platform of Chinese earthquake stereoscopic observation system, is proposed and planned to launch at about the end of 2014. It focuses on checking the LAI model and distinguishing earthquake-related ionospheric disturbance. The preliminary design for the satellite will adopt CAST-2000 platform with eight payloads onboard. It is believed that the satellite will work together with the ground monitoring network to improve the capability to capture seismo-electromagnetic information, which is beneficial for earthquake monitoring and prediction researches.
基金supported by the National Natural Science Foundation of China(No.42120104002).
文摘In this study,we developed a high-resolution(3 arcsec,approximately 90 m)V_(S30) map and associated open-access dataset for the 140 km×200 km region affected by the January 2025 M6.8 Dingri Xizang,China earthquake.This map provides a significantly finer resolution compared to existing V_(S30) maps,which typically use a 30 arcsec grid.The V_(S30) values were estimated using the Cokriging-based V_(S30) proxy model(SCK model),which integrates V_(S30) measurements as primary constraints and utilizes topographic slope as a secondary parameter.The findings indicate that the V_(S30) values range from 200 to 250 m/s in the sedimentary deposit areas near the earthquake’s epicenter and from 400 to 600 m/s in the surrounding mountainous regions.This study showcases the capability of the SCK model to efficiently generate V_(S30) estimations across various spatial resolutions and demonstrates its effectiveness in producing reliable estimations in data-sparse regions.
基金jointly supported by the Director of the Foundation of the Institute of Seismology,China Earthquake Administration(IS201102643)the National Natural Science Foundation of China(41004020)
文摘The spatial and temporal slip distribution of the Lushan earthquake was estimated using teleseismic body wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized Akaike＇ s Bayesian Information Criterion （ABIC）. The inversion generated the source parameters. Strike, dip and slip were 218°, 39° and 100. 8° ,respectively. A seismic moment （M0） was 2. 1 × 10^20 Nm with a moment magnitude （Mw） of 6. 8, and a source duration was approximately 30 second. The rupture propagated along the dip direction, and the maximum slip occurred at the hypocenter. The maximum slip was approximately 2. 1 m, although this earthquake did not cause an apparent surface rupture. The energy was mainly released within 10 second. In addition, the Lushan earthquake was apparently related to the 2008 Wenchuan earthquake. However, the question of whether it was an aftershock of the Wenchuan earthquake requires further study.
基金supported by the Special Fund of the Institute of Geophysics,China Earthquake Administration(Nos.DQJB2B28 and DQJB22X09)the National Natural Science Foundation of China(No.52192675).
文摘Stochastic finite-fault simulations are effective for simulating ground motions and are widely used in engineering to determine the impacts of ground motion and develop relevant predictive equations.In this study,the source,path,and site amplification coefficient of western Sichuan Province,China,and stochastic finite-fault simulations were used to simulate the acceleration time series,Fourier amplitude spectra,and 5%damped response spectra of 28 strong-motion stations with rupture distances within 300 km of the 2022 MS6.8 Luding earthquake.The simulation results of 14 stations at rupture distances of 45-185 km match the observation.However,the simulation results of 3 near-and 6 far-field stations at rupture distances of 12-36 km and 222-286 km,respectively,were obviously deviated from the observations.Simulation results of the near-field stations are larger than the observations at high frequencies(>6 Hz).The discrepancy likely comes from the nonlinear site effect of near-field stations,which reduced the site amplification at high frequencies.Simulation result of the far-field stations is smaller than the observation at frequencies above 1 Hz.As these stations are located close to the Longmenshan Fault Zone(LFZ),thus,we obtained a new quality factor(Q)from data of historical events and stations located around LFZ.Using the new Q value,the discrepancies of the high-frequency simulation results of the far-field stations were corrected.This result indicated that the laterally varying Q values can be used to address the impact of strong crustal lateral heterogeneity on simulation.
