川滇地区近期地壳变形动态特征研究

The Deformation Characteristics of Sichuan-Yunnan Region in Recent Period

基于1999年以来的GPS观测数据,重点分析了川滇地区近期的变形特征,计算给出了该区域主要断裂带的滑动速率,并结合GPS剖面初步识别了断裂带所处的孕震阶段。结果表明,红河断裂带始终处于弱形变区域,值得进一步关注;汶川地震后,由于研究区域应力场的调整和应变的重新分配,使得安宁河断裂带的活动变化较小,逐步趋缓,走滑分量存在明显趋缓现象,并且安宁河断裂带的闭锁深度在一定程度上有所增加;小江断裂带的走滑分量存在明显趋缓现象,显示存在强闭锁现象,小江断裂带平行于断层方向GPS速度剖面显示断裂带两侧变形平缓且变形范围较大;昭通、莲峰断裂的挤压和剪切变形积累均存在弱化现象,可能预示该区域挤压应变积累背景较高。

Based on the GPS observation data since 1999,recent deformation characteristics of Sichuan-yunnan region is analyzed,slip rates of main faults are calculated,meanwhile,GPS profiles are combined to analyze the periods of the earthquake generating.The results show that,East edge of Sichuan-Yunnan block：Xianshuihe fault,Anninghe fault,Zemuhe fault,Xiaojiang fault have intense activity,and the movement of the faults are given priority to left-lateral strike-slip.Honghe fault is still in the weak deformation area and the middle section of the Honghe fault zone is the maximum shear strain rate region,while the shear deformation in the northwest and southeast segment of the Honghe fault is higher,which deserves further attention.After Wenchuan earthquake,due to the adjustment of regional stress field and strain redistribution,the activity of the Anning river fault zone is relatively small,easing gradually,and the sliding component has the obvious tendency of slowing down,and the blocking depth of the Anning river fault zone has increased to a certain extent.With the south of the material,the speed of the south segment of the Xiaojiang fault is slowed down and the locking depth increases.GPS velocity profile in parallel to the fault direction of the Xiaojiang fault line shows that the deformation of the fault zone is smooth and the deformation scale is large,showing that there are strong blocking phenomenon.After the Ludian earthquake,the strain release of Zhaotong and Lianfeng fault zone was not significant,compression strain and shear deformation accumulation of Zhaotong-lianfeng is weakening,may indicate that the compressive strain accumulating background is higher.