2008年10月5日乌恰6.9级地震背景性异常

Background Anomaly of Wuqia M_s6.9 Earthquake Occurred on Oct.5,2008

分析总结了2008年10月5日乌恰6.9级地震前背景性异常:1900～2008年新疆6.8级以上地震时空分布表明,于田7.4级地震发生后新疆仍缺少一次6.8级以上地震;2004年12月以来新疆3.5级以上地震累积频次持续低值;乌恰地区6级地震超常平静;2003年以来在乌恰地区形成4级地震空区;2006年以来新疆相继形成2条4级地震条带相交于乌恰地区;2006年1月至2008年7月乌恰台地震波振幅比大范围低值:2007年4月至2008年2月,沿卡兹特阿尔特断裂出现2次符合预报指标的异常增强现象:2008年2月以来喀什台地磁垂直分量拟合差值持续低值:2006年9月以来莎车台土层应力2道测值先后出现偏离正常年变现象。

The background anomalies of Wuqia Ms6.9 earthquake occurred on Oct. 5, 2008 were analyzed in this paper, including： the space-time distribution of earthquakes with Ms ≥6.8 from 1900 to 2008 in Xinjiang shows that there is a lack of Ms6.8 earthquake after Yutian MsT.4 earthquake in Xinjiang; the accumulation frequency of earthquakes with Ms≥3.5 continued to be low; Ms6.0 earthquakes is anomaly quiescent in Wuqia region; Ms4.0 seismic gap has come into being in Wuqia region since 2003, while two Ms4.0 seismic belts in Xinjiang has come into being and intersecting in Wuqia region since 2006; the amplitude ratios of seismic wave of Wuqia seismic station show low values in a large range from Jan. 2006 to Jul. 2008; the abnormal phenomenon of seismic activity appeared two times in Kenzitearte fault; the error values of fitted line of vertical geomagnetic component of Kashi station show low values since Feb. 2008; the values of two channels of soil stress in Shache station have successively departed from the annual change value since Sep. 2006.