2011年新疆伽师M_S5.8地震重力场前兆异常特征
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摘要
利用2011年8月11日新疆伽师MS5.8地震前喀什—伽师流动重力网2009年4月至2011年7月的重力复测数据,绘制区域重力场差分和累计动态变化图像。分析表明:(1)地震发生在断裂带重力变化正、负异常密集区的零等值线附近和重力场的反向恢复变化过程中;地震发生前一年出现"闭锁"的重力变化特征;(2)区域重力场差分变化反映出震前伽师—西克尔地区地壳物质运动信息;区域重力场的"平静—活跃"过程,反映出伽师—西克尔区域重力场短期局部构造运动;区域重力场累计动态变化反映出地壳运动的背景特征;(3)地震震前重力变化等值线平行于断层分布,临震时重力变化等值线近垂直于断层,是一个显著的重力特征。
Using the gravimetric data of the second measuring from Apr.,2009 to Jul.,2011 in Kashi-Jiashi mobile gravity network before Jiashi MS5.8 earthquake on Aug.11,2011,we obtained dynamic differential and cumulative change maps of regional gravity field.The results show as follows:(1) The earthquakes occurred near the "0"contour line in the concentrated region of gravity positive and negative anomalies of the fault zone and in the reverse recovery process of the gravity field.(2) Difference changes of regional gravity field reflected crustal substance movement in JiaShi-Xiker area before Jiashi MS5.8 Earthquake."Peace-active"process of regional gravity field reflected the local tectonic movement in short time.The accumulated dynamic change of region gravity field reflected the background characteristics of crustal movement.(3) The contour line of gravity variation paralleled to the fault before earthquake,however it perpendiculared to the fault before the shock,which was an significant gravity characteristics.
Using the gravimetric data of the second measuring from Apr.,2009 to Jul.,2011 in Kashi-Jiashi mobile gravity network before Jiashi MS5.8 earthquake on Aug.11,2011,we obtained dynamic differential and cumulative change maps of regional gravity field.The results show as follows:(1) The earthquakes occurred near the "0"contour line in the concentrated region of gravity positive and negative anomalies of the fault zone and in the reverse recovery process of the gravity field.(2) Difference changes of regional gravity field reflected crustal substance movement in JiaShi-Xiker area before Jiashi MS5.8 Earthquake."Peace-active"process of regional gravity field reflected the local tectonic movement in short time.The accumulated dynamic change of region gravity field reflected the background characteristics of crustal movement.(3) The contour line of gravity variation paralleled to the fault before earthquake,however it perpendiculared to the fault before the shock,which was an significant gravity characteristics.
引文
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屠泓为,万秀红,高歌,等.2008.1977年至2006年新疆伽师地震断层性质及应力场变化原因初探[J].地球物理学进展,23(4):1038-1044.
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王晓强,王琪,程瑞忠,等.2002.新疆伽师及临近地区现今地壳形变的GPS监测研究[J].西北地震学报,24(3):20-24.
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