和硕5.0级地震前乌鲁木齐基准地震台钻孔应变异常分析

ABNORMAL ANALYSIS OF DRILL HOLE STRAIN IN URUMQI STATION ABOUT HESHUO EARTHQUAKE WITH MS5.0

运用潮汐因子、加卸载响应比及相对应力场等分析方法,对1995年3月19日发生的新疆和硕MS5.0地震前乌鲁木齐基准地震台钻孔应变观测数据进行了分析处理。结果表明,在地震前30天应变日均值出现了典型的指数曲线异常;在地震前1个月相对应力发生快速变化,主应力方向也发生了快速偏转;全日波潮汐因子地震前1个月到地震前半个月期间,出现了大幅度的单峰或双峰异常变化;加卸载响应比值在地震前2个多月就开始出现成束的异常。可以认为和硕地震前乌鲁木齐基准地震台钻孔应变记录到了明显前兆短临异常。

Using the tide factor, load/unload response ratio, relative stress field and so on analysis methods, we analyzed the observation data of Urumqi drill hole strain before Xinjiang Heshuo earthquake with Ms5.0 on March 19, 1995. The result showed that the daily mean value of strain appeared the typical exponential abnormity curve in 30 day before the earthquake. And in one month before the earthquake, the relative stress appeared the fast change. The direction of principal stress has also had the fast deflection. From one month to half a month before the earthquake, the tide factor of full day-wave appeared large changes of unimodal or multi-modal abnormities. In two months before the earthquake, the load/unload response ratio value started to appear a bundle abnormities. We may think that the drill hole strain of Urumqi recorded the short time abnormity of obvious precursor before Heshuo earthquake.