2006年吉林乾安-前郭M5.0级地震深度及其成因探讨  

Resolving focal depth of the 31 march 2006 Jilin QianAn-QianGuo earthquake with multiple datasets and its implication for seismogenesis

作　　者：高金哲[1,2] 李志伟[3] 包丰[1] 崇加军[1] 

机构地区：[1]中国科学技术大学地球和空间科学学院,合肥230026 [2]吉林省地震局,长春130117 [3]中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室,武汉430077

出　　处：《地球物理学进展》2013年第5期2328-2335,共8页Progress in Geophysics

基　　金：地震科学联合基金(A08116)资助;地震行业科研专项(201308013);国家重点基础研究发展计划(973计划)(2013CB733203)联合资助

摘　　要：2006年3月31日，吉林省乾安与前郭县交界地区发生了M5．0级地震，是吉林省40多年来最大浅源地震，造成了约1亿元的经济损失．有关此次的地震成因有一定争论，而震源深度则是解决这些争论的重要参数之一．鉴于不同机构给出的震源深度差别很大，本文利用吉林省及邻近地区的宽频带数字地震记录和远震波形，采用多种方法准确测定了震源深度．首先采用CAP方法反演近震全波形得到地震的震源机制解，初步确定震源深度为6±1km．利用远震体波波形，通过波形对比和pP深度震相，测定震源深度约为5km．利用流动地震台站观测，测定了14个波形清晰的余震震源深度，大部分余震的震源深度为5～7km．多种震源深度测定结果比较一致，表明乾安地震的震源深度为6±1km．综合地震勘探的资料，表明乾安地震的主震位于基岩之上，在油井下方1～2km．震区历史地震活动性很低，结合油气开采诱发地震的判别标准，推测乾安地震可能与油气开采有关．March 31, 2006, an earthquake with magnitude 5.0 occurred near border of QianAn-QianGuo county of Jilin Province, being the strongest shallow earthquake in the past 40 years in Jilin. It caused about one hundred million＇s RMB economic loss. The earthquake occurred in a region with low historical seismicity, where no M 5 or larger events occurred in the past a few hundred years. As the epicentral region is an oil field with drilling down 3- 4 km in depth, there are some arguments that the earthquake is industry-induced. If it is the case of induced seismicity from oil-gas exploration, the event should be shallow. However, a few seismological agencies report focal depth in the range of 104 15 kin, which are too deep for induced earthquake. To illuminate the possible physical seismogenic processes, we several methods to determine the focal depth with local and teleseimic waveforms. The focal mechanism of the earthquake is inverted with the Cut and Paste method （CAP）, showing focal depth is 6 - 1 km. The focal depth is further confirmed by depth phase pP in teleseismic waveforms, which is about 5 kin. We also relocated 14 aftershocks by temporary seismic observations. The focal depths of aftershocks are at 5-7 km, which is consistent with the result from the above two methods. Together with exploration profile, our results suggests that the QianAn Earthquake is situated above the bedrock, and below the oil-gas drill hole down to 3000- 4000 meters. Due to the shallow focal depth and additional data, we infer the QianAn earthquake is related to the oil and gas exploration, and could be a possible induced earthquake.

关 键 词：乾安地震 震源深度 CAP方法 震源机制解 诱发地震活动 深度震相 

分 类 号：P315[天文地球—地震学]