中文摘要：

利用多年GRACE卫星重力变化资料,给出尼泊尔及周缘地区的重力场时空变化,以探索2015-04-25尼泊尔M8.1地震震前重力变化特征;并基于球形位错理论,利用断层模型数据模拟同震重力场变化。研究表明,区域重力场变化以2008年为界存在明显的分时段特征,2003--2008年以重力增加为主,而2009--2014年以重力减少为主;且存在明显的分区性,区域重力场在尼泊尔地震震中四周呈正负相间分布;震前局部重力场变化在压缩区重力增加,拉张区重力减少,与理论同震重力变化结果一致。总结研究区域近年来M7.0以上地震震前重力变化特征发现,地震基本发生在重力变化高梯度带的过渡带及重力变化零值线附近。

英文摘要：

This paper presents temporal and spatial variations of the gravity field in Nepal and its pe- riphery. It further explores the regional long-term gravity changes prior to the April 25 2015, M8.1 Nepal earthquake by using GRACE satellite gravity data. Co-seismic geoid and. gravity changes based on spherical dislocation theory are simulated with the fault model. The results show obvious charac- teristics of regional gravity field features in different periods, i. e. , gravity increases during 2003-2008 and decreases during 2009--2014. Meanwhile the regional gravity field around the epicenter is in the center of positive and negative changes. Compared with theoretical gravity variation, the GRACE re- gional gravity field shows similar results, gravity increases in the compression zone and reduces in the tension area. This research reveals that earthquakes occur in the transition zone of gravity gradient changes and around zero line of gravity variations. GRACE gravity variations before an earthquake provide an important basis to explore the earthquake focal mechanism and earthquake predictions.