芦山M7.0级与汶川M8.0级地震前兆异常对比
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摘要
清理了芦山M7.0级地震和汶川M8.0级地震前四川报告的前兆异常资料。两次强震前,地震活动性资料显示,龙门山断裂南段、鲜水河断裂南段至三岔口地区、华蓥山断裂附近至宁南—巧家、盐源—宁蒗—永胜一带中小地震活动相对活跃;在四川及邻区,ML≥2.5级地震的地震活动因子A值、地震空间集中度C值和地震危险度D值都处于相对高值;长宁、珙县地区中等地震视应力偏高,芦山地震震中附近视应力偏高。芦山地震前以流动形变异常为多,中短期异常突出,异常幅度大,异常时间集中。汶川地震前,前兆异常以地下流体为多,中期异常居多,但异常幅度小且异常时间相对分散。两次强震前异常台项比相似,宏观异常出现在震前3个月时间范围内,汶川地震前的宏观异常项目数多于芦山地震前的。
We collect the observation data to try to find the possible seismic precursors before both the 2008 M8. 0Wenchuan and the 2013 M7. 0 Lushan Earthquakes. Before two earthquakes,the seismicity intensity grew stronger along four seismic belts,the south segment of Longmenshan faults,from the southern part of Xianshuihe fault to Shimian,from Huayinshan to Qiaojia and Yuanyan-Ninglang-Yongshen Seismic faults. Around Sichuan region,the factor A-value of seismicity,the C-value of space-concentrating and the D-value of seismic risk were high. The apparent stress values calculated for Changning and Gongxian counties were high and the apparent stress calculated for Lushan County was high as well. Among the possible seismic precursory items,the main items were from the crust deformation observation. The middle-and short-term precursory items were main parts of precursory items.Before the 2008 M8. 0 Wenchuan Earthquake among the possible seismic precursory item numbers come from the groundwater contents observation and were the middle-term attribute. The macro-precursory item number of the2008 M8. 0 Wenchuan Earthquake is bigger than those of the 2013 M7. 0 Lushan Earthquake three months before these two earthquakes.
引文
[1]杜方,龙锋,阮祥,等.四川芦山7.0级地震及其与汶川8.0级地震的关系[J].地球物理学报,2013,56(5).
    [2]程万正.汶川地震与松潘地震前异常现象分析比较[J].四川地震,2012(1).
    [3]程万正,官致君,苏琴,阮祥,张致伟.汶川Ms8.0地震前四川地区前兆异常及其统计分析[J].地震学报,2011(3).

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