基金supported by the National Natural Science Foundation of China(No.42120104002)the Program of China-Pakistan Joint Research Center on Earth Sciences.
文摘A M_(S)6.8 earthquake occurred on 5th September 2022 in Luding county,Sichuan,China,at 12:52 Beijing Time(4:52 UTC).We complied a dataset of PGA,PGV,and site vS30 of 73 accelerometers and 791 Micro-Electro-Mechanical System(MEMS)sensors within 300 km of the epicenter.The inferred v_(S30)of 820 recording sites were validated.The study results show that:(1)The maximum horizontal PGA and PGV reaches 634.1 Gal and 71.1 cm/s respectively.(2)Over 80%of records are from soil sites.(3)The v_(S30)proxy model of Zhou J et al.(2022)is superior than that of Wald and Allen(2007)and performs well in the study area.The dataset was compiled in a flat file that consists the information of strong-motion instruments,the strong-motion records,and the v_(S30)of the recording sites.The dataset is available at https://www.seismisite.net.
文摘Since the 1970s, Chinese seismologists have started to conduct the Annual Consultation on the Likelihood of Coming Earthquakes in the Next Year. This approach has unique scientific and practical merits either as an active response to the social needs in the situation that earthquake prediction research meets many difficulties, or as a real forward prediction test persistently conducted for 1/3 century. It is a pity that such an approach has not been well-known by international seismological community, and the scientific merits of such an endeavor is sometimes regrettably underestimated.
基金Special Fund for Basic Scientific Research, IGPCEA (DQJB06B03)National Program for Key Science and Technology Projects during the 11th Five-year Plan Period (2006BAC01B03-04-04)Contribution No.08FE3004, Institute of Geophysics, China Earthquake Administration.
文摘On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002~2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of restrictions on the computation environment and condition, e.g., the earthquakes are densely concentrated, selected stations are limited in range, the number of stations in- volved in the computation is larger than 5 and linear fitting features high precision and small error. Under these restrictions, the study shows that vP/vS in and around Wen’an and Tangshan underwent a normal-low-normal proc- ess one year before Wen’an earthquake, vP/vS became obviously low and the low ratio lasted for about one year, meanwhile, little variation of vP/vS was seen in Xingtai, northwest of Beijing, southwest of Beijing, Beijing-Tianjin and Beijing; after the quake, the vP/vS returned normal in Wen’an and Tangshan. Error and stability analysis of the calculated result for vP/vS shows it is convincible that anomaly appeared in and around Wen’an and Tangshan be- fore Wen’an earthquake.
基金supported by the China National Key R&D Program (No.2018YFC1503305)the Special fund of the Institute of Geophysics,China Earthquake Administration (No.DQJB22Z04)。
文摘Investigating spatiotemporal changes in crustal stress associated with major earthquakes has implications for understanding seismogenic processes.However,in individual earthquake cases,the characteristics of the stress after it reaches its maximum value are rarely discussed.In this study,we use the 2021 M_S6.4 Yangbi earthquake in Yunnan,China and events of magnitudes M_L≥3.0 occurred in the surrounding area in the previous 11 years to investigate the spatiotemporal evolution of apparent stress.The results indicate that apparent stress began to increase in January 2015 and reached a maximum in January 2020.Apparent stress then remained at a high level until October 2020,after which it declined considerable.We suggest that the stress was in the accumulation stage from January 2015 to January 2020,and entered the meta-instability stage after October 2020.During the meta-instability stage,the zone of decreasing stress expanded continuously and the apparent stress increased around the Yangbi earthquake source region.These features are generally consistent with the results of laboratory rock stress experiments.We propose that apparent stress can be a good indicator for determining whether the stress at a specific location has entered the meta-instability stage and may become the epicenter of an impending strong earthquake.
