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Title:: H-value Determination and Strong Aftershock Prediction of Earthquake Sequences in Qinghai Province and its Adjacent Area

Author(s):: MA Ruying; MA Zhen; WANG Peiling; SU Weigang; Earthquake Administration of Qinghai Province,Xining 810001,Qinghai,China

Keywords:: h-value; determination of sequence type; strong aftershock prediction; Qinghai Province and its adjacent area

摘要:: 通过对青海及其周边28组记录相对完备的5.0级以上中强地震序列进行计算,得到各个序列h值随时间的变化趋势。结果显示:所有地震序列h值在主震发生后0～3天内波动变化较大,除个别地震序列外,h值在震后第8天开始趋于稳定; 可根据h值是否大于1快速判定地震序列是否为前震型序列,但由于不同类型地震序列之间h值分布范围重叠较为严重,不能根据h值完全准确地判定出序列类型; 通过h值方法得到最大余震震级的预测结果报准率约为70%(震级误差为±0.5级),余震震级较低时,预测结果相对较为准确,孤立型序列判定结果优于主余型序列; 根据实际发生的地震,检验认为门源6.4级地震序列的发展趋势和最大余震均符合h值预测所得结果。

Abstract:: The h-values of 28 groups of M≥5.0 earthquake sequences which have relatively complete set of records in Qinghai Province and its adjacent area were calculated,and the trend of h-value varied with time were obtained. The results show that the h-value of all the earthquake sequences changed greatly within 0～3 days after the main-shock,and began to stabilize on the 8th day after the main-shock except for the individual earthquake sequences. Based on whether the h-value is greater than 1,we could determine whether the earthquake sequence is a fore-shock sequence. However,due to the overlap of the distribution range of h-value among different types of earthquake,we cannot determine the sequence type according to h-value. The success rate of the prediction of the maximum aftershock magnitude is 70% by h-value method(the error of magnitude is ±0.5). When the magnitude of the aftershock is lower,the prediction result is relatively accurate,and the prediction result of the isolated type sequence is better than that of the main-aftershock type sequence. According to the actual earthquakes,we concluded that the development trend and maximum aftershock of the Menyuan M_S6.4 earthquake sequence are in accordance with the h-value prediction results.