汶川8.0级与昆仑山口西8.1级地震前地震活动异常特征与启示
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摘要
两次特大地震前在不同时段、不同范围出现了多项相似的地震活动性异常,它们对预测特大地震具有一定意义:①两次大震前10余年,青藏块体同期出现了两个规模巨大的中强以上地震增强区,两次大地震发生在增强区内的空区里;②两次巨大地震前数年,形成规模巨大的中强地震活动带,地震发生在两个条带间的平静区里;同期形成中等以上地震活动环,其内部的地震频度、加卸载响应比及非均匀度等参数甚高,且随时间而变化,这可作为孕震进入中期的信号;③两次大震前的震群、震丛均很显著,昆仑山口西地震前四个显著震丛环绕震中四周分布,汶川地震前震群在震中周围形成包围圈,它们应视为大震孕育进入后期的显示;④大震前数月,靠近发震断裂带发生少量中小地震或少见的震群。汶川地震前10个月,龙门山断裂带北部发生两次青川4级多地震和松潘4.3级地震,南部康定附近发生3次4级以上地震。紫坪铺水库区小震群于震前3个月活动十分强烈。昆仑山口西地震前约1年青海兴海发生6.6级地震,昆仑山口西发生5.1级地震,该地震距离8.1级地震约30 km。这些特征给我们的重要启示是:①特大地震前出现的前兆时空特征与常见的中强地震差异很大,现行的监测预报体制(分省分片负责)与特大地震前兆不相适应;②特大地震的预测预报不能单纯依靠地震前兆,必须与地质构造及深部探测紧密结合起来;③特大地震的预测预报应有新的预报战略、观测系统与组织机构相适应。
Some similar seismic anomalies appeared in different time and different areas before Wenchuan M8.0 and Kunlunshan M8.1 earthquakes,which may bring us some clews to the prediction of large earthquakes.① Two seismic strengthening areas of moderate and large earthquakes formed in Qinghai-Tibet block ten or more years before the two large earthquakes,and the two large earthquakes occurred in the gap in the strengthening area;② Several years prior to the two earthquakes,huge seismic belts of moderate and large earthquakes formed and the two earthquakes took place in the quiescence area between the huge seismic belts.In the same period,there formed a doughnut-shape pattern of M≥4.0 earthquakes,in which the anomalies of earthquake frequency,load/unload response ration and seismic inhomogeneous degree were outstanding and varied with time,these may be clews to the judgment of middle-term earthquake prediction;③ The activity of earthquake swarms and clusters is also outstanding.Four earthquake clusters appeared around the Kunlunshan earthquake and the Wenchuan earthquake occurred in the gap formed by earthquake swarms.These may be signals for judgment of middle-term and short-term earthquake prediction;④ Some small to moderate earthquakes occurred in or near the seismogenic fault zone several months before the two large earthquakes.Ten months prior to Wenchuan earthquake,in the north part of the Longmenshan fault zone,two Qingchuan M≥4.0 shocks and one Songpan M4.3 earthquake occurred,and in the south part,three M≥4.0 earthquakes took place in Kangding and its vicinity,and a small earthquake swarm occurred in Zipingpu reservoir area three months before the Wenchuan earthquake.About one year before Kunlunshan earthquake,a M6.6 earthquake occurred in Xinghai area and a M5.1 shock occurred about 30 km away from the epicenter of Kunlunshan earthquake. The features above may have some implications.① The spatial-temporal characteristics of large earthquakes are different from those of moderately strong earthquakes.The present system of earthquake monitoring and prediction does not suit to the anomaly features of great earthquakes;② Prediction of large earthquakes can not rely singly on seismic precursors and seismic precursors,geological structure and deep exploration should be combined together;③ A new strategy of earthquake prediction,observation and administration should be developed to suit large earthquake predictions.
