2011年日本MW9.0地震相关研究综述  

Review on Researches Associated with the 2011 M_W9.0 Tohoku-Oki Earthquake

作　　者：邵志刚[1] 王芃[1] 李海艳[1] 

机构地区：[1]中国地震局地震预测研究所,中国地震局地震预测重点实验室,北京100036

出　　处：《地震》2016年第4期1-21,共21页Earthquake

基　　金：地震行业专项(201408019);基本科研业务项目(2016IES0301)联合资助

摘　　要：2011年3月11日,日本海沟发生的9级地震造成重大人员伤亡,受到社会普遍关注,本文基于此次日本9级地震相关研究结果,尝试从不同侧面分析此次地震的观测、现象和认识,主要包括如下几点:1此次地震发生在太平洋板块西北边界上日本海沟俯冲带上,同震破裂可能存在深浅两个位错集中区,较深的位错集中区位错量相对较小,但历史上7级地震多发;而较浅的位错集中区位错较大,但历史上强震活动相对较弱;2基于GPS观测资料为约束的相关断层运动研究结果表明,日本海沟断层运动背景以大范围稳定闭锁为主(闭锁区空间尺度与同震破裂尺度相当),自2003年日本北海道8级地震后日本海沟地区断层运动开始出现扰动,2008年以后有几次7级左右地震震后余滑分布明显比主震位错量要大,之后分别于2008年和2011年观测到显著慢滑移事件,最后分别于2011年3月9日和3月11日发生7级前震和9级主震,震前日本海沟俯冲带断层运动变化过程比较清楚;3可能是由于监测的原因,传统上的前兆观测并未出现显著异常,其震前异常主要为:部分地震活动参数表明强震震源区震前应力状态相对较高、区域地表运动速率的短期异常等;4对于震源区物理性质的分析引起了更多的科学问题,例如,震源区介质物性是否与周边存在显著差异、断层摩擦性质是否决定了发震能力和破裂过程、震前断层运动是否存在预滑、震前深部流体是否影响到震源区断层运动等。他山之石可以攻玉,希望本文对地震预测预报基础研究工作能起到抛砖引玉的作用。On March 11,2011,an M_S9 earthquake occurred in the trench near Japan,caused tremendous casualty and attracted extensive concern.Based on results of related researches,this paper analyzed observations,phenomena and understandings of the earthquake from varied aspects,and obtained four main conclusions.① The earthquake located in the northwest boundary of the pacific plate,and has two zones of concentrated coseismic slip at different depths,with relatively small slip in the deep zone where it experienced many M7 historical earthquakes,and large slip in the shallow zone where it has few historical strong earthquakes.② Studies of fault movement constrained by GPS data show that fault movement in the Japan trench has a background of widely distributed stability and locking（area of locking zone is equivalent to that of coseismic ruputure zone）,perturbation occurred after the 2008 Hokkaido M8 earthquake,several-M7has afterslip lager than coseimic slip,two obvious slow slip events was recorded in 2008 and 2011,eventually,the March 9,2011 M7 foreshock and the March 11,2011 M9 mainshock occurred.The pre-earthquake changing of the fault movement in Japan Trench is quite clear.③ Possibly due to monitoring reason,traditional precursory observations show no obvious anomaly.Anomaly before earthquake consists of high stress state in focal zone reflected by some seismic activity parameters,short period anomaly in regional ground motion,etc.④Analysis of physical property in focal zone aroused more scientific issues,for example,is there obvious difference between physical property in focal zone and its vicinity？Does frictional property of fault determine seismogenic ability and rupture process？Whether preearthquake fault movement include pre-slip？Could deep fluid affect fault movement in focal zone？Experience is the best teacher,and the authors hope this paper could be a modest spur to induce others in basic research in earthquake forecast and prediction.

关 键 词：日本Mw9.0地震 地震预报 地震监测 地震研究 

分 类 号：P315.7[天文地球—地震学]