The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Qu...The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Quaternary is of fundamental importance for understanding the future seismic risk of the fault zone or even the entire western Sichuan region. Using the methods of detailed geomorphic and geological survey, digital image analysis, total station instrument survey, excavation of combined trench and dating, we analyze the geomorphologic sequences of the offset strata at several sites where the late Quaternary deformation remnants are fairly well preserved and obtain some new results as follows: Strong earthquake events with left-lateral displacements of about 3 m occurred at the two sites of Zimakua and Yejitong at 1634-1811, 1030-1050 and 280-550 a BP, respectively, and the recurrence interval is 520-660 a; The youngest event in the area of Dahaizi-Ganhaizi should be the earthquake of 1536, other events are at 1768-1826, 2755-4108 and 4108-6593 a BP, respectively, with a recurrence interval of 1300-1900 a. The strong earthquake activity shows a clustering character. The possibility of occurrence of a strong earthquake exists on the north segment of the Anninghe fault sometime in the future.展开更多
Through integrated analyses of time-varying patterns of regional seismicity, occurrence background of strong and large historical earthquakes along active faults, and temporal-spatial distribution of accurately reloca...Through integrated analyses of time-varying patterns of regional seismicity, occurrence background of strong and large historical earthquakes along active faults, and temporal-spatial distribution of accurately relocated hypocenters of modern small earthq展开更多
The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local historical record shows that a M2≥7 strong earthquake occurred in the year of 1536. On the basis of the det...The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local historical record shows that a M2≥7 strong earthquake occurred in the year of 1536. On the basis of the detailed air-photographic interpretation and field investigation, we have acquired the following knowledge： ① The average sinistral strike-slip rate since the Late Pleistocene is about 3～7 mm/a; ② There is important reverse faulting along the fault zone besides the main left-lateral strike-slip motion, and the shortening rate across the Anninghe fault zone due to the reverse faulting is about 1.7-4.0 mm/a. If the Xianshuihe fault zone is simply partitioned into the Anninghe and Daliangshan faults, we can also get a slip rate of 3-7 mm/a along the Daliangshan fault zone, which is the same as that on the Anninghe fault zone. Moreover, on the basis of our field investigation and the latest knowledge concerning the active tectonics of Tibetan crust, we create a dynamic model for the Anninghe fault zone.展开更多
Based on fault geometric features,composite pattern,faulting land-forms and seismic data,this paper discussed the activity behavior along the northern segment of the Anninghe fault(from Xichang to Shimian)since the La...Based on fault geometric features,composite pattern,faulting land-forms and seismic data,this paper discussed the activity behavior along the northern segment of the Anninghe fault(from Xichang to Shimian)since the Late Pleistocene.The fault can be divided into three active segments by discrepancies of their activity:the segment from Xichang to Mianning,the segment from Mianning to Zimakua,and the segment from Zimakua to Tianwan.The southern segment has the background of occurrence of great earthquakes,but the middle and the northern segments can generate strong and moderate events respectively.According to the features of quartz from fault gouges by scanning electron microscopy(SEM),this paper discussed the movement features along the fault and indicated the stick-slipping feature on the segment from Xichang to Zimakua,the creeping feature on the segment from Jiziping to Tianwan and the transitional feature on the segment in between.展开更多
基金the National Basic Research Program of China (Grant No. 2004CB418401)
文摘The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Quaternary is of fundamental importance for understanding the future seismic risk of the fault zone or even the entire western Sichuan region. Using the methods of detailed geomorphic and geological survey, digital image analysis, total station instrument survey, excavation of combined trench and dating, we analyze the geomorphologic sequences of the offset strata at several sites where the late Quaternary deformation remnants are fairly well preserved and obtain some new results as follows: Strong earthquake events with left-lateral displacements of about 3 m occurred at the two sites of Zimakua and Yejitong at 1634-1811, 1030-1050 and 280-550 a BP, respectively, and the recurrence interval is 520-660 a; The youngest event in the area of Dahaizi-Ganhaizi should be the earthquake of 1536, other events are at 1768-1826, 2755-4108 and 4108-6593 a BP, respectively, with a recurrence interval of 1300-1900 a. The strong earthquake activity shows a clustering character. The possibility of occurrence of a strong earthquake exists on the north segment of the Anninghe fault sometime in the future.
基金the National Basic Research Program of China (Grant No. 2004CB418401)
文摘Through integrated analyses of time-varying patterns of regional seismicity, occurrence background of strong and large historical earthquakes along active faults, and temporal-spatial distribution of accurately relocated hypocenters of modern small earthq
基金Joint Seismological Science Foundation of China (105066)National Natural Science Foundation of China (40472109)the SASAKAWA Scientific Grant from the Japan Science Society.
文摘The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local historical record shows that a M2≥7 strong earthquake occurred in the year of 1536. On the basis of the detailed air-photographic interpretation and field investigation, we have acquired the following knowledge： ① The average sinistral strike-slip rate since the Late Pleistocene is about 3～7 mm/a; ② There is important reverse faulting along the fault zone besides the main left-lateral strike-slip motion, and the shortening rate across the Anninghe fault zone due to the reverse faulting is about 1.7-4.0 mm/a. If the Xianshuihe fault zone is simply partitioned into the Anninghe and Daliangshan faults, we can also get a slip rate of 3-7 mm/a along the Daliangshan fault zone, which is the same as that on the Anninghe fault zone. Moreover, on the basis of our field investigation and the latest knowledge concerning the active tectonics of Tibetan crust, we create a dynamic model for the Anninghe fault zone.
文摘Based on fault geometric features,composite pattern,faulting land-forms and seismic data,this paper discussed the activity behavior along the northern segment of the Anninghe fault(from Xichang to Shimian)since the Late Pleistocene.The fault can be divided into three active segments by discrepancies of their activity:the segment from Xichang to Mianning,the segment from Mianning to Zimakua,and the segment from Zimakua to Tianwan.The southern segment has the background of occurrence of great earthquakes,but the middle and the northern segments can generate strong and moderate events respectively.According to the features of quartz from fault gouges by scanning electron microscopy(SEM),this paper discussed the movement features along the fault and indicated the stick-slipping feature on the segment from Xichang to Zimakua,the creeping feature on the segment from Jiziping to Tianwan and the transitional feature on the segment in between.
