昆仑山口西8.1级地震前重力变化
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摘要
利用青藏地区 1998～ 2 0 0 0年绝对重力和相对重力观测资料获得的区域重力场空间动态变化结果 ,初步分析了该区重力变化特征及其与监测区内 8.1级大地震的关系 .结果表明 :①昆仑山口西 8.1级大地震发生在重力负值变化高值区附近的重力变化高梯度带上 ;② 8.1级大地震前的主要构造变形与能量积累在震中的南侧 ;③主震震中以东重力负值变化高值区的范围与野外地质考察结果的破裂区域吻合得较好 ;④重力负值变化高值区的分布与GPS观测给出的应变场第二剪应变高值区一致 .
The relation between the gravity variation features and M _S8.1 earthquake in Qinghai-Tibet monitoring area is analyzed preliminarily, by using spatial dynamic variation results of regional gravity field from absolute gravity and relative gravity observation in 1998 and 2000. The results show that: ① M _S8.1 earthquake in Kunlun mountain pass western occurred in the gravity variation high gradient near gravity′s high negative variation; ② The main tectonic deformation and energy accumulation before M _S8.1 earthquake are distributed at south side of the epicenter;③ The range of gravity′s high negative variation at east of the M _S8.1 earthquake epicenter relatively coincides with that rupture region according to field geology investigation; ④ Gravity variation distribution in high negative value region is just consistent with the second shear strain′s high value region of strain field obtained from GPS observation.
The relation between the gravity variation features and M _S8.1 earthquake in Qinghai-Tibet monitoring area is analyzed preliminarily, by using spatial dynamic variation results of regional gravity field from absolute gravity and relative gravity observation in 1998 and 2000. The results show that: ① M _S8.1 earthquake in Kunlun mountain pass western occurred in the gravity variation high gradient near gravity′s high negative variation; ② The main tectonic deformation and energy accumulation before M _S8.1 earthquake are distributed at south side of the epicenter;③ The range of gravity′s high negative variation at east of the M _S8.1 earthquake epicenter relatively coincides with that rupture region according to field geology investigation; ④ Gravity variation distribution in high negative value region is just consistent with the second shear strain′s high value region of strain field obtained from GPS observation.
引文
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青海省地震局,中国地震局地壳应力研究所.1999.东昆仑活动断裂带[M].北京:地震出版社,18～27
徐锡伟,陈文彬,于贵华,等.2002.2001年11月14日昆仑山库赛湖地震(MS8.1)地表破裂带的基本特征[J].地震地质,24(1):1～13
张为民,王勇,詹金刚.2001.中国地壳运动观测网络基准站绝对重力的测定[J].地壳形变与地震,21(4):114～116
祝意青,胡斌,张永志.1999.永登5.8级地震前后的重力场动态图像特征研究[J].地壳形变与地震,19(1):71～77
祝意青,江在森,程宏宾.2001.西北GPS网络重力场变化与地震活动分析[J].内陆地震,15(3):211～217
①中国地震局分析预报中心.2001年11月14日昆仑山口西8.1级大地震简介.震情研究,(4):79～101.
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