科氏力对中国大陆地区M_S≥7.0地震强余震的影响分析
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摘要
利用1966—2017年中国大陆地区发生的28次M_S≥7.0地震资料,在仅考虑科氏力在断层面外法线方向的投影分量F_n的基础上分析了余震与受到的科氏力之间的关系。F_n>0表明科氏力使断层面松弛,将减小断层面上的摩擦力,有利于断层面错动并释放能量,余震的强度较小;反之,余震的强度较大。结果表明:15次F_n>0的地震中,有14次地震的主-余震震级差ΔM≥0.8,占93.3%;而13次F_n<0的地震中,只有5次地震的主-余震震级差ΔM<0.8,占38.46%。根据符号检验法可知,当F_n>0时,发生地震的主-余震震级差ΔM≥0.8具有显著性,在α=0.01显著性水平下通过显著性检验。因此,在实际地震趋势判定工作中,利用F_n>0对地震的余震进行判定将更为可靠。
The relationship between the occurrence of 28 M_S≥7.0 earthquakes in the China Mainland during the period from 1966 to 2017 and the Coriolis force caused on their fault planes was analyzed.The normal component F_n of the Coriolis force on the fault plane was only considered in the analysis.When F_n>0,it shows that the Coriolis force will make the fault plane relax,and reduce the friction on the fault plane,beneficial to the dislocation and energy release of the fault plane.In this situation the magnitude of aftershock could be weaker.Otherwise,the magnitude of aftershock could be stronger.The results are as follows:Among the 28 M_S≥7.0 earthquakes,there are 15 events for F_n>0 and 13 events for F_n<0.Further analysis shows that among the 15 earthquakes for F_n>0,there are 14 events for the magnitude difference between mainshock and aftershock ΔM≥0.8 with a percent of 93.3%,and among 13 earthquakes for F_n<0,there are only 5 events for the magnitude difference between mainshock and aftershock ΔM<0.8 with a percent of 38.46%.According to sign test,for the earthquakes that occur when F_n>0,the possibility of ΔM≥0.8 could be larger with a significant correlation(α=0.01).Therefore,it is more reliable in practice to predict the maximum magnitude of aftershock when F_n>0.
The relationship between the occurrence of 28 M_S≥7.0 earthquakes in the China Mainland during the period from 1966 to 2017 and the Coriolis force caused on their fault planes was analyzed.The normal component F_n of the Coriolis force on the fault plane was only considered in the analysis.When F_n>0,it shows that the Coriolis force will make the fault plane relax,and reduce the friction on the fault plane,beneficial to the dislocation and energy release of the fault plane.In this situation the magnitude of aftershock could be weaker.Otherwise,the magnitude of aftershock could be stronger.The results are as follows:Among the 28 M_S≥7.0 earthquakes,there are 15 events for F_n>0 and 13 events for F_n<0.Further analysis shows that among the 15 earthquakes for F_n>0,there are 14 events for the magnitude difference between mainshock and aftershock ΔM≥0.8 with a percent of 93.3%,and among 13 earthquakes for F_n<0,there are only 5 events for the magnitude difference between mainshock and aftershock ΔM<0.8 with a percent of 38.46%.According to sign test,for the earthquakes that occur when F_n>0,the possibility of ΔM≥0.8 could be larger with a significant correlation(α=0.01).Therefore,it is more reliable in practice to predict the maximum magnitude of aftershock when F_n>0.
引文
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吕坚,高建华,刘吉夫,等.2003.有关科里奥利力效应与昆仑山口西8.1级地震余震活动趋势的讨论[J].地震学报,25(4):432-440.
吕坚,张小涛,马广庆,等.2006.西部及邻区两次强震序列的震级特征及其力学解释[J].中国地震,22(4):435-438.
盛书中,万永革,田力.2009.科里奥利力对断层作用的统计研究[J].中国地震,25(3):256-264.
郭安宁,陈家超.1998a.科里奥利力效应及对强余震预报方法的研究(一)[J].高原地震,10(2):26-34.
郭安宁,陈家超.1998b.科里奥利力效应及对强余震预报方法的研究(二)[J].高原地震,10(3):23-29.
郭安宁,陈家超.1998c.科里奥利力效应及对强余震预报方法的研究(三)[J].高原地震,10(4):28-34.
郭安宁,郭增建,任栋,等.2015.地震破裂的科里奥利力的余震效应在中国大陆外的震例研究及普适性讨论[J].地震工程学报,37(增刊1):86-90.
郭增建,郭安宁.2009.关于用科氏力预测最大余震问题的讨论[J].中国地震,25(4):432-435.
郭增建,秦保燕,李革平.1992.未来灾害学[M].北京:地震出版社.
郭增建,吴瑾冰.2001.用Corioli力讨论台湾南投7.6级大震的余震强度[J].灾害学,16(1):35-38.
郭增建.2012a.水平面上处理科氏力余震效应[J].山西地震,(1):1-4
郭增建.2012b.水平面上处理科氏力余震效应(续一)[J].山西地震,(3):1-3
郭增建.2012c.水平面上处理科氏力余震效应(续二)[J].山西地震,(4):8-11.
郭增建,郭安宁,张炜超,等.2012d.科氏力余震效应在地震救援中的意义[J].国际地震动态,(12):16-23.
李少梅.2013.科氏力在强余震预报中的应用[J].环境科技,42(1):68-69.
吕坚,高建华,刘吉夫,等.2003.有关科里奥利力效应与昆仑山口西8.1级地震余震活动趋势的讨论[J].地震学报,25(4):432-440.
吕坚,张小涛,马广庆,等.2006.西部及邻区两次强震序列的震级特征及其力学解释[J].中国地震,22(4):435-438.
盛书中,万永革,田力.2009.科里奥利力对断层作用的统计研究[J].中国地震,25(3):256-264.