1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 Earthquake Administration of Yunnan Province, Kunming 650224, China
Crustal structure in Xiaojiang fault zone and its vicinity
1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 Earthquake Administration of Yunnan Province, Kunming 650224, China
摘要Based on the integrative interpretation of travel-time data and amplitude information obtained from the deep seismic sounding experiment on the Chuxiong-Luoping profile, eastern Yunnan province, carried out in January of 2005, we present a 2-D P wave velocity structure along the profile. The crustal structure shows remarkable contrasts between the two sides of the Xiaojiang fault zone, although the whole profile is situated within the Yangtze platform. The average P wave velocities of the crust on the west and east sides of the fault zone are 6.21 km/s and 6.32 km/s, respectively, and the crustal thicknesses are 41 km and 45 km, respectively. These results imply that the crust to the east of the Xiaojiang fault zone presents characteristics of crustal structure in a stable platform, while the crust to the west is complicated with a lower velocity zone in middle of the upper crust. The average velocity of 6.21 km/s is lower than the global continental crustal average (6.30 km/s), indicating that the region is tectonically active. According to the lateral variation of velocity and depth of interfaces (including the Moho), it is inferred that the Xiaojiang fault zone has cut through the whole crust. It is also deduced that existence of low velocity zone in middle of the upper crust is conducive to the south-southeastern sliding of the Sichuan- Yunnan (Chuan-Dian) rhombus block.
Abstract:Based on the integrative interpretation of travel-time data and amplitude information obtained from the deep seismic sounding experiment on the Chuxiong-Luoping profile, eastern Yunnan province, carried out in January of 2005, we present a 2-D P wave velocity structure along the profile. The crustal structure shows remarkable contrasts between the two sides of the Xiaojiang fault zone, although the whole profile is situated within the Yangtze platform. The average P wave velocities of the crust on the west and east sides of the fault zone are 6.21 km/s and 6.32 km/s, respectively, and the crustal thicknesses are 41 km and 45 km, respectively. These results imply that the crust to the east of the Xiaojiang fault zone presents characteristics of crustal structure in a stable platform, while the crust to the west is complicated with a lower velocity zone in middle of the upper crust. The average velocity of 6.21 km/s is lower than the global continental crustal average (6.30 km/s), indicating that the region is tectonically active. According to the lateral variation of velocity and depth of interfaces (including the Moho), it is inferred that the Xiaojiang fault zone has cut through the whole crust. It is also deduced that existence of low velocity zone in middle of the upper crust is conducive to the south-southeastern sliding of the Sichuan- Yunnan (Chuan-Dian) rhombus block.
基金资助:the project “Exploration of Active Seismic Faults in Large Cities and Earthquake risk Assessment” and National Natural Science Foundation of China (Grant No. 40774037)
通讯作者:
Chunyong Wang
E-mail: wangcy@cea-igp.ac.cn
引用本文:
Chunyong Wang, Hai Lou, Xili Wang, Jiazheng Qin, Runhai Yang, Jinming Zhao. Crustal structure in Xiaojiang fault zone and its vicinity[J]. 《地震学报》英文版, 2009, 22(4): 347-356.
Chunyong Wang, Hai Lou, Xili Wang, Jiazheng Qin, Runhai Yang, Jinming Zhao. Crustal structure in Xiaojiang fault zone and its vicinity. Earthquake Science, 2009, 22(4): 347-356.