Some similar seismic anomalies appeared in different time and different areas before Wenchuan M8.0 and Kunlunshan M8.1 earthquakes,which may bring us some clews to the prediction of large earthquakes.① Two seismic strengthening areas of moderate and large earthquakes formed in Qinghai-Tibet block ten or more years before the two large earthquakes,and the two large earthquakes occurred in the gap in the strengthening area;② Several years prior to the two earthquakes,huge seismic belts of moderate and large earthquakes formed and the two earthquakes took place in the quiescence area between the huge seismic belts.In the same period,there formed a doughnut-shape pattern of M≥4.0 earthquakes,in which the anomalies of earthquake frequency,load/unload response ration and seismic inhomogeneous degree were outstanding and varied with time,these may be clews to the judgment of middle-term earthquake prediction;③ The activity of earthquake swarms and clusters is also outstanding.Four earthquake clusters appeared around the Kunlunshan earthquake and the Wenchuan earthquake occurred in the gap formed by earthquake swarms.These may be signals for judgment of middle-term and short-term earthquake prediction;④ Some small to moderate earthquakes occurred in or near the seismogenic fault zone several months before the two large earthquakes.Ten months prior to Wenchuan earthquake,in the north part of the Longmenshan fault zone,two Qingchuan M≥4.0 shocks and one Songpan M4.3 earthquake occurred,and in the south part,three M≥4.0 earthquakes took place in Kangding and its vicinity,and a small earthquake swarm occurred in Zipingpu reservoir area three months before the Wenchuan earthquake.About one year before Kunlunshan earthquake,a M6.6 earthquake occurred in Xinghai area and a M5.1 shock occurred about 30 km away from the epicenter of Kunlunshan earthquake. The features above may have some implications.① The spatial-temporal characteristics of large earthquakes are different from those of moderately strong earthquakes.The present system of earthquake monitoring and prediction does not suit to the anomaly features of great earthquakes;② Prediction of large earthquakes can not rely singly on seismic precursors and seismic precursors,geological structure and deep exploration should be combined together;③ A new strategy of earthquake prediction,observation and administration should be developed to suit large earthquake predictions.
引文
[1]梅世蓉,宋志平,薛艳.中国巨大地震前地震活动环形分布图像与规律[J].地震学报,1996,18(4):413-419.
[2]宋治平,梅世蓉,尹祥础.强大地震前地震活动增强区及其力学研究[J].地震学报,1999,21(3):271-277.
[3]宋治平,薛艳,梅世蓉,等.昆仑山口西8.1级地震的地震活动特征[J].地震,2002,23(1):15-22.
[4]梅世蓉,薛艳.昆仑山口西8.1级地震前的地震活动图像特征[A].中国地震局.纪念南京基准台建台70周年论文集[C].北京:地震出版社:2002.35-40.
[5]国家地震局震害防御司.中国历史强震目录(公元前23世纪—1911年)[M].北京:地震出版社,1995.
[6]中国地震局震害防御司.中国近代地震目录(公元1912年—1990年MS≥4.7)[M].北京:中国科学出版社,1999.
[7]Van der Woerd J,Ryerson F J,Tappomnier-P,et al.Uniform slip-rate along the Kuulun Fault:Im-plications for seismic behaviour and large-scale tectonics[J].Geophysical Research Letters,2000,27(16):23-53.
[8]张培震,王琪,马宗晋.青藏高原现今构造变形特征与GPS速度场[J].地学前缘,2002,9(2):442-450.
[9]张培震,徐锡伟,闻学泽,等.2008年汶川8.0级地震发震断裂带的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1 066-1 073.
[10]薛艳,韩丹.川滇藏缅地区巨大地震危险性分析[A].中国地震局分析预报中心.2004年度地震趋势报告[C].北京:地震出版社,2004.282-287.
[11]李志雄,高旭.地震非均匀度的研究厦在强震中期预报中的应用[J].地震,1994,14(6):11-17.
[12]陆远忠,宋俊高,戴维东.一个判定震群的指标[J].地震学报,1984,6(增刊):495-509.
