Lijiang-Daju fault, the seismogenic fault of the 1996 Lijiang M=7.0 earthquake, can be divided into Lijiang-Yuhu segment in the south and Yuhu-Daju segment in the north. The two segments show clear difference in geolo...Lijiang-Daju fault, the seismogenic fault of the 1996 Lijiang M=7.0 earthquake, can be divided into Lijiang-Yuhu segment in the south and Yuhu-Daju segment in the north. The two segments show clear difference in geological tectonics, but have the similar dynamic features. Both normal dip-slip and sinistral strike-slip coexist on the fault plane. This kind of movement started at the beginning of the Quaternary (2.4~2.5 Ma B.P.). As to the tectonic types, the detachment fault with low angle was developed in the Early Pleistocene and the normal fault with high angle only after the Mid-Pleistocene (0.8 Ma B.P.). Based on the horizontal displacements of gullies and the vertical variance of planation surfaces cross the Lijiang-Daju fault at east piedmont of Yulong-Haba range, the average horizontal and vertical slip rates are calculated. They are 0.84 mm/a and 0.70 mm/a since the Quaternary and 1.56 mm/a and 1.69 mm/a since the Mid-Pleistocene. The movements of the nearly N-S-trending Lijiang-Daju fault are controlled not only by the regional stress field, but also by the variant movement between the Yulong-Haba range and Lijiang basin. The two kinds of dynamic processes form the characteristics of seismotectonic environment of occurring the 1996 Lijiang earthquake.展开更多
By using the integral dynamic adjustment of the "segmentation rate," this paper processes the leveling repetition measurement data of the Dianxi(western Yunnan)area since the 1980s,makes the fitting of the v...By using the integral dynamic adjustment of the "segmentation rate," this paper processes the leveling repetition measurement data of the Dianxi(western Yunnan)area since the 1980s,makes the fitting of the velocity surface for vertical deformation with multi-surface function,and splits information of the vertical deformation field.The dynamic evolution of the deformation field and vertical deformation information norm-shear deformation,extension deformation,volumetric deformation,and quasi acceleration,which are the distribution characteristics of variation,are studied by using the information split before the Lijiang earthquake with MS7.0(February 3,1996)in the north of the Dianxi(western Yunnan)leveling network.The results indicate that in Dianxi(western Yunnan)area,the acute vertical differential movement of the large-scale deformation velocity high gradient belt and high information norm distribution in the Lijiang,Yongsheng,and its adjacent areas in the middle stage of the 1980s is the reflection展开更多
Results of analysis of variation of cross fault short-baseline and short-range leveling in Western Yunnan Earthquake Test Site (WYETS), results show that among five observation stations of cross fault short-baseline a...Results of analysis of variation of cross fault short-baseline and short-range leveling in Western Yunnan Earthquake Test Site (WYETS), results show that among five observation stations of cross fault short-baseline and short-range leveling in WYETS before the Lijiang MS7.0 Earthquake occurred in February 1996 only Yongsheng observation station (epicentral distance 82 km) located at Chenghai fault shows great variation about one year before the earthquake. And the nearest observation station, Lijiang (epicentral distance 42 km); presents great coseismic variation, but does not show obvious anomalous variation before the earthquake. There are no significant variations related to the earthquake at the other three observation stations. Two methods are used in analysis of the observed data and some valuable results have been obtained.展开更多
基金Joint Seismological Science Foundation of China (198023) and National Natural Science Foundation (40272087).
文摘Lijiang-Daju fault, the seismogenic fault of the 1996 Lijiang M=7.0 earthquake, can be divided into Lijiang-Yuhu segment in the south and Yuhu-Daju segment in the north. The two segments show clear difference in geological tectonics, but have the similar dynamic features. Both normal dip-slip and sinistral strike-slip coexist on the fault plane. This kind of movement started at the beginning of the Quaternary (2.4~2.5 Ma B.P.). As to the tectonic types, the detachment fault with low angle was developed in the Early Pleistocene and the normal fault with high angle only after the Mid-Pleistocene (0.8 Ma B.P.). Based on the horizontal displacements of gullies and the vertical variance of planation surfaces cross the Lijiang-Daju fault at east piedmont of Yulong-Haba range, the average horizontal and vertical slip rates are calculated. They are 0.84 mm/a and 0.70 mm/a since the Quaternary and 1.56 mm/a and 1.69 mm/a since the Mid-Pleistocene. The movements of the nearly N-S-trending Lijiang-Daju fault are controlled not only by the regional stress field, but also by the variant movement between the Yulong-Haba range and Lijiang basin. The two kinds of dynamic processes form the characteristics of seismotectonic environment of occurring the 1996 Lijiang earthquake.
基金This project was sponsored by the "Ninth Five-Year ScienceTechnology Plan" (95-04-04-01-01) of the State Seismological Bureau, China
文摘By using the integral dynamic adjustment of the "segmentation rate," this paper processes the leveling repetition measurement data of the Dianxi(western Yunnan)area since the 1980s,makes the fitting of the velocity surface for vertical deformation with multi-surface function,and splits information of the vertical deformation field.The dynamic evolution of the deformation field and vertical deformation information norm-shear deformation,extension deformation,volumetric deformation,and quasi acceleration,which are the distribution characteristics of variation,are studied by using the information split before the Lijiang earthquake with MS7.0(February 3,1996)in the north of the Dianxi(western Yunnan)leveling network.The results indicate that in Dianxi(western Yunnan)area,the acute vertical differential movement of the large-scale deformation velocity high gradient belt and high information norm distribution in the Lijiang,Yongsheng,and its adjacent areas in the middle stage of the 1980s is the reflection
基金This project was sponsored by the Application Basis Research Foundation of Yunnan Province (97D06), China.
文摘Results of analysis of variation of cross fault short-baseline and short-range leveling in Western Yunnan Earthquake Test Site (WYETS), results show that among five observation stations of cross fault short-baseline and short-range leveling in WYETS before the Lijiang MS7.0 Earthquake occurred in February 1996 only Yongsheng observation station (epicentral distance 82 km) located at Chenghai fault shows great variation about one year before the earthquake. And the nearest observation station, Lijiang (epicentral distance 42 km); presents great coseismic variation, but does not show obvious anomalous variation before the earthquake. There are no significant variations related to the earthquake at the other three observation stations. Two methods are used in analysis of the observed data and some valuable results have been obtained.
