昆仑山8.1级地震前中国大陆的构造应变背景

利用“网络工程”1998～2001年累积的1181个测站的GPS重复观测资料，采用双三次样条函数模型建立中国大陆水平运动模型速度场，用大地坐标在椭球面上计算各类应变场，详细分析了2001年昆仑山8．1级地震前中国大陆水平构造应变场空间分布特征。各类构造应变场的最高值都出现在喜马拉雅构造带与昆仑山地块内(地震断裂带南侧)，鲜水河—安宁河断裂带次之。分析表明，昆仑山8．1级地震正好发生在张性面膨胀应变率的高值区，第一、第二和最大剪应变率高值区边缘的突变区和最大、最小主应变率的高值区。

TECTONIC STRAIN BACKGROUND IN CHINA CONTINENT BEFORE KUNLUN MOUNTAIN Ms8.1 EARTHQUAKE

Assuming that the contemporary tectonic activity in China can be considered as continuous. We have simulated 1 181 velocity solution within or around China with a bi-cubic spline interpolation function to inverse the integer horizontal velocity, to estimate strain rate fields with geodetic coordinates on ellipsoid of China, which come from the multiple-epoch Global Position System observation data of Crustal Movement Observation Network of China (CMONOC) from 1998 to 2001. The characteristic analysis about spatial distribution of horizontal strain rate fields shows the tectonic deformation background of the Kunlun mountain\{\%M\%s8.1\} earthquake. The maximum of strain rate exists in the Himalaya tectonic zone and Kunlun mountain block. The strain rate images show that the \%M\%s8.1 earthquake occurred in the high value zones of extension surface dilatation strain rate and in the abrupt zone of the margins of first and second shear strain rate and the high value zone of the maximum and minimium principal strain rate.