汶川地震前后的重力异常变化特征分析
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摘要
地震在地壳深处孕育发展,造成地壳内部应力和应变的变换以及物质密度变化,从而在地表造成重力变化,卫星重力探测技术可以实时或连续的监测这种变化。文中利用GRACE卫星数据计算汶川地区2008年间各月份的重力异常值,结合汶川地区所处地质构造,对5·12汶川地震前后重力异常变化特征进行分析。结果表明,汶川地震前该地区重力异常有9.31E-08m/s2的上升变化,而在2008年整体变化上则处于下降趋势,说明其1—11月间处于应力累积阶段。分析表明,卫星重力测量技术应用于地震前兆研究有其可行性。
Crustal stress and strain transforms and density changes when the earthquake develops in the deep crust,which results in the changes of surface gravity that can be monitored by satellite gravity technology in real time or constantly.GRACE satellite data is used to calculate the gravity anomaly values of the Wenchuan area every month in 2008,and the gravity anomaly characteristics before and after the 5/12 Wenchuan earthquake are analyzed with the geological structure of the Wenchuan area.Conclusions show that the gravity anomaly in this area is increased by 9.31 E-08 m/s2 before Wenchuan earthquake,while the overall change is in the downward trend,which means that this area was in stress accumulation stage between January and November in 2008.This analysis shows that it is feasible to apply satellite gravimetry to the earthquake precursor study.
Crustal stress and strain transforms and density changes when the earthquake develops in the deep crust,which results in the changes of surface gravity that can be monitored by satellite gravity technology in real time or constantly.GRACE satellite data is used to calculate the gravity anomaly values of the Wenchuan area every month in 2008,and the gravity anomaly characteristics before and after the 5/12 Wenchuan earthquake are analyzed with the geological structure of the Wenchuan area.Conclusions show that the gravity anomaly in this area is increased by 9.31 E-08 m/s2 before Wenchuan earthquake,while the overall change is in the downward trend,which means that this area was in stress accumulation stage between January and November in 2008.This analysis shows that it is feasible to apply satellite gravimetry to the earthquake precursor study.
引文
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[2]郑伟,许厚泽,钟敏,等.地球重力场模型研究进展和现状[J].大地测量与地球动力学,2010,30(4):82-91.
[3]李渭娟.震前重力异常的讨论[J].西北地震学报,1979,1(2):77-80.
[4]段虎荣,张永志,刘锋,等.利用GRACE卫星数据研究汶川地震前后重力场的变化[J].地震研究,2009,32(3):295-298.
[5]吴星,刘雁雨.多种超高阶次缔合勒让德函数计算方法的比较[J].测绘科学技术学报,2006,23(3):188-191.
[6]罗志才.利用卫星重力梯度数据确定地球重力场的理论和方法[D].武汉:武汉测绘科技大学,1996.
[7]罗志才,吴云龙,钟波,等.GOCE卫星重力梯度测量数据的预处理[J].武汉大学学报(信息科学版),2009,34(10):1163-1167.
[8]李飞.利用GRACE数据研究大地水准面和重力异常[D].西安:长安大学,2008.
[9]邢乐林,李辉,周新,等.GRACE卫星重力观测在强震监测中的应用及分析[J].大地测量与地球动力学,2010,30(4):51-58.
[10]吴国华,罗增雄,赖群.丽江7.0级地震前后滇西实验场的重力异常变化特征[J].地震研究,1997,20(1):101-107.
[11]张明华,张家强.现代卫星测高重力异常分辨能力分析及在海洋资源调查中应用[J].物探与化探,2005,29(4):295-303.
[12]吴云成,李子涛.辽宁西部地区地震前后重力异常反映[J].东北地震研究,1997,13(2):13-19.
[13]华昌才,郑金涵,刘端法.大同-阳高地震重力异常[J].地震学报,1992,14(3):369-372.
[14]黄健,詹景立,李爱霞.雅江6.0级地震前后的重力变化异常特征[J].四川地震,2004(11):27-30.
[15]翟振和.卫星重力测量的主要方法和发展现状[J].测绘科学与工程,2004,24(3):50-55.
[16]刘栋勋,刘文泰.大震及中强震前重力变化实例[J].四川地震,1986(2):13-18.