摘要
2021年5月22日2时4分位于青藏高原巴颜喀拉地块内部青海果洛州玛多县发生了M_(S)7.4地震(玛多M_(S)7.4地震),震中位于98.34°E,34.59°N,震源深度17 km(中国地震台网中心测定).震后区域应力调整直接导致了周边断层的库仑应力变化和主震断层外余震的发生,进而影响到区域地震活动性并改变了即发地震概率.本文利用有限断层滑移模型计算了青海玛多地区主要断层的库仑应力变化,结合Dieterich地震发生率模型,给出了库仑应力扰动下超越某一特定震级地震的发震概率公式,得到了受青海玛多M_(S)7.4地震所产生的库仑应力场的影响周边8条断裂(段)分别发生M_(S)≥7.0和M_(S)≥6.0地震的概率变化.结果表明,8条断裂(段)的发震概率均有不同程度的增加.对于发震概率增幅较为明显的甘德南缘断裂、玛多—甘德断裂和西藏大沟—昌马河断裂在震后短时间内(约10年内)发震概率迅速提升,之后趋于平稳,不排除有潜在发生破坏性地震的可能,特别是发生M_(S)≥6.0地震的可能性.针对达日断裂,由于库仑应力增加造成的影响不明显,短期内发生M_(S)≥7.0或M_(S)≥6.0地震的可能性不大,但随着时间的推移,不排除几十年后有潜在发生破坏性地震的可能,尤其要关注发生M_(S)≥6.0地震的可能性;东昆仑断裂特别是玛沁—玛曲段仍然是未来强震发生的可能区段,需重点关注和防范M_(S)≥6.0地震乃至M_(S)≥7.0地震的发生;玉树—甘孜断裂发生M_(S)≥6.0地震,尤其是发生M_(S)≥7.0地震的危险性不高,而乌兰乌拉湖—玉树南断裂有潜在发生破坏性地震的风险,对于M_(S)≥6.0以上地震需要加强防范.
On May 22,2021,a M_(S)7.4 earthquake occurred in Madoi County,Guoluo Prefecture,Qinghai Province.The epicenter was located at 98.34°E and 34.59°N(Officially determined by China Earthquake Networks Center).The earthquake occurred inside the Bayan Har block with a focal depth of 17 km.The regional stress adjustment after a major earthquake directly causes the surrounding faults to undergo Coulomb stress changes,which affects the rate of seismic activity,off-fault aftershocks,and probability changes of occurrence of impending earthquakes.This paper uses the fault slip model to calculate Coulomb stress changes of main faults in Madoi area of Qinghai.Using the Dieterich earthquake occurrence rate model,a formula for the occurrence probability of an earthquake exceeding a certain magnitude under the Coulomb stress disturbance is obtained.We calculate the probability changes of M_(S)≥7.0 and M_(S)≥6.0 earthquake occurrence of the surrounding 8 faults(segments)which caused by the Coulomb stress increase.Affected by the Qinghai Madoi M_(S)7.4 earthquake,the probability of the 8 faults earthquake occurrence has increased to varying degrees.For the Gadain South Margin fault,Madoi-Gadain fault and Tibet Dagou-Changmahe fault,the probability of earthquakes occurrence has increased rapidly in a short period of time(within about 10 years)after the main shock and it has stabilized later.There is a potential for destructive earthquakes,especially for earthquakes with M_(S)≥6.0.For the Dari fault,since the increase in Coulomb stress has little effect,it is unlikely to occur M_(S)≥7.0 or M_(S)≥6.0 in the short term.However,as time goes by,the possibility of potentially destructive earthquakes occurring decades later cannot be ruled out.Particular attention to the possibility of earthquakes with M_(S)≥6.0 should be paid to.The East Kunlun fault,especially the Maqên-Maqu section,is still a possible section for strong earthquakes in the future.This section still needs to focus on and prevent earthquakes with M_(S)≥6.0
作者
刘博研
解孟雨
史保平
LIU BoYan;XIE MengYu;SHI BaoPing(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;China Earthquake Network Center,Beijing 100045,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第2期563-579,共17页
Chinese Journal of Geophysics
基金
应急管理部国家自然灾害防治研究院基本科研业务专项(ZDJ2017-09)
国家自然科学基金项目(U1939206)资助。
