利用GRACE数据检测日本Mw9.0地震同震和震后重力变化

基于德国地学中心（GFZ）发布的GRACE RL05月重力场模型数据，考虑全球陆地同化系统陆地水储量的影响，采用300 km的扇形滤波，利用叠积法提取了日本Mw9.0地震的同震和震后重力时变信号，并利用最小二乘拟合的方法计算了两个同震重力变化极值点在地震前后85个月的重力年变率。结果表明：土壤水分和雪水引起的重力变化为-0.34~0.09 μgal；利用GRACE数据检测到的同震重力变化为-5.3~4.2 μgal，与基于PSGRN/PSCMP模型计算的结果在空间分布和量级上具有较好的一致性；震后5 a震中附近区域的重力整体上呈现增加趋势，断层上盘所在的日本海域与下盘所在的太平洋区域重力增加的最大值分别为2.6、4.5 μgal，下盘重力增加较大，可能与断层下盘所在地层的黏滞性相对较低有关。

Co-seismic and Post-seismic Gravity Changes of the Japan Mw9.0 Earthquake from GRACE RL05 Data

Based on the RL05 earth gravity field model released by GFZ,considering the influence of the terrestrial water reserves in the global land data assimilation system,the co-seismic and post-seismic gravity changes caused by the 2011 Japan Mw9.0 earthquake is successfully extracted by using the method of stacking and 300 km fan filter.The gravity annual variation rate of the two characteristic points around the epicenter is calculated as well by using the method of least squares fitting in 85 months before and after the earthquake.The results show that the gravity change caused by the soil moisture content and accum snow is -0.34～0.09μgal;the co-seismic gravity changes from the GRACE RL05 data is -5.3～4.2μgal,which is consistent well with the result based on the PSGRN /PSCMP model in spatial distribution and order of magnitude;the gravity increasing trend is showed in the area around the epicenter in 5 years after the earthquake,the maximum increase in gravity of the Sea of Japan the upper plate locates and the Pacific Ocean the subduction area locates is 2.6μgal and 4.5μgal,respectively,the gravity of the subduction area increases greater,indicating that the viscosity of the subduction area is relatively lower than that of the up-lift zone.