基金supported from the National Natural Science Foundation of China(No.42374081)the Fundamental Research Funds for the Institute of Geophysics,China Earthquake Administration(Nos.DQJB23B22,DQJB22K36 and DQJB23Z04)Hong Research Grants Council(Nos.14306122 and 14308523)。
文摘The 6 August 2023 M_(W)5.5 Pingyuan earthquake is the largest earthquake in the central North China Plain(NCP)over the past two decades.Due to the thick sedimentary cover,no corresponding active faults have been reported yet in the epicenter area.Thus,this earthquake presents a unique opportunity to delve into the buried active faults beneath the NCP.By integrating strong ground motion records,high-precision aftershock sequence relocation,and focal mechanism solutions,we gain insights into the seismotectonics of the Pingyuan earthquake.The aftershocks are clustered at depths ranging from 15 to 20 km and delineate a NE-SW trend,consistent with the distribution of ground motion records.A NE-SW nodal plane(226°)of the focal mechanism solutions is also derived from regional waveform inversion,suggesting that the mainshock was dominated by strike-slip motion with minor normal faulting component.Integrating regional geological data,we propose that an unrecognized fault between the NE-SW trending Gaotang and Lingxian-Yangxin faults is the seismogenic fault of this event.Based on the S-wave velocity structure beneath the NCP,this fault probably extends into the lower crust with a high angle.Considering the tectonic regime and stress state,we speculate that the interplay of shear strain between the Amurian and South China blocks and the hot upwelling magma from the subducted paleo Pacific flat slab significantly contributed to the generation of the Pingyuan earthquake.
基金supported by the National Natural Science Foundation of China(No.42120104002)Science for Earthquake Resilience(No.XH23052C)the Program of China-Pakistan Joint Research Center on Earth Sciences.
文摘1.Introduction On December 18,2023,a M6.2 earthquake struck central China with epicenter at Jishishan,Gansu(35.70°N,102.79°E).In the USGS Latest Earthquake platform,the event was identified as M_(W)5.9,35.743°N,102.827°E,labeled 37 km WNW of Linxia Chengguanzhen,China.This study presents an open-access dataset comprising PGA and PGV records of the main-shock from 202accelerometers and 539 Micro-Electro-Mechanical System(MEMS)sensors within two arcdegrees of the epicenter.
基金the Special Fund of China Seismic Experimental Site(Nos.2019CSES0103,2018CESE0102 and 2016CESE0203)the National Natural Science Foundation of China(Nos.41630210,41674060,41974054,and 41974061)the“Active Faults Exploration and Seismic Hazard Assessment in Weihai City”funded by Weihai Municipal People's Government.
文摘For city planning and reducing potential earthquake risk,it’s necessary to detect the information of the buried faults in an urban area especially,including the location and activities.An integrated technique with geophysical and geological methods,including the shallow seismic reflection profile,electrical resistivity measurement,geologic borehole section,and exploration trench,was used to detect the Chengnanhe fault,which is one of the two main faults passing through the Weihai urban area in Shandong province,China.The results show that it is a normal fault striking with E-W direction,and it is relatively inactive and stable.By using the thermoluminescence(TL)dating,we found that the Chengnanhe fault initiated in mid-Pleistocene and there was no offset after late Pleistocene.Such an integrated technique with multiple geological and geophysical methods provides a significant assessment of earthquake risk for city planning in urban areas.
基金Funded by the National Key Research and Development Program(2022YFC3003502).
