基于GPS和水准资料的拉脊山断裂带西段地壳形变研究

利用拉脊山地区1983~1995年水准资料，结合1999~2007年、2009~2014年GPS数据对拉脊山断裂带西段进行三维地壳形变分析。拉脊山断裂带西段垂直运动速率约为1±0.5 mm/a，表明该段处于隆升状态；与GPS数据显示出的水平挤压一致，拉脊山地区仍处于地壳水平挤压缩短状态，2008年之后断层两侧差异运动更加明显，地壳缩短速率增加并表现出明显的左旋走滑分量，与卫星影像解译和野外地质地貌调查结果一致。拉脊山断裂西段受挤压环境控制下的构造变形现今仍在持续进行，同时受全新世活动的日月山断裂右旋挤压应力影响。该地段是地震孕育的敏感部位，应该引起关注。

The Study of Crustal Deformation on Western End of Lajishan Fault Based on GPS and Leveling Data

The Lajishan area is an earthquake tectonic window to reflect on tectonic activity and earthquake activity. The Lajishan fault has caused about 20 moderate earthquakes on the both sides of Lajishan mountain in documented history. Lajishan fault is still an active fault zone, and has structural conditions of medium-strong earthquakes in the region. The Lajishan area is at 3 500 m above sea level and is not convenient for study. It remains doubtful whether the Lajishan regional crustal deformation is still in the uplift state. This paper uses 1983-1995 leveling data, combined with 1999-2007 and 2009-2014 GPS data, to analyze the three dimensional crustal deformation of this area. Research shows that the west section of Lajishan fault has a vertical rate of 1±0.5 mm/a ,which proves that the area is still in the uplift state. GPS data also show horizontal compression in this area. The Lajishan area remains a crustal horizontal shortening deformation. The crustal shortening rate of the region has become smaller, and shows an obvious left-lateral strike-slip component after 2008. The results are corroborated by satellite imagery interpretation and field geological survey results. Under the control of extrusion environment, tectonic deformation in the area is still ongoing. This area is also influenced by the Riyueshan right-lateral strike-slip fault. We should be concerned and put attention to seismic risk at the western end of Lajishan fault.