青藏块体东北缘中强地震前小震频度异常研究  

Anomaly of Small Earthquake Activities before Medium to Strong Earthquakes in the Northeast Margin of the Qinhai-Tibet Block

作　　者：冯建刚[1] 周龙泉[2] 杨立明[1] 代炜[1] 

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州730000 [2]中国地震台网中心,北京100045

出　　处：《地震》2009年第3期19-26,共8页Earthquake

基　　金：地震行业科研专项资助(200708038);国家科技支撑计划(2006BAC01B03-04-02)联合资助

摘　　要：1980年以来青藏块体东北缘共发生26次MS5.0以上地震,其中22次在时间和空间上相对独立。通过系统研究这22次中强地震前其邻区小震活动的增强现象,发现有17次中强地震前存在比较明显的小震增强现象。虽然小震增强现象在多数中强地震前存在,但是利用小震活动的增强对未来中强地震的预测比较困难。文中结合青藏块体东北缘小震活动的特点,尝试提出根据小震活动空间格局是否改变统计小震频度的方法,并且进行了初步的应用。结果表明:利用新方法统计小震的频度更能突出中强地震前的小震频度异常,并且中强地震前的小震频度异常幅度受空间范围大小的影响不大,能够有效的提取青藏块体东北缘中强地震前的中短期异常指标。26 Ms≥5.0 earthquakes were recorded in the northeast margin of Qinghai-Tibet block since 1980, in which 22 medium-strong earthquakes are independent in space and time. Study of seismicity increasing before the 22 medium-strong earthquakes shows that small earthquakes increasing occurred before 17 medium-strong earthquakes. Though seismicity increasing is a common phenomenon in the northeast margin of Qinghai-Tibet block, we have difficulty in predicting the medium-strong earthquakes by this phenomenon alone. In order to predict the medium-strong earthquakes through seismicity increasing, this paper tries to propose a new method which calculate small earthquake frequency through the changing pattern of small earthquake activities based on the character of small earthquake activity in the northeast Qinghai-Tibet block and then make primary application, the result showed that we can get obvious anomaly frequency of small earthquake before medium strong earthquake through the new method, and it is affected very little from the range of area where small earthquakes occurred. We can get medium to short term anomaly index in the northeast margin of Qinghai-Tibet block .

关 键 词：中强地震 青藏块体东北缘 小震活动 中短期异常 

分 类 号：P315[天文地球—地震学]