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基于GRACE卫星时变重力数据,利用小波多尺度分解方法,分析研究了芦山MS7.0地震前重力场的时空动态演化特征.结果表明,雅安地区震前卫星时变重力场具有明显的重力变化信息.卫星时变重力场在时间域表现为,累积重力场和差分重力场存在较强的规律性动态变化,以2003—2004年均值为基值的2009—2012年的变化特征与2005—2007年的变化特征具有较好的相似性,以2009年均值为基值的2009—2012年即芦山地震前4年,芦山震区的时变重力场呈现上升→减速上升→加速上升以及上升→轻微下降→快速上升的变化特征;卫星重力场在空间域表现为,震中位置由靠近重力场正变化的中心→接近重力场正变化边缘→接近重力正变化四象限分布中心的变化特征.因此,芦山地震的重力场动态变化信息和波场分离结果符合逆冲推覆兼走滑型地震引起的区域变形特征.
Based on the time-varying gravimetric data of GRACE satellite, the temporal and spatial dynamic evolution characteristics of gravitational field before the MS 7.0 Lushan earthquake are studied by means of wavelet multi-scale decomposition. The results show that the time-space dynamic gravitational field of the satellite before the earthquake in Ya’an has obvious gravity change information The temporal variation of satellite gravity field in the time domain shows that the cumulative gravity field and the differential gravitational field have strong regular dynamic changes. The changes from 2009 to 2012 based on the mean value from 2003 to 2004 are similar to those from 2005 to 2007 The change characteristics of the Lushan earthquake area in 2009-2012, ie, the year 2009-2012 before the Lushan Earthquake in 2009, showed a good similarity. The time-varying gravitational field in Lushan earthquake area showed a rise → a deceleration increase → an acceleration increase and a slight decrease → rapidly rising change characteristics. The satellite gravity field shows in the spatial domain that the epicenter position is near the center of the positive change in gravity field → close to the positive edge of the gravitational field → close to the four-quadrant distribution center of gravity positive change. Therefore, the Lushan earthquake The dynamic changes of gravity field and the results of wavefield separation are in accordance with the regional deformation characteristics caused by thrust nappe and strike-slip earthquakes.