Deformation measurements such as short range leveling, short baseline, continuous cross fault strain measurement are carried out at different intervals from 1982 to 2001.All these measurement sites are built across th...Deformation measurements such as short range leveling, short baseline, continuous cross fault strain measurement are carried out at different intervals from 1982 to 2001.All these measurement sites are built across the boundary tectonic belts of Yunnan Sichuan block. On the basis of these deformation data, the annual deformation rates at all sites are calculated and their change curves with time are plotted respectively. With these calculated results, we analyze the vertical and horizontal movements of tectonic belts of Yunnan Sichuan block, and the relationship to grouped strong earthquakes occurred in the block are discussed as well. These results show that the tectonic activities in the western and southeastern Yunnan are intensive. Along some eastern boundary belts: from Qujiang, Xiaojiang fault belts in the south of Yunnan to Xianshuihe fault belts in northwestern Sichuan, present annual rate of horizontal deformation decreases.Along Xianshuihe, Xiaojiang and Longmenshan fault belts the rates of vertical deformation change are small,but the vertical deformation change rates along Anninghe and Zemuhe fault belts are comparatively large. The comprehensive analysis shows that grouped strong earthquakes will occur probably when the deformation rate changes sharply. Thus we think that sharp changes of deformation rates may be one of the seismic precursors.展开更多
文摘Deformation measurements such as short range leveling, short baseline, continuous cross fault strain measurement are carried out at different intervals from 1982 to 2001.All these measurement sites are built across the boundary tectonic belts of Yunnan Sichuan block. On the basis of these deformation data, the annual deformation rates at all sites are calculated and their change curves with time are plotted respectively. With these calculated results, we analyze the vertical and horizontal movements of tectonic belts of Yunnan Sichuan block, and the relationship to grouped strong earthquakes occurred in the block are discussed as well. These results show that the tectonic activities in the western and southeastern Yunnan are intensive. Along some eastern boundary belts: from Qujiang, Xiaojiang fault belts in the south of Yunnan to Xianshuihe fault belts in northwestern Sichuan, present annual rate of horizontal deformation decreases.Along Xianshuihe, Xiaojiang and Longmenshan fault belts the rates of vertical deformation change are small,but the vertical deformation change rates along Anninghe and Zemuhe fault belts are comparatively large. The comprehensive analysis shows that grouped strong earthquakes will occur probably when the deformation rate changes sharply. Thus we think that sharp changes of deformation rates may be one of the seismic precursors.
