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  

Anomalous Seismic Characteristics before Wenchuan M8.0 and Kunlunshan M8.1 Earthquakes and Their Implications

作　　者：梅世蓉[1] 薛艳[2] 宋治平[3] 

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地震台网中心,北京100045 [3]上海市地震局,上海200062

出　　处：《地震》2009年第1期I0001-I0001,1-14,共15页Earthquake

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 differe

关 键 词：地震增强区 地震活动环 平静区 地震条带 地震空区 震群 震丛 

分 类 号：P315.7[天文地球—地震学]