日本MW9.0地震震区及其周缘2002—2015年卫星重力变化时空特征

本文在考虑全球陆面数据同化系统陆地水储量变化影响后，利用2002年4月—2015年4月GRACE卫星RL05月重力场模型获取了2011年日本M_W9.0地震震中及其周边区域的重力场信息；然后给出了日本及其周边2003—2015年的年度累积重力变化和差分重力变化，并且利用经验正态函数方法深入分析了该地震过程中同震重力变化对区域重力场的贡献. 结果显示:日本M_W9.0地震前研究区域出现了幅值高达2×10-8 m/s2的异常重力变化，其同震效应的时间和空间特征均出现在第一模态，且同震重力变化和震后区域重力场变化特征显著，这充分表明该地震对区域重力场的影响显著. 

Spatial and temporal characteristics of long-term satellite gravity change in the epicenter of MW9.0 Japan earthquake and its surrounding regions

Considering the contribution of terrestrial water storage from global land data assimilation system to gravity changes, we use the temporal gravity filed models of GRACE from April 2002 to April 2015 to calculate regional gravity changes in the epicenter of M_W9.0 Japan earthquake and its surrounding regions. Then we present annual accumulated gravity changes, differential gravity changes and co-seismic gravity changes in the M_W9.0 source region and its surrounding regions. Meanwhile empirical orthogonal function method is applied to study the contribution of the earthquake to regional gravity changes. The results show that GRACE is able to reveal the evolution of regional gravity field accompanied with the M_W9.0 earthquake, the gravity changes reached about 2×10-8 m/s2 in the studied area three years before the M_W9.0 earthquake. Furthermore, the change in coseismic gravity and post-seismic regional gravity field are significant. The results from empirical orthogonal function method indicate that the coseismic effect with temporal and spatial gravity characteristics are presented in the first mode, which fully demonstrates that the Japan earthquake had significant influence on the regional gravity field.