芦山M_S7.0地震前近震源区地形变熵特征研究

Research on anomalous crustal deformation entropy in near-field before the Lushan M_S7.0 earthquake

2013年4月20日芦山MS7.0地震是继2008年汶川MS8.0地震后发生在龙门山断裂带的又一强震,与汶川地震相似,该震临震前在近震源区未观测到显著的异常变化。为研究其临震前形变特征,本文根据信息熵理论对芦山MS7.0地震前近震源区的连续形变观测资料进行了年变熵率值分析,并研究其时序上的分布特征。结果表明,震前近震源区台站地倾斜形变熵均表现出减熵现象,时序的年尺度熵结果表明,汶川MS8.0地震对芦山MS7.0地震具有一定的触发作用,且震中区的EW向和NS向分量具有高度一致的熵变趋势。

The Lushan MS7. 0 earthquake on May 5,2013 in Sichuan Province is another strong earthquake occurring in the Longmenshan fault zone following the Wenchuan MS8. 0 earthquake in2008. The similarity between the both is that there is no noteworthy anomalous change. In order to study the deformation pattern prior to the earthquake,this paper processes the continuous observation data in the near-source area to calculate annual-entropy and analyze its distribution characteristics in time series based on the entropy theory. The results showed that the earth tilt in near-source area decreases obviously before the Lushan earthquake,and the time sequential annual-entropy showed that the Wenchuan MS8. 0 earthquake had a trigger action on the Lushan MS7. 0 earthquake,and the entropy variation trend of EW direction is in high accordance with that of NS direction.