珠峰及周边地区强震影响垂直形变特征研究

2015年尼泊尔地震对珠穆朗玛峰高程的影响,近年一直受到全世界关注。2020年珠穆朗玛峰高程测量在珠穆朗玛峰及周边地区布设了高精度的全球导航卫星系统(global navigation satellite system, GNSS)形变监测网,收集了1999—2020年跨喜马拉雅山脉的32个连续运行参考站(continuously operating reference stations, CORS)的GNSS连续观测数据。利用GNSS数据监测了珠穆朗玛峰周边地区地壳三维形变特征,定量获取了2015年尼泊尔强震对珠穆朗玛峰周边CORS同震位移,以及地震对区域地壳三维形变长期趋势的影响,特别是对该地区垂直形变的影响。研究结果表明,该区域地壳垂直形变由南至北跨喜马拉雅山脉呈明显的阶梯型分布特征;震后印度板块与欧亚板块存在加速汇聚趋势,导致震后地壳隆升速率同步增大。

Vertical Deformation Characteristics Affected by Strong Earthquakes in Mount Qomolangma and Surrounding Areas

  Objectives  The impact of the 2015 Nepal earthquake on the height of Mount Qomolangma has attracted worldwide attention in recent years. 2020 height measurement of Mount Qomolangma has set up a high-precision GNSS(global navigation satellite system) deformation monitoring network in Mount Qomolangma and its surrounding areas. In addition, we have collected the GNSS observation datum of 32 CORS(continuously operating reference stations) across the Himalayas during 1999 to 2020.  Methods  We monitor the three-dimensional crustal deformation characteristics of Mount Qomolangma and surrounding areas, and quantitatively obtained the co-seismic displacement of the CORS around the Mount Qomolangma of the 2015 Nepal earthquake, as well as the impact of the earthquake on the long-term trend of regional three-dimensional crustal deformation, especially on the vertical deformation in this region.  Results  The results show that the vertical crustal deformation in this area has obvious stepped distribution characteristics from south to north across the Himalayas. After the earthquake, there was an accelerated convergence trend between the Indian plate and the Eurasian plate, which led to the synchronous increase of the crustal uplift rate after the earthquake.  Conclusions  The crustal rise in Mount Qomolangma and surrounding areas is the main trend. The 2015 Nepal earthquake caused the crustal decline in a short time, but did not change the long-term uplift trend.