文摘Paleoearthquake research represents an essential method for determining recurrence intervals oflarge earthquakes.Reasonable determination of the average recurrence interval and coefficient of variationprovides a crucial basis for the analysis of the recurrence characteristics of strong earthquakes on intraplatefaults in Chinese mainland.Paleoearthquake data from 145 fault segments of 93 well-studied faults in MainlandChina were collected,organized,and analyzed to discuss the rational estimation of the average recurrenceinterval and coefficient of variation of a strong earthquake occurrence probability model.First,differencesin structural environments were used as a basis to investigate the spatial distribution characteristics of theaverage recurrence intervals of strong earthquakes.The results indicate significant variations in the recurrenceperiods of strong earthquakes in the Sichuan–Yunnan,Xinjiang,North China,and northeastern Qinghai-Tibet Plateau structure zones.The Sichuan–Yunnan structure zone exhibited the shortest average recurrence intervalfor strong earthquakes,which was mainly distributed between 100 and 2000 years,and a relatively high sliprate.The Xinjiang structure zone attained a relatively balanced recurrence interval frequency distribution of1000–4500 years and a moderate slip rate.The North China structure zone showed the lowest slip rate,withthe strong earthquake recurrence interval mainly concentrated between 1000 and 4000 years.The northeastern Qinghai-Tibet Plateau structure zone presented two main frequency peaks in the strong earthquake recurrenceintervals between 1000–3000 years and 3000–5000 years and a relatively high slip rate.The slip rate is a keyfactor influencing the recurrence interval of strong earthquakes,and active faults with high slip rates showshort recurrence intervals.Furthermore,the relationship between fault slip rate,fault type,and the averagerecurrence interval of strong earthquakes was examined.The results indicate a good logarithmic linearrelationship between the fault slip rate and the average recurrence interval of large earthquakes—the higherthe slip rate,the shorter the recurrence interval of strong earthquakes.Fault type also showed a relation to theaverage recurrence interval,with the intervals for various types of active faults gradually increasing in theorder of strike-slip,normal,reverse strike-slip,reverse,and normal strike-slip faults.Second,we calculated theproportions of active faults and various fault types in each structure zone that had a coefficient of variation inrecurrence intervals less than 0.4.The findings reveal that the occurrence of strong earthquakes on most activefaults in Chinese mainland satisfies a quasiperiodic model.The general coefficient of variation across differentstructure zones and fault types ranges between 0.36 and 0.44,which indicates the nonsignificant difference inthe degree of variability in the periodicity of strong earthquake occurrence across various structural zones andfault types.
基金supported by the Special Fund of the Institute of Geophysics,China Earthquake Administration(grant no.DQJB24X25).
文摘The Low Earth Orbit(LEO)geomagnetic satellites provide a large number of high-precision measurements,which are crucial for researching the Secular Variation(SV)of the geomagnetic field.We employ the combined constellation data from the Chinese Seismo-Electromagnet Satellite(CSES)and Swarm satellites to extract the SV in China and surrounding areas,based on the Geomagnetic Virtual Observatory(GVO)method.On this basis,we have developed two GVO products:the core field,and the SV series.The accuracies of these products are assessed using ground observatories measurements and geomagnetic field model.Moreover,the results indicate that the GVO products align well with the series from ground observatories and the CHAOS model.The majority of root-mean-square deviation(RMSE)values of the core field series are less than 5 nT,consistent with the INTERMAGNET standards for quasi-definitive data.In the GVO core field series,the maximum accuracy of one-month and four-month intervals are 2.24 nT and 1.16 nT,respectively.In the GVO SV series,the maximum accuracy of one-month and four-month intervals are 2.03 nT/yr and 1.36 nT/yr,respectively.The GVO SV series effectively capture geomagnetic jerks without losing temporal resolution comparing with the recording of ground observatories.We demonstrate that the GVO method serves as an effective and precise tool for extracting SV information of geomagnetic fields.In the GVO products,the RMSE of the horizontal component exceeds that of the vertical component,and the magnitude of RMSE deviation correlates with solar activity levels.With more and more geomagnetic satellites in orbit,we wish to use multi-constellation magnetic satellite data to assess the geomagnetic field more accurately.
