利用重复地震估算北京平原地区隐伏断裂深部的活动速率  

SLIP RATES AT DEPTH ALONG THE BURIED FAULTS IN BEIJING PLAIN AREA ETSTIMATED FROM REPEATING MICROEARTHQUAKES

作　　者：李乐[1] 陈棋福[1] 

机构地区：[1]中国地震局地震预测研究所,北京100036

出　　处：《地震地质》2010年第3期508-519,共12页Seismology and Geology

基　　金：中国地震局地震预测研究所基本科研业务专项(02092405)资助

摘　　要：利用首都圈数字化地震台网2001—2006年的波形资料分析北京平原地区隐伏断裂的深部滑动速率。通过波形互相关分析,识别出35组相似地震对和20组多重相似对,大部分相似地震活动表现为非周期性,重复间隔从数分钟到数百天不等。针对研究区内台站分布稀疏和低信噪比波形记录的现状,在波形相似的基础上,提出了采用在子采样条件下的S-P相对到时差(dSmP)和相对到时拾取误差来对相似地震震源位置的一致性进行强约束,进一步探索和完善波形意义上重复地震的识别方法。基于4组"重复地震"估算北京平原区黄庄-高丽营断裂和南口-孙河断裂在不同孕震深度处的滑动速率为1.0～1.2mm/a,怀安镇盆地南缘断裂地表以下9.4km处的滑动速率估计值为1.5mm/a,这一结果和地质资料结果相符。Slip rates along the buried faults in Beijing plain area were investigated with the seismic waveform data between 2001 and 2006 recorded by the Beijing Digital Seismic Network. Using cross- correlation analysis of available waveforms,we identified a total of 35 doublets and 20 muhiplets that show high waveform similarity. Most of these sequences are aperiodic with recurrence intervals varying from a few minutes to hundreds of days. Given the limited quantity and quality of seismic data in the study area,we have chosen a more robust approach to constrain repeated event locations. The approach incorporates both seismogram similarity by requiring cross correlation threshold and location similarity by requiring differential S-P （dSmP）time between events pairs to be small and minor internal inconsistence in travel time picking at sub-sample precision. The composite selection approach improves the identification of repeating earthquake based on similarity in waveforms. Based on four repeating sequences, we obtained the slip rate about 1.0 ~ 1.2mm/a at seismogenic depths of Hangzhuang-Gaoliying Fault and Nankou-Sunhe Fault,and the slip rate of 1.5mm/a at 9.4km of the south boundary fault of Huai＇an Basin,which is consistent with geological and geodetic measurements.

关 键 词：隐伏断裂 重复地震 滑动速率 北京平原地区 

分 类 号：P315.2[天文地球—地震学]