Regional Tectonic Deformation Background and Medium- and Short-Term Precursors to the Minl

Regional Tectonic Deformation Background and Medium- and Short-Term Precursors to the Minle-

Shandan Earthquakes

Wang Shuangxu;Cui Duxin;Zhang Xiaoliang;Xue Fuping;Chen Bing

【期刊名称】《中国地震研究（英文版）》 【年(卷),期】2005(019)001

【摘要】Using GPS observations of horizontal movement from 2001 to 2003 and the cross-fault mobile short-levelling data of 1988 ～ 2003, and with the aid of the improved negative dislocation model and the time-varying curve of strain intensity ratio of fault deformation, the regional tectonic deformation background and medium- and short-term precursors related to the preparation of the Minle-Shandan earthquakes of Ms6.1 and Ms5.8 on October 25, 2003 are investigated.The results reveal that, under the background of the wide-range deformation adjustment,short-term relaxation and recovery caused by the Kuulun Mountains earthquake of MsS. 1, the hypocenters of the earthquakes are located on the north edge of the shear stress enhancement zone between the compressional locked segments of block boundary fault, a place which may represent an accelerated strain accumulation. An obvious anomaly of strain intensity ratio appeared in short-levelling measurements crossing over the fault at the Shihuiyaokou site, the closest to the epicenters, 3 months before the occurrence of the