与2008年汶川M_S8.0地震有关的成都台地电场异常信号

Abnormal signals of geoelectric field related to Wenchuan M_S8.0 earthquake recorded at the Chengdu station

2008年5月12日汶川M_S8.0地震前,位于震源区内的成都台2008年4月10—17日观测到非常强烈的地电场短临异常信号连续不断出现,25天后汶川大地震发生。本文基于地电场多极距原理和2007—2017年10年尺度的地电场观测资料回顾性地检查论证了可能与汶川地震有关的地电场异常前兆。研究结果显示,在与地震有关的强烈电信号中,4月10日23:00至4月11日3:40期间出现的强烈异常信号与4月11日4:00至4月16日12:00出现的40次脉冲信号并非源于同一地点,与4月17日2:00—3:00和22:00—23:00期间的异常信号也不是同源信号。这4个时段出现的大幅异常来自于不同位置的4个区域,暗示着地下的4个应力释放区。最后从机理上对该地电场异常信号进行了可能的解释,认为不同的应力积累区域可能是这些地电场异常信号的源区。由于成都台位于汶川特大地震的震源区内,故此次与地震有关的地电场异常信号可以作为汶川特大地震的孕震物理过程研究的重要参考指标。

The short-term earthquake prediction must be based on reliable precursors,and identifying them from abundant anomalies is the primary problem of earthquake prediction in the world. Before the 12 May 2008 Wenchuan MS8.0 earthquake the very strong abnormal signals of the geoelectric field were observed at Chengdu station,which is located in the range of the focal zone. The signals lasted from April 10 to 17,2008 and twenty five days later the Wenchuan earthquake occurred. This paper demonstrates the geoelectric field precursors related to the shock based on the theorem of the multi-dipole geoelectric field observation and the retrospective check of decade scale data from 2007 to 2017. The study results show that the strong geoelectric anomalies recorded during the four periods,i.e.,from 23：00 on April 10 to3：40 on April 11,from 4：00 on April 11 to 12：00 on April 16,2：00-3：00 and 22：00-23：00 on April 17,originated respectively from four different sources,in which the second set of signals consists of forty pulses,which means that there were four stress concentration and release regions in the focal zone. The reasonable mechanism explanation to the abnormal signals is also given in the paper in which different stress concentration regions are considered as the sources of them. Because Chengdu station is located in the focal zone of the Wenchuan earthquake,the anomalies could be taken as one of the important reference indices for researches on the preparation processes of an earthquake.