【摘要】 2011年3月11日日本发生9.0级地震,本文以此次地震的震间、同震和震后形变观测为约束,依据不同时段断层运动空间分布特征分析日本海沟地区强震与断层运动间关系.震间日本海沟地区,断层运动闭锁线深度约为60km,闭锁线以上从深到浅依次为断层运动强闭锁段、无震滑移段和弱闭锁段.由同震位错反演结果,2011年日本9.0级地震同震存在深浅两个滑移极值区,同震较浅的滑移极值区(同震位错量10~50m,深度小于30km)震间为断层弱闭锁段;同震较深的滑移极值区(同震位错量10~20m,深度在40km左右)震间为断层强闭锁段;而在两者之间的过渡带同震位错相对较小,震间断层运动表现为无震滑移.震后初期断层运动主要分布在在闭锁线以上的同震较深滑移极值区,而同震较浅的滑移极值区能量释放比较彻底,断层震后余滑量相对较小.依据本文同震和震间断层运动反演结果,震间强闭锁段积累10m同震位错需要100多年时间,与该区域历史上7级地震活动复发周期相当;震间弱闭锁段积累30~50m同震位错约需要300~600年时间,与相关研究给出的日本海沟9级左右地震复发周期比较一致.在实际孕震能力判定的工作中,由于不同性质的断层段在同震过程中会表现更多的组合形式,断层发震能力判定结果存在更多的不确定性,但利用区域形变观测等资料给出震间断层运动特征的研究工作对于断层强震发震能力的判定具有非常重要的实际意义.更多还原

【Abstract】 For the Mw9.0earthquake occurred in the Japan trench on March 11,2011,this paperused the constraints from the inter-seismic,co-seismic,and post-seismic deformation observations,and analyzed the relationship between the strong earthquake in the Japan trench and the fault movement according to the spatial distribution characteristics of the fault movement at different times.Based on crustal deformation observation,we study the 3Dspatial distribution characteristics of inter-seismic,co-seismic,and post-seismic fault movement and provide the pattern diagram of fault motion at the trench areas of Japan.We invert the coseismic displacements of the fault based on uniform fault model(oblique fault model,the dip from the seabed to 50 km depth changes from 5degrees to 20 degrees,the unified strike 198)and 3Dfault model(seismic parameters of the 3Dfault model are given by fitting).The results show that,as for the 3Dfault model,the coseismic dislocations better fit the data,and more agree with fault properties.Therefore,in carrying out the work of similar inversion accuracy of fault geometry,the reliability of the results is very important.The inversion results show that there are two coseismic slip extreme areas.The maximum coseismic dislocation is about 50 m,located in the shallower coseismic slip extreme area.The dislocation amount of the coseismic rupture is greater than 10 mnear the epicenter in a range of 400km;in the South Japan Trench the coseismic displacement is relatively small,the earthquake is a typical Japan trench thrust type earthquakes.According to the spatial distribution characteristics of the magnitude 9.0 earthquake and the previous strong earthquake ruptures in the area,the magnitude 9earthquake rupture bore the characteristics of recurrence of strong earthquake,and was the strong earthquake rupture to fill in the gaps.In inter-seismic stage in the Japan trench,the depth of the locking line is about 60 km,moreover,the fault movement,from deep to shallow above the locking line,in order,is strong locking,aseismic slip,weak locking.From coseismic dislocation inversion,there are two coseismic slip extreme areas.The shallow one(coseismic displacement 10~50m,depth less than 30km)is weak locking before this earthquake;and the deep one(coseismic displacement 10~20 m,depth about 40km)is strong locking before this earthquake;and the coseismic dislocation in transition zone between with extreme coseismic slip areas is relatively small and there is aseismic slip before this eartqhuake.In the initial period after the earthquake,afterslip is mainly in the deeper coseismic extreme slip areas.On the basis of the coseismic and interseismic fault motion inversion results,the seismic strong locked segment will take 100 years to accumulate 10 m coseismic dislocation,and the regional history has 7earthquake recurrence periods of earthquake activity;the weak locked segment will take about 300~600years to accumulate 30~50mcoseismic dislocation,which is consistent with the recurrence period of magnitude 9.0earthquake in Japan Trench given by relevant research.As to determining the actual seismogenic ability,because the different sections of one fault will form more combinations in the earthquake process,fault earthquake capacity determination result is more uncertain.But the research on regional deformation observation data is very important and of practical significance for judging fault strong earthquake ability.更多还原