Preliminary Analysis of the Sichuan-Yunnan Block and Surrounding Fault Movement Using GNSS Continuous Observation Data
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摘要: 本文利用GNSS连续站的资料分析2016、2017年川滇块体和巴彦喀拉块体速度场、应变场特征,认为道孚、西昌和马尔康附近应力积累相对集中。分析GNSS连续站点的相对速度发现,川滇块体内GNSS连续站的运动状态呈明显的顺时针旋转,巴彦喀拉块体也有顺时针旋转态势。此外,利用块体相对运动求解鲜水河断裂运动速率,鲜水河断裂西部的运动速率比东部稍大,约有2—3mm/a的差异。相比2016年,2017年鲜水河断裂运动速率变小,有利于缓解鲜水河断裂应变能的积累。Abstract: In this study, the GNSS continuous station data were analyzed to study the characteristics of the velocity field and strain field of the Sichuan-Yunnan block and the Bayan Har block in 2016-2017, in consideration of that the stress accumulation is relatively concentrated near Dawu, Xichang and Barkam. By analyzing the relative speed of GNSS continuous stations, we found that GNSS continuous station motion in both the Sichuan-Yunnan block and the Bayan Har blocks shows clockwise rotation. By using block relative motion to solve the speed of Xianshuihe fault, we found that the speed of the west of the Xianshuihe fault is slightly faster than that of the east, about 2 to 3 mm/a difference. The movement rate of the Xianshuihe fault in 2017 is smaller than that of 2016, that helps to alleviate the accumulation of strain energy in the Xianshuihe fault. The greater the fault slip difference between the model simulation and the actual measurement, the greater the energy that can be accumulated at the fault. As a result, the seismic energy concentration in the fracture energy concentration area is relatively greater.
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Key words:
- GNSS continuous station /
- Motion rate /
- Strain /
- Xianshuihe fault
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表 1 鲜水河断裂不同点位东向和北向运动速率
Table 1. The eastward and northward movement rate of different points on the Xianshuihe fault
年份 点位1(31.50°N,100.50°E)运动速率/mm·a-1 点位2(31.15°N,101.00°E)运动速率/mm·a-1 点位3(30.55°N,101.50°E)运动速率/mm·a-1 点位4(29.90°N,102.00°E)运动速率/mm·a-1 东向 北向 东向 北向 东向 北向 东向 北向 2016 8.2593 -13.499 7.8359 -12.7154 6.8531 -12.0765 5.7652 -11.4543 2017 7.7108 -12.5397 7.2934 -11.8507 6.2555 -11.5369 5.1012 -11.284 备注:东向速率表示为东向为正,西向为负;北向速率表示为北向为正,南向为负。 表 2 鲜水河断裂不同点位走滑和张压运动速率
Table 2. The strike slip and tension movement rate of different points on the Xianshuihe fault
年份 点位1(31.50°N,100.50°E)运动速率/mm·a-1 点位2(31.15°N,101.00°E)运动速率/mm·a-1 点位3(30.55°N,101.50°E)运动速率/mm·a-1 点位4(29.90°N,102.00°E)运动速率/mm·a-1 走滑 张压 走滑 张压 走滑 张压 走滑 张压 2016 13.9023 -7.5608 14.5320 -3.4503 13.3853 -3.6935 12.1760 -4.0228 2017 12.9476 -7.0043 13.5370 -3.2225 12.5811 -3.7345 11.5861 -4.3719 注:走滑速率表示为左旋为正,右旋为负;张压速率表示为张性为正,压性为负。 -
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