摘要
2023年12月18日23时59分,甘肃临夏州积石山县发生6.2级地震,造成人员伤亡和财产损失。本次地震发生在青藏高原东北缘地区,受青藏高原向NE向扩展挤压作用的影响,区域发育两组较为典型的断裂构造:NWW向大型左旋走滑断裂带是活动块体运动边界,另一组NNW向右旋走滑断裂则发育在块体内部构成次级块体边界。此次积石山6.2级地震就发生在NWW向西秦岭北缘左旋走滑断裂带和NNW向日月山右旋走滑断裂带之间的大型挤压阶区内,初步判定其发震构造为以逆冲作用为主的拉脊山断裂带东南段的积石山东缘断裂。余震展布范围严格限制在黄河以南的积石山东麓大河家第三系盆地内,根据黄河以北拉脊山和以南的积石山山脊线及坡折带存在较大不连续性,且沿黄河南岸发育较明显的断层三角面等构造地貌特征,推测沿黄河发育有一条调节区内挤压变形差异的横向断裂。断裂切断拉脊山北缘断裂带东南段,使积石山东缘断裂成为一个长度不足40 km的独立活动段,判定原震区近期发生更大地震的可能性不大。
On December 18,an M_(s)6.2 earthquake occurred in Jishishan County,Gansu Province,which causing casualties and property losses.The earthquake occurred on the northeastern margin of the Qinghai-Tibet Plateau where developed two groups of typical fault structures due to the extension of the Qinghai-Tibet Plateau to the northeast.The NWW trending large left-lateral strike-slip faults are seemed as the boundaries of the ac-tive blocks,and the other group of NNW-trending right-lateral strike-slip faults develop within the blocks as the secondary block boundaries.The Jiashishan M_(s)6.2 earthquake oc-curred in the large compression stepover between the NWW-trending left-lateral strike-slip fault zone of the north margin West Qinling and the NNW-trending Riyueshan right-lateral strike-slip fault zone,and the seismogenic tectonic is determined to be the southeastern segment of Lajishan fault zone named eastern margin of Jishishan fault.The distribution of aftershocks are strictly limited to the south of Yellow River and within the Dahejia terti-ary basin in the eastern piedmont of Jishishan.The ridgelines and piedmont lines on the eastern section of Lajishan and Jishishan are discontinuous,and there are fault triangle faces along east bank of Yellow River which flows between the two mountains.It is specu-lated that a transverse fault with the function of adjusting the regional differential com-pression deformation is developed in this area.This fault cuts the southeastern segment of Lajishan fault zone and may make the eastern margin of Jishishan fault to be an independ-ent active segment with a length of less than 40 km.It is determined that the possibility of a larger earthquake occurring in this area is not high in near future.
作者
杨攀新
熊仁伟
胡朝忠
高原
YANG Pan-xin;XIONG Ren-wei;HU Chao-zhong;GAO Yuan(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)
出处
《地震》
CSCD
北大核心
2024年第1期153-159,共7页
Earthquake
基金
国家自然科学基金重点项目(42330311)
中国地震局地震预测研究所基本科研业务费专项(CEAIEF2022030201)。
关键词
2023年积石山6.2级地震
发震构造
青藏高原东北缘
拉脊山断裂带
The 2023 Jishishan M_(s)6.2 earthquake
Seismogenic tectonics
Northeastern margin of the Qinghai-Tibet
Lajishan fault zone