Earthquakes can cause widely distributed slope failures and damage in mountainous areas.The accurate prediction of ground motions in mountainous areas is essential for managing the seismic risk of urban cities near mo...Earthquakes can cause widely distributed slope failures and damage in mountainous areas.The accurate prediction of ground motions in mountainous areas is essential for managing the seismic risk of urban cities near mountains but is restricted primarily by complex seismic site amplification effects in areas of uneven terrain.This study selected Qiaozhuang town located in the Qingchuan–Pingwu fault zone,Southwest China,as a case study.A simulator for mapped seismic responses using a hybrid model(Si Se RHMap)was applied to compute the multispectral seismic topographic amplification maps at the three slope units surrounding Qiaozhuang town(Weigan hill,Mt.Dong,and Mt.Shizi).Post-earthquake damage survey maps,1 D seismic site response spectral ratios,and H/V spectral ratios of earthquake data were used to validate the computed seismic site amplification factors and resonance frequencies.The results suggest that strong topographic amplification effects usually occur at distinct slope locations,such as hilltops,convex slope positions,upslope,and narrow ridges.The computed topographic amplification factors in the study area reached up to 2.4 at upslope or hilltops,and the resonance frequencies were between 3 and 10 Hz.Topographic effects can be as important as stratigraphic effects when assessing seismic amplification effects in the study area.We conclude that both topographic and stratigraphic effects should be considered in the comprehensive seismic hazard assessment of the study area or other similar mountain towns.展开更多
Earthquake data include informative seismic phases that require identification for imaging the Earth's structural interior.In order to identify the phases,we created a numerical method to calculate the traveltimes...Earthquake data include informative seismic phases that require identification for imaging the Earth's structural interior.In order to identify the phases,we created a numerical method to calculate the traveltimes and raypaths by a shooting technique based upon the IASP91 Earth model,and it can calculate the traveltimes and raypaths for not only the seismic phases in the traditional traveltime tables such as IASP91,AK135,but also some phases such as pPcP,pPKIKP,and PPPPP.It is not necessary for this method to mesh the Earth model,and the results from the numerical modeling and its application show that the absolute differences between the calculated and theoretical traveltimes from the ISAP91 tables are less than 0.1 s.Thus,it is simple in manipulation and fast in computation,and can provide a reliable theoretical prediction for the identification of a seismic phase within the acquired earthquake data.展开更多
Strong aftershocks generally occur following a significant earthquake.Aftershocks further damage buildings weakened by mainshocks.Thus,the accurate and efficient prediction of aftershock-induced damage to buildings on...Strong aftershocks generally occur following a significant earthquake.Aftershocks further damage buildings weakened by mainshocks.Thus,the accurate and efficient prediction of aftershock-induced damage to buildings on a regional scale is crucial for decision making for post-earthquake rescue and emergency response.A framework to predict regional seismic damage of buildings under a mainshock-aftershock(MS-AS)sequence is proposed in this study based on city-scale nonlinear time-history analysis(THA).Specifically,an MS-AS sequence-generation method is proposed to generate a potential MS-AS sequence that can account for the amplification,spectrum,duration,magnitude,and site condition of a target area.Moreover,city-scale nonlinear THA is adopted to predict building seismic damage subjected to MS-AS sequences.The accuracy and reliability of city-scale nonlinear THA for an MS-AS sequence are validated by as-recorded seismic responses of buildings and simulation results in published literature.The town of Longtoushan,which was damaged during the Ludian earthquake,is used as a case study to illustrate the detailed procedure and advantages of the proposed framework.The primary conclusions are as follows.(1)Regional seismic damage of buildings under an MS-AS sequence can be predicted reasonably and accurately by city-scale nonlinear THA.(2)An MS-AS sequence can be generated reasonably by the proposed MS-AS sequencegeneration method.(3)Regional seismic damage of buildings under different MS-AS scenarios can be provided efficiently by the proposed framework,which in turn can provide a useful reference for earthquake emergency response and scientific decision making for earthquake disaster relief.展开更多
