汶川8.0级地震及强余震破裂方式与引潮力之间的关系
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摘要
本文通过计算汶川8.0级主震及20次MS≥5.0强余震发震时刻引潮力的方位、大小及变化率,并对比其破裂方式,发现11次逆冲型地震其发震时刻的水平引潮力方位和主压应力轴P轴有6次夹角在33°之内;8次走滑型地震,其发震时刻垂向引潮力都处于向上的峰值区间;而2次具有张性正断分量的地震,发震时刻垂向引潮力都处于向下的峰值区间。根据以上的统计特征,本文就引潮力对三种破裂类型在汶川主震及强余震中可能的触发机制进行了探讨。
By calculating the azimuth,phase angle and change rate of tide force at the times of occurrences of the Wenchan MS8.0 earthquake and 20 MS≥5.0 aftershocks,and contrasting with their rupture types,we find that the angles between the direction of the horizontal tidal and compressive principal stress are within 33° for 6 earthquakes in 11 reverse earthquakes.All of the vertical phase angles of 8 strike-slip earthquakes are in the up peak period,and 2 normal earthquakes′ vertical phase angles are in the downward peak.Based on statistical phenomenon,we discussed the mechanism of tidal force triggering of the Wenchuan MS8.0 Earthquake and its strong aftershocks.
By calculating the azimuth,phase angle and change rate of tide force at the times of occurrences of the Wenchan MS8.0 earthquake and 20 MS≥5.0 aftershocks,and contrasting with their rupture types,we find that the angles between the direction of the horizontal tidal and compressive principal stress are within 33° for 6 earthquakes in 11 reverse earthquakes.All of the vertical phase angles of 8 strike-slip earthquakes are in the up peak period,and 2 normal earthquakes′ vertical phase angles are in the downward peak.Based on statistical phenomenon,we discussed the mechanism of tidal force triggering of the Wenchuan MS8.0 Earthquake and its strong aftershocks.
引文
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[2]Tanaka S,Ohtake M,Sato H.Spatio-temporal variation of the tidal triggering effect on earthquakeoccurrence associated with the 1982 South Tonga earthquake ofMW7.5[J].Geophys Res Lett,2002a,29(16):1 756,doi:10.1029/2002GL015386.
[3]Tanaka S,Ohtake M,Sato H.Evidence for tidal triggering of earthquakes as revealed from statisti-cal analysis of global data[J].J Geophys Res,2002b,107(B10):2 211,doi:10.1029/2001JB001577.
[4]张国民,李丽,黎凯武,等.强震成组活动与潮汐力调制触发[J].中国地震,2001,17(2):110-120.
[5]李延兴,许力生,胡新康,等.日月对孕震区的水平引潮力与震源机制的关系[J].地震,2001,21(1):2-6.
[6]陈荣华.引潮力对显著地震的触发作用与大震关系及在雅江地震预报中的应用[J].地震,2003,23(1):53-56.
[7]吴小平,黄雍,胡家富,等.地震主应力方向的附加潮汐应力计算及其对发震断层的作用方式研究[J].地震研究,2001,24(1):48-54.
[8]张晶,郗钦文,杨林章,等.引潮力与潮汐应力对强震触发的研究[J].地球物理学报,2007,50(1):448-454.
[9]蒋海昆,黎明晓,吴琼,等.汶川8.0级地震序列及相关问题讨论[J].地震地质,2008,30(3):746-757.
[10]胡幸平,俞春泉,陶开,等.利用P波初动资料求解汶川地震及其强余震震源机制解[J].地球物理学报,2008,51(6):1 711-1 718.
[2]Tanaka S,Ohtake M,Sato H.Spatio-temporal variation of the tidal triggering effect on earthquakeoccurrence associated with the 1982 South Tonga earthquake ofMW7.5[J].Geophys Res Lett,2002a,29(16):1 756,doi:10.1029/2002GL015386.
[3]Tanaka S,Ohtake M,Sato H.Evidence for tidal triggering of earthquakes as revealed from statisti-cal analysis of global data[J].J Geophys Res,2002b,107(B10):2 211,doi:10.1029/2001JB001577.
[4]张国民,李丽,黎凯武,等.强震成组活动与潮汐力调制触发[J].中国地震,2001,17(2):110-120.
[5]李延兴,许力生,胡新康,等.日月对孕震区的水平引潮力与震源机制的关系[J].地震,2001,21(1):2-6.
[6]陈荣华.引潮力对显著地震的触发作用与大震关系及在雅江地震预报中的应用[J].地震,2003,23(1):53-56.
[7]吴小平,黄雍,胡家富,等.地震主应力方向的附加潮汐应力计算及其对发震断层的作用方式研究[J].地震研究,2001,24(1):48-54.
[8]张晶,郗钦文,杨林章,等.引潮力与潮汐应力对强震触发的研究[J].地球物理学报,2007,50(1):448-454.
[9]蒋海昆,黎明晓,吴琼,等.汶川8.0级地震序列及相关问题讨论[J].地震地质,2008,30(3):746-757.
[10]胡幸平,俞春泉,陶开,等.利用P波初动资料求解汶川地震及其强余震震源机制解[J].地球物理学报,2008,51(6):1 711-1 718.
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