南北地震带北段近年地壳水平运动  

Recent horizontal crustal movement in north segment of North-South seismic belt

作　　者：张楠[1] 许文俊[1] 王静[1] 王利波 李蒙亚 

机构地区：[1]宁夏回族自治区地震局,中国银川750001

出　　处：《地震地磁观测与研究》2018年第4期58-77,共20页Seismological and Geomagnetic Observation and Research

基　　金：基于GNSS分析南北地震带北段近期地壳运动特征与汶川等地震背景(课题号:163001);中国地震局2016年"地震监测预测科研三结合"课题

摘　　要：采用中国地震局陆态网络数据,解算并对比南北地震带北段速度场、速度投影、基线时间序列。对比发现:(1)各点速度矢量呈顺时针旋转;(2)相对于鄂尔多斯块体,2011—2015年银川地堑各站(银川、盐池、中卫、海原等)沿NNW方向扩张;(3)祁连断裂表现为左旋剪切和逆冲挤压,2013年起闭锁加强;海原断裂表现为稳定的左旋和逆冲,2013年起剪切加速;六盘山断裂表现为持续并放缓的逆冲和较弱的右旋;西秦岭北缘断裂带西段呈高速且放缓的逆冲以及高速但低应变累积的左旋,东段保持高速稳定的左旋和持续逆冲。By using GNSS observation datum of China Earthquake Administration ＂CMONOC＂, this study calculates and compares 7 sections of velocity fields of the north section of North-South seismic belt（32 °-43 °N, 95°-112°E） in ITRF2008 framework（relative to Eurasia）, it compares velocity projections to these faults on both sides within 50-350 km, and calculates time sequences of relative changes of arc lengths across the fractures or not. Results show that the velocity vectors at the northern section of North-South seismic belt in Eurasian framework display clockwise rotation of NNE-NENEE. The movement rate of the Yinchuan graben stations relative to the Ordos block increased year by year, and the movement accelerated along the NNW direction（except the southern part of the graben） from 2011. Since 1999, the Qilian fault showed significant sinistral shear and thrust extrusion, and from 2013 the thrust and shear stress maintained growth momentum with strengthened locking; Haiyuan fault showed stable stress accumulation of sinistral shear and thrust compression, from 2013 sinistral shear had an acceleration and thrust extrusion remained stable with reinforced locking; As of 2015, Liuanshan fracture performanced weak and continuous thrust extrusion and slow dextral stress accumulation, from 2013 thrust extrusion continued except between Lanzhou and Dingxi; As of 2015 western section of the northern margin of west Qinling Mountains fault zone have thrust extrusion with high speed but becoming slow, and low sinistral shear stress accumulation with high motion speed; From 2013 eastern section maintained sinistral shear stress accumulation with high rate and stability, and continuous locking thrust compressional stress accumulation.

关 键 词：南北地震带北段 GNSS 速度场 速度剖面 基线 

分 类 号：P315.2[天文地球—地震学]