基金financially supported by the Funds for Creative Research Groups of China(Grant No.41521002)the National Natural Science Foundation of China(Grant No.42077257)the Open Fund of the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Grants No.SKLGP2019K024 and No.SKLGP2019K006 assigned for G.Grelle’s competition proposal)。
文摘Earthquakes can cause widely distributed slope failures and damage in mountainous areas.The accurate prediction of ground motions in mountainous areas is essential for managing the seismic risk of urban cities near mountains but is restricted primarily by complex seismic site amplification effects in areas of uneven terrain.This study selected Qiaozhuang town located in the Qingchuan–Pingwu fault zone,Southwest China,as a case study.A simulator for mapped seismic responses using a hybrid model(Si Se RHMap)was applied to compute the multispectral seismic topographic amplification maps at the three slope units surrounding Qiaozhuang town(Weigan hill,Mt.Dong,and Mt.Shizi).Post-earthquake damage survey maps,1 D seismic site response spectral ratios,and H/V spectral ratios of earthquake data were used to validate the computed seismic site amplification factors and resonance frequencies.The results suggest that strong topographic amplification effects usually occur at distinct slope locations,such as hilltops,convex slope positions,upslope,and narrow ridges.The computed topographic amplification factors in the study area reached up to 2.4 at upslope or hilltops,and the resonance frequencies were between 3 and 10 Hz.Topographic effects can be as important as stratigraphic effects when assessing seismic amplification effects in the study area.We conclude that both topographic and stratigraphic effects should be considered in the comprehensive seismic hazard assessment of the study area or other similar mountain towns.
文摘Earthquake data include informative seismic phases that require identification for imaging the Earth's structural interior.In order to identify the phases,we created a numerical method to calculate the traveltimes and raypaths by a shooting technique based upon the IASP91 Earth model,and it can calculate the traveltimes and raypaths for not only the seismic phases in the traditional traveltime tables such as IASP91,AK135,but also some phases such as pPcP,pPKIKP,and PPPPP.It is not necessary for this method to mesh the Earth model,and the results from the numerical modeling and its application show that the absolute differences between the calculated and theoretical traveltimes from the ISAP91 tables are less than 0.1 s.Thus,it is simple in manipulation and fast in computation,and can provide a reliable theoretical prediction for the identification of a seismic phase within the acquired earthquake data.
基金The authors are grateful for the financial support received from the National Key R&D Program(Grant No.2018YFC1504401)the National Natural Science Foundation of China(Grant No.51778341).
文摘Strong aftershocks generally occur following a significant earthquake.Aftershocks further damage buildings weakened by mainshocks.Thus,the accurate and efficient prediction of aftershock-induced damage to buildings on a regional scale is crucial for decision making for post-earthquake rescue and emergency response.A framework to predict regional seismic damage of buildings under a mainshock-aftershock(MS-AS)sequence is proposed in this study based on city-scale nonlinear time-history analysis(THA).Specifically,an MS-AS sequence-generation method is proposed to generate a potential MS-AS sequence that can account for the amplification,spectrum,duration,magnitude,and site condition of a target area.Moreover,city-scale nonlinear THA is adopted to predict building seismic damage subjected to MS-AS sequences.The accuracy and reliability of city-scale nonlinear THA for an MS-AS sequence are validated by as-recorded seismic responses of buildings and simulation results in published literature.The town of Longtoushan,which was damaged during the Ludian earthquake,is used as a case study to illustrate the detailed procedure and advantages of the proposed framework.The primary conclusions are as follows.(1)Regional seismic damage of buildings under an MS-AS sequence can be predicted reasonably and accurately by city-scale nonlinear THA.(2)An MS-AS sequence can be generated reasonably by the proposed MS-AS sequencegeneration method.(3)Regional seismic damage of buildings under different MS-AS scenarios can be provided efficiently by the proposed framework,which in turn can provide a useful reference for earthquake emergency response and scientific decision making for earthquake disaster relief.