[13]刘正荣.根据地震频度率减预报地震的工作细则[J].地震,1984,4(1):105-115.
[14]王炜,杨德志.利用Weibull分布研究华北地区前兆震群的特征[J].中国地震,1987,3(4):13-21.
[15]宋俊高,陆远忠,施玉芳.震群用于地震预报的实用程式研究[A].国家地震局科技监测司编,地震预报方法实用化研究文集——地震学专集[C].北京:学术书刊出版社,1989.204-228.
[16]刘蒲雄,郑大林,车时,等.2001年11月14日昆仑山口西8.1级地震前地震活动性异常及其思考[J].地震学报,2003,25(4):205-210.
[17]胡先明.紫坪铺水库蓄水前天然地震活动[J].四川地震,2007,19(2):16-21.
[18]梅世蓉.新形势下地震预报战略问题的探讨[A].中国地震局.中国地震预报探索[C].北京:地震出版社,2008.1-20.
①国家新闻办公室2008年9月4日新闻发布会。
①http://www.csndmc.ac.cn/newweb/
[2]宋治平,梅世蓉,尹祥础.强大地震前地震活动增强区及其力学研究[J].地震学报,1999,21(3):271-277.
[3]宋治平,薛艳,梅世蓉,等.昆仑山口西8.1级地震的地震活动特征[J].地震,2002,23(1):15-22.
[4]梅世蓉,薛艳.昆仑山口西8.1级地震前的地震活动图像特征[A].中国地震局.纪念南京基准台建台70周年论文集[C].北京:地震出版社:2002.35-40.
[5]国家地震局震害防御司.中国历史强震目录(公元前23世纪—1911年)[M].北京:地震出版社,1995.
[6]中国地震局震害防御司.中国近代地震目录(公元1912年—1990年MS≥4.7)[M].北京:中国科学出版社,1999.
[7]Van der Woerd J,Ryerson F J,Tappomnier-P,et al.Uniform slip-rate along the Kuulun Fault:Im-plications for seismic behaviour and large-scale tectonics[J].Geophysical Research Letters,2000,27(16):23-53.
[8]张培震,王琪,马宗晋.青藏高原现今构造变形特征与GPS速度场[J].地学前缘,2002,9(2):442-450.
[9]张培震,徐锡伟,闻学泽,等.2008年汶川8.0级地震发震断裂带的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1 066-1 073.
[10]薛艳,韩丹.川滇藏缅地区巨大地震危险性分析[A].中国地震局分析预报中心.2004年度地震趋势报告[C].北京:地震出版社,2004.282-287.
[11]李志雄,高旭.地震非均匀度的研究厦在强震中期预报中的应用[J].地震,1994,14(6):11-17.
[12]陆远忠,宋俊高,戴维东.一个判定震群的指标[J].地震学报,1984,6(增刊):495-509.
[13]刘正荣.根据地震频度率减预报地震的工作细则[J].地震,1984,4(1):105-115.
[14]王炜,杨德志.利用Weibull分布研究华北地区前兆震群的特征[J].中国地震,1987,3(4):13-21.
[15]宋俊高,陆远忠,施玉芳.震群用于地震预报的实用程式研究[A].国家地震局科技监测司编,地震预报方法实用化研究文集——地震学专集[C].北京:学术书刊出版社,1989.204-228.
[16]刘蒲雄,郑大林,车时,等.2001年11月14日昆仑山口西8.1级地震前地震活动性异常及其思考[J].地震学报,2003,25(4):205-210.
[17]胡先明.紫坪铺水库蓄水前天然地震活动[J].四川地震,2007,19(2):16-21.
[18]梅世蓉.新形势下地震预报战略问题的探讨[A].中国地震局.中国地震预报探索[C].北京:地震出版社,2008.1-20.
①国家新闻办公室2008年9月4日新闻发布会。
①http://www.csndmc.ac.cn/newweb/
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