We collect,sort,process and analyze velocity field data,obtained before and after April 25,2015 MsS.1 Nepal earthquake,from the earthquake zone and the Qinghai-Tibet plateau areas of China.According to the pre-seismic velocity field,the Himalayan tectonic belt presents compression characteristics of about 16 mm/a.Furthermore,according to the deformation characteristics,the pre-seismic Himalayan tectonic belt can be divided into eastern,central and western sections.The earthquake occurred in the middle and the main squeeze is northerly.The eastern and western sections have clockwise and counterclockwise characteristics,respectively.After the earthquake,the velocity field shows that the tectonic deformation of the impact is greater in Nepal and Southern Tibet,mainly because the pushing speed of the Himalayan tectonic belt decreases,the Southern Tibet north south movement decreases,and the east-west speed increases.This phenomenon may have great impact on strike-slip faults in the Southern Tibet area.%通过对尼泊尔Ms8.1地震前后附近区域GPS台站记录到的观测数据进行处理,获得了震区以及中国青藏高原地区地震前后GPS站点速度场以及震后形变场.震前速度场显示,喜马拉雅构造带整体呈现出约16 mm/a的压缩特征.同时,震前喜马拉雅构造带根据形变特征可分为东、中、西3段,其地震发生在中段,主要以北向挤压为主,而东西两段分别具有逆时针旋转和顺时针旋转的特征.震后GPS站点形变场显示,此次地震对中国新疆、青海、西藏等地区的影响较大,其最大震后位移达20 mm左右.震后速度场显示,本次地震对尼泊尔地区以及中国藏南地区的构造形变影响较大,主要表现为喜马拉雅构造带的年推挤速度减小,藏南地区的南北向运动速率减小,而东西向速度有增大的现象.这一现象可能对藏南地区的走滑断层有较大影响.
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