龙门山断裂带南段岩石圈磁场变化分析  

Variation of the Lithospheric Magnetic Field in the Southern Segment of the Longmenshan Fault Zone

作　　者：宋成科[1] 倪喆[2] 陈斌[3] 袁洁浩[3] SONG Chengke;NI Zhe;CHEN Bin;YUAN Jiehao(First Crust Monitoring and Application Center,CEA,Tianjin 300180,China;Earthquake Agency of Yunnan Province,Kunming 650224,Yunnan,China;Institute of Geophysics,China Earthquake Agency,Beijing 100081,China)

机构地区：[1]中国地震局第一监测中心,天津300180 [2]云南省地震局,云南昆明650224 [3]中国地震局地球物理研究所,北京100081

出　　处：《地震工程学报》2019年第6期1529-1535,共7页China Earthquake Engineering Journal

基　　金：国家自然科学基金(41804091);中国地震局地震科技星火计划项目(XH18067Y)

摘　　要：根据巴颜喀拉块体东部2011—2014年3期岩石圈磁场年变化情况,结合地壳应力资料,重点分析龙门山断裂带南段的岩石圈磁场变化与应力积累的关系。该区域2011—2012年和2012—2013年岩石圈磁场变化明显弱于周边区域,实测地壳应力结果反映汶川M S8.0地震震后应力积累水平很高。压磁效应分析认为汶川M S8.0地震后该区域高应力积累、低应变率的动力学背景是控制该区域岩石圈磁场弱变化的主要因素。此外,芦山M S7.0地震及康定M S6.3地震前震中区存在局部岩石圈磁场水平矢量的弱变化现象,尤其是2012—2013年水平矢量大小和方向均与周边区域相比存在明显差异,这可能是两次地震的前兆异常。According to known annual variations in the lithospheric magnetic field along the eastern segment of the Bayan Har block during the 2011-2014 period and crust stress data,the relationship between the lithospheric magnetic field and stress accumulation in the southern segment of the Longmenshan fault zone was studied.Annual variations in the lithospheric field in the local area was weaker than for surrounding areas during 2011-2012 and 2012-2013.High-stress accumulation was reflected in in-situ crust stress measurement after the Wenchuan MS8.0 earthquake.Based on analysis of the piezomagnetic effect,it was concluded that the tectonic background of high-stress accumulation and low strain rate in the local area after Wenchuan MS8.0 earthquake was the main factor controlling the weak variations in the lithospheric magnetic field.Additionally,the horizontal component of the lithospheric field in the area of the epicenter became weak before the Lushan MS7.0 and Kangding M S6.3 earthquakes.Both magnitude and direction of the horizontal vector for the 2012-2013 period differed across the surrounding area,which may be a precursor of two earthquakes.

关 键 词：巴颜喀拉块体东部 岩石圈磁场 地壳应力 地震活动 

分 类 号：P318[天文地球—固体地球物理学]