南北地震带现今应变特征及地震危险性分析

Strain Characteristics of North-South Seismic Zone and the Analysis of Earthquake Risk

基于1999~2007期、2009~2013期及2013~2016期GPS速度场数据,利用最小二乘配置方法解算南北地震带附近区域应变率参数,对比应变率变化并分析变化原因。结合研究时段内M W6.0以上地震的震中分布,分析应变率参数与地震分布的相关关系;再结合地震地质,分析研究区内主要断层的地震危险性。结果显示,青藏高原近期存在加速扩展特征,其东北缘存在明显的介质性质横向不均匀特征,M W6.0以上地震与应变率的大小存在相关关系;研究区内的地震危险区分别为祁连山中段危险区、玛沁-玛曲危险区、安宁河-小江断裂系危险区及红河断裂带中南段危险区。

Using GPS velocity field and the least square collocation method,we calculate and analyze the strain rate fields of the year 1999-2007,2009-2013 and 2013-2016 of the area around the north-south seismic zone in China.The changing of strain rate fields and its internal reasons are analyzed.With epicenters of earthquakes that occurred from the year 2008 to 2018,the relationship between strain rates and epicenters is summarized.Finally,with geological and seismological results,we analyze the earthquake risk in the study area.As results show,in recent years,the Tibet plateau has accelerated its extension,resulting in the increasing strain rates around Qilian block and the eastern margin of Sichuan-Yunnan block;the north-eastern margin of Tibet plateau shows lateral inhomogeneous characteristics;earthquakes of M W≥6.0 are collocated with regions of highest strain rates.Earthquake risk areas can be recognized as the eastern part of Qilian mountain,Maqin-Maqu segment of east Kunlun fault,Anninghe-Xiaojiang fault zone and mid-southern segment of Honghe fault zone.