摘要
河西走廊—祁连山北缘地区地处青藏高原北缘,受印度板块与欧亚板块中生代末—新生代早期的碰撞及持续至今的向北推挤作用的远程效应的影响,该地区是现今的地壳活动地区,其中地壳形变是最主要的表现形式。地壳形变监测显示,隆起区垂直位移速率最大可达15mm/a,沉降区最大位移速率为-15mm/a。祁连山和河西走廊的相对隆升变化与该区地震具有密切的关系,河西走廊相对下降、祁连山相对隆升的后期是地震多发时期,河西走廊相对隆升、祁连山相对下降的后期是地震少发时期,这与该区处于挤压体制下的区域构造背景密切相关。GPS水平位移监测显示,河西走廊—祁连山北缘地区全区都一致向东位移,且位移速率非常大,大者大于10mm/a;位移速率具有南部大于北部、东部大于西部的特点,水平位移速率变化与现代活动断裂具有非常密切的关系,并以主要断裂构造为区带的边界;水平位移速率矢量与2002年玉门地震的震源机制解所显示的沿地震破裂面发生的滑动方向非常一致。
Northern Qilianshan margin-Hexi Corridor area is situated in the northern margin of Qinghai-Xizang Plteau. Because of the collision of the Indian plate and the Eurasian plate from late Mesozoic to early Cenozoic and their long-distance effect of the con- tinuous compression up to now, northern Qilianshan margin-Hexi Corridor area is a strong present crustal movement zone, and geodetic deformation is one of the main forms of the movement. The geodetic deformation monitoring shows the largest vertical deformation rate is ＋15mm/a in upwelling area and -15mm/a in subsidence area. The relative changes of the upwelling and subsidence between the Qilianshan and Hexi Corridor are related to the earthquakes in the area. When the Hexi Corridor area is subsiding and Qilianshan area is upwelling, there are many earthquake activities, while the Hexi corridor area is upwelling and Qilianshan area is subsiding, there are few earthquake activities. That is a result from the tectonic setting of compression stress field. The GPS horizontal crustal displacement monitoring shows that the horizontal crustal displacement is toward the East and the displacement rate is rapid （the fastest rate is more than 10mm/a）. And the horizontal deformation rate changes more in the southern part than in the northern part, more in the eastern part than in the western part. The changes of the horizontal deformation rate are related to the active faults and the different rate zone divided by the main active fault as boundary. Vector of the horizontal crustal displacement is identical to the glide direction along the seismic fracture shown by mechanism interpretation of the quake-source on 2002, Yumen earthquake.
出处
《地质通报》
CAS
CSCD
北大核心
2009年第10期1439-1447,共9页
Geological Bulletin of China
基金
中国地质调查局地质调查项目(编号:水[2003]018-02和水[2005]018-04)资助
关键词
地震活动
大地形变
垂直位移
水平位移
祁连山北缘—河西走廊地区
earthquake activity geodetic deformation vertical displacement horizontal displacement northern Qilianshan margin- Hexi Corridor area
