临夏地震台观测到的临震预滑和震颤震相

Observation of Pre-slip and Tremor Seismic Phase at Linxia Seismic Station

对临夏地震台的YRY-4分量应变仪、水位仪和地震仪记录数据分析后发现:2008年5月12日汶川M_(W)7.9地震前,在3种不同学科的观测记录上,在相近时间段内均记录到了预滑震相Xp和震颤震相Tp。总结Xp震相和Tp震相记录特征的基础上,试图用实验室做的小尺度黏滑实验结果来佐证和解释所记录到的临震预滑和震颤震相的物理机制。结果表明:临震前的2008年4月18日和5月6日,临夏台所处的地块发生了2次较大幅度的预滑错动,在预滑发生前后还伴有N次震颤现象发生。临震前这2次较大幅度的预滑错动有可能引发了汶川M_(W)7.9地震。

Through the analysis of the data recorded by the Yry-4 component strain gauge,the water level gauge,and the seismograph at Linxia seismic station,it is found that before the Wenchuan M_(W)7.9 earthquake on May 12,2008,both of the pre-slip seismic phase Xp and the tremor seismic phase Tp were recorded by the above three instruments in a similar period.In this paper,based on the summary of the record characteristics of Xp and Tp phases,the physical mechanism of pre-slip and tremor phase recorded before the earthquake was confirmed and explained by the results of indoor small-scale stick slip experiments.The results showed that:on April 18 and May 6,2008,two large-scale pre-slip dislocations occurred on the block where Linxia station is located,and N tremors were accompanied before and after the pre-slip.These two large-scale pre-slip dislocations may be related with the Wenchuan M_(W)7.9 earthquake.