甘川交界地区近年地震活动与武都地震台前兆资料变化特征

The Variation Characteristics of Precousor Data in Wudu Seismic Station and the Earthquake Activity in the Boundary Area between Gansu and Sichuan Province in Recent Years

摘要:

位于甘川交界地区的武都地震台在2003-2008年5月4次中强地震前前兆资料出现了明显异常变化。主要表现为:武都应变的南北向张应力在2001-2005年间持续增强,2007年转折后4个测向都表现为受压,且快速增强,在高压应力持续7个月后发生汶川8.0级大震;地电阻率显示了长趋势变化的加速、转折和1年尺度上升、下降等异常,各向异性度S'年变化率在有震年(异常年)是无震年(正常年)的两倍;自然电场在临震前变化具有相似性、重复性、同步性。

Abstract:

Wudu seismic station is located in the boundary area between Gansu and Sichuan provinces. From 2003 to May 2008, before four moderate-strong earthquakes in this area, the observation data from Wudu station had significant precursor anomalies. It mainly showed as follows： the tensile stress in NS direction had been sustained increasing from 2001 to 2005, then turned to compression in four directions in 2007, and repidly increased. After this high-pressure stress kept seven months, the Wenchuang M8.0 earthquake occurred. The earth resistivity data showed the long trend of acceleration and changing, with increasing, descending etc. anomalies in a year scale. The annual variation ratio of the anistropic index S is two times in earthquake occurring years （anomaly years） than in quiet years. The variation of natural electric field had likeness, repeatability and similarity in imminent earthquake period.