2016年门源M_S6.4地震孕育—发生的地形变异常特征  

Anomalies on Characteristics of Crustal Deformation During the Pregnant Process of the Menyuan M_S6.4 Earthquake

作　　者：张希[1] 秦姗兰[1] 贾鹏[1] 李瑞莎[1] ZHANG Xi;QIN Shan-lan;JIA Peng;LI Rui-sha(The Second Monitoring Center,Xi'an 710054,China)

机构地区：[1]中国地震局第二监测中心

出　　处：《地震》2019年第4期27-38,共12页Earthquake

基　　金：中国地震局地震预测研究所统筹科研项目

摘　　要：利用1999-2007年、 2009-2015年和2015-2017年即2016年1月21日门源MS6.4地震前后的GPS水平运动资料,以及震区周边200 km半径范围内跨断层流动短水准观测数据,借助GPS视应变场计算、冷龙岭断裂剖面的负位错反演,以及跨断层形变强度新指标的提炼,综合分析此次强震前相关断裂的中-长期闭锁背景以及断裂活动的中-短期动态演变过程。结果显示:①2009-2015年相对1999-2007年,祁连山构造区中东部GPS站点间差异运动和挤压变化增强;跨断层短水准观测也显示震前2年左右时间内相似的断裂活动或形变应变加速特征。②分层非均匀负位错反演揭示与地震相关的冷龙岭等断裂1999-2007年即震前十数年长期闭锁, 2009-2015年即震前6年半上-中层即地表以下0~15.6 km深度闭锁程度明显增大。③震区周边半径200 km内跨断层形变强度新指标显示出震前半年内逆断稍占优势的变幅加剧异常,反映中短期前兆。Using the GPS horizontal movement data during 1999-2007, 2009-2015 and 2015-2017 before and after the Menyuan MS6.4 earthquake in January 21, 2016, as well as the mobile short-leveling observational data of cross-fault within the radius of 200 km around the epicenter, aid by the calculation of GPS apparent strain field, negative dislocation inversion of Lenglongling fault profile and the extraction of new index of cross-fault deformation intensity, the medium-long term locking background of related fault and medium-short term dynamic evolution process of fault activities were comprehensively analyzed. The results show that: ① the differential movement and compression variation between GPS stations in the middle-eastern Qilian Mountains tectonic area increased during 2009-2015 compared with 1999-2007;the short-leveling observation of cross-faults also showed similar acceleration characteristics of fault activity or deformation-strain in about 2 years before this earthquake. ② Layered non-uniform negative dislocation inversion revealed that the Lenglongling faults related to this earthquake were locked for a long time in 1999-2007, more than ten years before this earthquake;and locking degree increased in the depth of 0~15.6 km below the surface during 2009-2015, six and a half years before this earthquake. ③ The new index of cross-fault deformation intensity in the range of 200 km radius around the epicenter showed that accelerating of variation amplitude which slightly displayed thrust feature in half a year before the earthquake, reflecting medium-short-term precursors.

关 键 词：负位错反演 GPS 跨断层水准 2016年门源MS6.4地震 

分 类 号：P315.7[天文地球—地震学]