基于区域水准和跨断层资料分析云南地区地壳形变

摘要

In order to obtain the present crustal deformation and fault activity characteristics in the Yunnan area, we collected the two periods precise leveling data in the Yunnan area since the 1990 s, used the adjustment method with GNSS station vertical deformation information constraint, and analyzed the characteristics of regional crustal deformation, the results show that the overall performance of northwest Yunnan regional crustal is characterized by uplift, with the vertical velocity of 2-3 mm/a. the southern region, however, is characterized by that the crustal subsidence rate of -1- -2 mm/a, and the existence of high gradient belt of crustal deformation in the Xiaguan-Yongsheng and Simao-Jinggu area; By collecting ross-fault observation data of more than thirty years, we calculated the 3-D of the fault, and obtained the present active state and abnormal characteristics of the fault, it is considered that the sites in Northwest and Central-South Region of Yunnan show collective abnormal activity.Among them, faults monitored by the Chuxiong, Jianchuan, Yongsheng site show strike slip and tensile features contrary to geologic background, and faults monitored by the Eshan, Jianshui, Tonghai sites is contrary to the geological background in compression and extension. Combined with the regional precise leveling and cross-fault observation results, it is considered that crustal deformation and fault activity anomalies exist in the northwest and central-south region of Yunnan, and tectonic stress accumulation is high. However, the background of current earthquake activity is relative low, attention should be paid on the short-term risk of moderate-strong earthquake in this area.%为了获取云南地区现今地壳形变和断层活动特征,收集了云南地区1992-2016年的2期精密水准观测资料,采用基于GNSS连续站垂直形变资料约束的平差方法,对区域整体地壳垂直形变特征进行了分析,结果显示滇西北区域地壳整体表现为隆升,垂向速率为2-3mm/a,滇南区域显示地壳沉降速率为-1--2mm/a,并在下关—永胜和思茅—景谷一带存在地壳形变高梯度带.收集了该地区30多年的跨断层场地观测资料,计算了所跨断层的三维活动量,得出了断层现今活动状态和异常特征,认为滇西北和滇中南地区的场地多数表现出异常活动的现象,其中楚雄、剑川和永胜的监测断层现今表现出与地质背景相反的走滑和拉张特征,峨山、建水和通海场地所处断层在张压性质上与地质背景相反.结合区域水准和跨断层观测分析结果,从"面"和"线"上得出滇西北和滇中南地区存在地壳形变和断层活动异常,构造应力积累较高的结果,加之缺震背景显著,认为应关注该区域中强地震的危险性.