摘要
采用前人反演得到的云南禄劝地震的地震矩张量和主震及部分余震的震源机制解,以该主震震中为中心在全球CMT目录中查询到的部分地震的震源机制解,先将地震矩张量转化为震源机制解,运用精细网格搜索反演方法将震源机制解反演得到禄劝地震和其周边地区的应力场。对反演得出的两个应力场进行差异性对比研究,结果表明禄劝地震震源处主压应力场为NNW—SSE向,主压应力与主张应力相当,周边地区的主压应力方向为NW—SE,断层破裂面倾角大,以走滑正断层为主,主压应力占优势。但是由于云南地区主要由NNW—SSE和NW—SE方向的主压应力控制,并受本文所选的周边地区的经纬度及所处地区的控制,所以该区域在总体上受NW—SE方向的压应力控制,局部地区受NNW—SSE方向的压应力控制。该结果可以用来分析该地区的地震地质背景和断层形成条件,对地球动力环境的研究有一定的意义。
There is a complicated stress state in Yunnan and the main research object in this paper is the Luquan seismic zone. The Luquan seismic belt is located in the Xiaojiang fault zone in the southern section of the North-South Seismic Belt within China＇s borders. The complexity of the stress field of the Luquan seismic zone gives it great research value as the focal-mechanism solu tion in the area contains a great amount of information about the focus of earthquakes. In this pa- per, we use the seismic moment tensor of the Yunnan Luquan earthquake and the focal mecha- nism solution of its main shock and aftershocks from the inversion of previous scholars, and refer to the Global CMT Catalog for the focal mechanism solutions of several earthquakes based on theLuquan earthquake. We transform the seismic moment tensor into a focal mechanism solution and then use a stress-field inversion program to invert the focal mechanism solution and obtain the stress field of the Luquan earthquake and surrounding areas. Then, we compare the differences between the two stress fields. We found the principal compression stress field of the hypocenter in the Yunnan Luquan earthquake to be in the NNW-SSE direction. Also, we found the principal compression stress to be equivalent to the principal extensional stress, and that of surrounding areas to be in the NW-SE direction. Furthermore, the facture surface of faults, mainly down strike-slip faults have a large slope angle and the principal compression stress is in a dominant po- sition. However, we found Yunnan to be primarily affected by the principal compression stress in the NNW-SSE and NW-SE directions, given the impact of its location and the longitude and lati- tude of its surrounding areas. Therefore, in general, Yunnan is affected by compression stress in the NW-SE direction, with some areas affected by compression stress in the NNW-SSE direction. These research results can be used to analyze the mechanism of earthquakes and the seismic geo- logical background and formation conditions of the faults in the area. They also have some signifi- cance in promoting relevant research on the geodynamic environment in the Yunnan region.
作者
周文敏
万永革
张建国
郭威
高冰莹
ZHOU Wen-min WANG Yong-ge ZHANG Jian-guo GUO Wei GAO Bing-ying(Yunnan University, Kunming 650500, Yunnan, China Institute of Disaster Prevention, Langfang 065201, Hebei, China Earthquake Administration of Yunnan Province, Kunming 650224, Yunnan, China Earthquake Administration of Tianjin Municipality, Tianjin 300201, China)
出处
《地震工程学报》
CSCD
北大核心
2017年第2期262-267,277,共7页
China Earthquake Engineering Journal
基金
国家国际合作项目<中国-东南亚毗邻区大震活动地球动力学研究>项目(2015DFA21260)
关键词
禄劝地震
余震
震源机制
应力场
Luquan earthquake
aftershock
focal mechanism
stress field