基金funded by the National Key Research and Development Program of China(2022YFC3003502)。
文摘Local strong seismic activity shows the potential to closely follow a renewal process,which is inconsistent with the overall seismic activity that aligns with the Poisson process.Given that existing methods for synthesizing stochastic seismic event sets cannot control local seismic activity,a method based on Monte Carlo simulations has been developed for synthesizing random seismic event sets where local strong earthquakes satisfy the renewal process.This method can synthesize seismic activities in a statistical area where the overall activity conforms to the Poisson process and the major seismic activities in local potential sources or faults follow the renewal process.This paper presents long-and short-scale approaches.The long-scale earthquake catalogs are suitable for reflecting the sequential characteristics of seismic activities.Meanwhile,the short-scale catalogs focus on the impacts of specific earthquake events within a group for a detailed understanding of hazards under certain conditions,making them suitable for studies on specific earthquake sequences and geological areas or situations requiring high temporal resolution.In the applications of shortscale sequences,we find that the equivalent occurrence rate method may overestimate the seismic hazard.This synthesis method for earthquake catalogs can simulate realistic seismic activities,thereby enhancing the accuracy of hazard analysis results and is suitable for seismic hazard analysis and earthquake insurance rate setting.
基金supported by the National Natural Science Foundation of China(No.42474081)the Fundamental Research Funds from the Institute of Geophysics,China Earthquake Administration(No.DQJB 23K34)the Science and Technology Department of Henan Province of China(No.242102320039).
文摘The spatial autocorrelation(SPAC)(also known as the Aki’s spectral method)of ambient seismic noise has been widely adopted in surface wave phase velocity extraction.In two-dimensional cases,the surface wave velocity can be calculated by fitting the SPAC coefficients with the zero-order Bessel function of the first kind or using the zeros of the Aki’s spectrum.This method has also been extended to active-source records.This study examined the application of the zeros of Aki’s spectra on active-source records using theoretical analysis and numerical simulation.We show that the zeros of the Aki’s spectrum should be associated with the zeros of the cosine function instead of the zeros of the zero-order Bessel function when extracting the phase velocity of the surface wave,considering the data acquisition and processing of the active-source records.The proposed method was then applied to the active-source data from methane explosion experiments collected using a dense array in Tongzhou,the subcenter of Beijing,for extracting the phase velocity of Rayleigh wave.The extracted dispersion curves were integrated with those obtained by beamforming the ambient noise to yield broadband dispersion curves at 0.3–6 Hz.This provides insightful results at high frequencies,at which less information can be obtained through the passive-source beamforming.The combing phase velocities from active-source with those obtained from ambient noise provide a better constrain on the shallow structure.Based on the combined fundamental mode dispersion curves at 28 excitation points,the S-wave velocity structure below the dense array is obtained by depth inversion.Due to the constraints imposed by the high-frequency information from active source,the estimated vS30 are more reliable and can be used to the site classification.
基金the support of National Natural Science Foundation of China(Grant Numbers 52192675 and 52378541)。
文摘Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure.This study employs historical data from the M 7.5 earthquake that occurred in 1850 to simulate the impacts of a M 7.5 event on hydropower stations located in proximity to Xichang.Key factors taken into account in the simulation of seismic motion encompass uncertainties,mixed-source models,and the placement of asperities.Through these simulations,we acquired the peak ground acceleration(PGA),acceleration time histories,and acceleration response spectra for the hydropower facilities affected by the earthquake.To perform a comprehensive analysis,we utilized a multi-scenario stochastic finite fault simulation method to estimate parameters including the minimum,average,and maximum values of PGA and pseudo-spectral acceleration(PSA)response spectra.Additionally,we assessed the 50^(th),84^(th),and 95^(th)percentiles values of the peak ground acceleration and pseudo-spectral acceleration response spectra.The simulation results also include peak ground acceleration field maps and peak ground velocity(PGV)field maps and intensity distribution maps pertaining to the earthquake.The findings demonstrate that the intensity maps produced through the stochastic finite fault method closely correspond with the intensity contour maps published of historical seismic records.These findings offer significant insights for the seismic safety evaluation and design of the specified hydropower stations.Moreover,this multi-scenario methodology can be effectively utilized for other critical infrastructure projects to derive dependable seismic motion parameters.
