四川自贡—隆昌地区注水诱发地震研究  

Study on earthquakes induced by water injection in Zigong-Longchang area,Sichuan

作　　者：张致伟 程万正 梁明剑 王晓山[2] 龙锋 许艳 陈文康 王世元 

机构地区：[1]四川l省地震局,成都610041 [2]河北省地震局,石家庄050021 [3]自贡市防震减灾局,自贡643000

出　　处：《地球物理学报》2012年第5期1635-1645,共11页Chinese Journal of Geophysics

基　　金：地震科技星火计划项目(XH1021Y);国家自然科学基金项目(41090294);中国地震局监测预报司震情跟踪定向工作任务(2012020107)联合资助

摘　　要：基于2007年1月—2010年8月四川自贡地方数字测震台网和流动台站记录的地震观测资料,并结合注水井(家33井)的加压注水数据,研究了自贡—隆昌地区三个丛集区域(A、B、C)地震活动与家33井注水压力及注水量的相关性,同时从注水区域及邻区局部应力状态呈现的差异研究其发震机理.结果表明:家33井加压注水对其所在的B区地震活动具有明显的调控作用,负压注水阶段,注水量对地震活动的影响不大,地震活动处于较弱状态;加压注水阶段,在压力持续升高的背景下,地震活动明显增强,其频次、强度与注水量呈现较好的相关性.研究区三次4级地震震源较浅、且均为逆冲型,震源机制节面与其震中附近断层走向一致.基于大量小震震源机制解,统计获得B区震源机制节面走向和P轴方位较A区相对离散;与川东南地区已有应力场结果相比,反演获得的B区主压应力方位较A区扰动偏大,可见在统一应力场的作用下,A、B区域小震震源机制解节面走向、P轴方位及反演得到的局部区域应力场呈现出的差异,与家33井加压注水有一定的关系.Based on seismic data recorded by Zigong local digital seismic network and mobile stations from January 2007 to August 2010, the correlation between pressure, water injection rate of Jia 33 well and seismic activities of three cluster regions （A, B, and C） in ZigongLongchang area is studied, and the seismogenic mechanism of induced earthquakes is studied by the space concentration distribution of shallow seismic activity and the difference of local stress state. The result shows that the injection pressure of Jia 33 well has obvious regulatory effect on seismic activity of region B. At the stage of negative pressure injection, the effect of water injection rate on seismic activity is small, the seismic activity of region B is very weak, at thestage of injection pressure, when the pressure is continuously elevated, the seismicity is obviously increased, and the frequency and intensity present a good correlation with the water injection rate. According to the focal mechanism solutions and stress field characteristic of earthquakes in research area, the focal depth of three ML^4 earthquakes are all shallow, and the dislocation types all present reverse faulting, the strikes of the nodal plane and the fault near epicenter are consistent. Based on a lot of small earthquake focal mechanism solutions, the statistical results of nodal strike and P-axis direction in region B are relatively disperse than the results of region A. Compared with the existing results of regional stress field in the southeast of Sichuan Province, the stress field disturbance of region B is bigger than the result of region A. Under the action of a unified stress field, the nodal and P-axis direction of focal mechanism solutions and stress field in region A and B present difference, which have a certain relationship with injection pressure of Jia 33 well.

关 键 词：诱发地震 加压注水 震源机制解 应力场 自贡-隆昌地区 

分 类 号：P315[天文地球—地震学]