云南地区及邻域卫星重力变化及其与区域大震的关系

Satellite Gravity Changes in Yunnan and Adjacent Regions and Its Relation with Regional Strong Earthquakes

利用GRACE卫星重力场数据,计算并分析云南地区及邻域2003—2014年的卫星重力场变化特征,获得3个特征点上的月重力变化时间序列;结合该地区2003—2014年发生的M_S5以上地震分布,探讨区域卫星重力变化与区域大震的关系。结果表明:云南地区及邻域卫星重力场变化对区域M_S5以上地震有一定的反映,地震多发生在区域重力变化的高梯度带上,地震发生前后,区域出现与地震相对应的特征性卫星重力变化,可能是对壳幔物质调整的反映;区域大震前后,不同震区特征点的重力变化特征存在差异,说明分断层、分区域的重力场变化研究对地震预测有重大意义。

Yunnan is one of the main seismic activity areas in China.It lies close to the subduction zone where the Indian plate moves towards the Eurasian plate and belongs to the southern section of the north-south seismic belt in China.Historical earthquake activity in this area shows that earthquakes of high frequency and large magnitude occur.The Yunnan region and its adj acent are-as are ideal locations for the study of seismicity.Existing research shows that regional seismic ac-tivity is closely related to gravity field changes that are mainly caused by geological activities such as crustal deformation and fault material change.Such changes reflect crustal movement and the associated processes involved in large earthquakes.Therefore,gravity changes can be used to pre-dict earthquakes.The GRACE （Gravity Recovery and Climate Experiment）binary star system, jointly developed by NASA and the DLR,provides a time-varying gravity field and thus important information for the exploration of Earth＇s interior materials.GRACE satellite observations clearly reflect the motion of the Earth＇s plates and expand the scope of gravity anomaly seismic observa-tions that can be used for long-term forecasts of earthquakes.In this paper,we use gravity field data from GRACE satellites to calculate and analyze the satellite gravity field variation character-istics from 2003 to 2014 in the Yunnan region and its adjacent areas.We also obtained the monthly gravity change sequence of three feature points,and in this study we analyze their change charac-teristics by combining the distribution of M≥5 earthquakes from 2003 to 2014 in the study area. Results show that the MS≥5 earthquakes in the Yunnan region and adj acent areas are reflected in satellite images of gravity field changes,and that large earthquakes often occur on the high gradi-ent zone of regional gravity changes.The earthquake zone often shows a corresponding change in satellite gravity characteristics both before and after large earthquakes,which may reflect crust-mantle material adj ustment.The corresponding earthquake gravity change characteristics of the three points are different,which may indicate that research into the gravity field changes in vari-ous regions and faults is significant for earthquake prediction.