芦山M_S 7.0地震前地震活动性分析及区域地震活动水平参数I_(RTL)的应用  

Seismicity changes prior to the M_S 7.0 Lushan earthquake and the application of regional seismic activity parameter I_(RTL)

作　　者：刘月[1] 吕晓健[1] 田勤俭[1] LIU Yue LU Xiaojian TIAN Qiniian(Key Laboratory of Earthquake Prediction China Earthquake Administration, Institute of Earthquake Science, China Earthquake Adminis tration, Beijing 100036, China)

机构地区：[1]中国地震局地震预测研究所中国地震局地震预测重点实验室,北京100036

出　　处：《地学前缘》2017年第2期220-226,共7页Earth Science Frontiers

基　　金：中俄科技合作专项"基于地震活动性资料的地震预测方法研究"(2012DFR20440K05)

摘　　要：本文采用Region-Time-Length(RTL)方法分析在汶川M_S 8.0级地震引起的地震活动增强背景下芦山M_S 7.0地震前地震活动性变化,并提出了综合反映区域地震活动水平的参数IRTL。芦山地震前1年在震中和周边地区检测到地震活动平静异常,主要分布在龙门山断裂带南段1.5°N×2°E范围内,持续了近8个月,异常范围和异常程度呈现由小→大→小的特征。新提出的区域地震活动水平参数I_(RTL),早期在0值附近波动,于震前一年开始不断下降,降至波谷后回升到较低值,波谷后9个月发震。I_(RTL)在一定程度上为"识别"芦山地震发生危险性提供了参考。以上研究对了解芦山地震孕育过程提供了新的认识。An analysis of the characteristics of seismicity changes prior to the M_S7.0 Lushan earthquake which was under the influence of increased seismic activity caused by M_S8.0 Wenchuan earthquake was conducted and a new physical parameter IRTL was proposed to comprehensively evaluate the space-time changes of seismicity of a region.One year prior to the earthquake occurrence,seismic quiescence was detected in epicenter and surrounding areas.Anomalies mainly distributed in the southern segment of the Longmenshan thrust belt within the range of 1.5°N×2°E,which had lasted for nearly 8 months.The area of abnormal region and the degree of quiescence were changed from small to large and then to small again chronologically.The new parameter I_（RTL） could evaluate regional seismicity anomalies in space and time.At early stage,I_（RTL） fluctuated around zero,and then fall to the trough.Prior to the earthquake occurrence,I_（RTL） went back to a small value again.Nine months after the trough,Lushan earthquake occurred.IRTLcould provide some evidence to evaluate the risk of Lushan earthquake occurrence.This study may give better understanding of the seismogenic process of Lushan earthquake.

关 键 词：芦山MS 7.0地震 RTL算法 地震活动性 区域地震活动水平参数 

分 类 号：P315[天文地球—地震学]