摘要
2022年9月17—18日,中国台湾先后发生台东县M_(S)6.5和花莲县M_(S)6.9两次强震及多次余震。两次强震均为逆走滑型地震,且震中都位于台湾纵谷断裂带,该地区构造复杂,为晚中生代古太平洋板块朝东亚陆缘的消减带,具有逆冲型构造应力背景。对纵谷断裂带周围地区历史上发生过的地震进行统计发现,大部分地震为逆断型。为探究该地区此次发生逆走滑型地震的原因及其与构造应力场的关系,首先通过搜集研究区相关的地震震源机制,反演该地区的构造应力场,明确其是以走向为北西西向的压应力为主的应力场;然后将应力场投影到走向、倾角不同的断层面上,发现一些节面上表现出较大的相对剪应力和较小的相对正应力,说明这些节面上具有较强的剪切作用和较小的摩擦力,容易发生错动而产生逆断型、逆走滑型和走滑型的地震。同时,为明确短时间内两次强震间的触发关系,通过计算M_(S)6.5地震在M_(S)6.9地震破裂面和滑动方向上产生的库伦破裂应力变化发现,M_(S)6.9地震约在0.02MPa的库伦破裂应力触发下发生。相关结论对研究台湾纵谷带地震的发震机理和地球动力学具有一定的指导意义。
On September 17th and 18th,2022,two earthquakes struck Taiwan Province of China in Taitung County and Hualien County,respectively,measuring M_(S)6.5 and M_(S)6.9 in magnitude,followed by multiple aftershocks.Both seismic events were situated along the Longitudinal Valley Fault and exhibited a reverse strike-slip mechanism.The geological setting in this area is intricate,as the Longitudinal Valley Fault zone represents a subduction zone where the late Mesozoic Paleo-Pacific plate converges with the East Asian continental margin,resulting in a predominant thrust-type tectonic stress background.However,historical earthquake data in this region have indicated a prevalence of reverse-faulting earthquakes.To address the causes of these reverse strike-slip fault earthquakes and their relationship with the tectonic stress field in the area,we first reconstructed the tectonic stress field by analyzing the focal mechanisms of past earthquakes within the study area.The resulting stress field was characterized by compressive stress oriented with an azimuth of NWW.Subsequently,this stress field was projected onto fault planes with various strike and dip angles.This analysis revealed that certain fault joints experienced more significant relative shear stress and lower relative normal stress,suggesting that these joints were more prone to dislocation,leading to earthquakes of the reverse fault type,reverse strike-slip type,and strike-slip type.Furthermore,the proximity and timing of the two earthquakes within a two-day span prompted an examination of their potential triggering relationship.Researchers calculated the Coulomb rupture stress changes caused by theM_(S)6.5 earthquake on the rupture plane of the M_(S)6.9 earthquake and its sliding direction.Their analysis indicated an increase of approximately 0.02 MPa in Coulomb rupture stress,suggesting that the Taitung M_(S)6.5 earthquake may have triggered the Hualien M_(S)6.9 earthquake.This study holds significant importance for understanding the seismogenic mechanism of the L
作者
黄少华
万永革
冯淦
李枭
关兆萱
HUANG Shaohua;WAN Yongge;FENG Gan;LI Xiao;GUAN Zhaoxuan(School of Geosciences,Institute of Disaster Prevention,Sanhe 065201,Hebei,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,Hebei,China)
出处
《地质力学学报》
CSCD
北大核心
2023年第5期674-684,共11页
Journal of Geomechanics
基金
国家自然科学基金项目(42174074,41674055)
中央高校科研业务费专项(ZY20215117)
河北省地震动力学重点实验室开放基金项目(FZ212105)。
关键词
纵谷断裂带
应力场
应力体系
库伦破裂应力
Longitudinal Valley Fault
stress field
stress system
Coulomb failure stress
