Crustal block rotations in Chinese mainland revealed by GPS measurements
Wei Wang1, 2, Shaomin Yang1, 3, Qi Wang1, 3
1 Institute of Seismology, China Earthquake Administration, Wuhan 430071, China 2 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 3 Research Center of Space Science and Technology, China University of Geosciences, Wuhan 430074, China
Crustal block rotations in Chinese mainland revealed by GPS measurements
Wei Wang1, 2, Shaomin Yang1, 3, Qi Wang1, 3
1 Institute of Seismology, China Earthquake Administration, Wuhan 430071, China 2 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 3 Research Center of Space Science and Technology, China University of Geosciences, Wuhan 430074, China
摘要We simulate GPS horizontal velocity field in terms of rotations of crustal blocks to describe deformation behavior of the Chinese mainland and its neighboring areas. 31 crustal blocks are bounded primarily by ~30 Quaternary faults with distinct geometries and variable long-term rates of <20 mm/a, and 1 683 GPS velocities were determined from decade-long observations mostly with an averaged uncertainty of 1-2 mm/a. We define GPS velocity at a site by the combination of motion of rigid block and elastic strain induced by the fault that is locking during a seismic cycle. Model velocities predicted from the preferable block model match well with the GPS velocities to an uncertainty of ~1.7 mm/a. The slip rates inferred from this model is in a range of 6-18 mm/a for the major faults in Tibet and its margins and 1-4 mm/a in eastern China, consistent with geological observations. Our numerical simulation suggests that the crustal blocks deform internally at a level of ~10×10-9/a, quite small in comparison with significant deformation localized along fault zones of 50-100 km wide. We conclude that the pattern of continental deformation is not continuous-like but block-like, and the tenet of plate tectonics may be applicable to characterize the active deformation in Asia.
Abstract：We simulate GPS horizontal velocity field in terms of rotations of crustal blocks to describe deformation behavior of the Chinese mainland and its neighboring areas. 31 crustal blocks are bounded primarily by ~30 Quaternary faults with distinct geometries and variable long-term rates of <20 mm/a, and 1 683 GPS velocities were determined from decade-long observations mostly with an averaged uncertainty of 1-2 mm/a. We define GPS velocity at a site by the combination of motion of rigid block and elastic strain induced by the fault that is locking during a seismic cycle. Model velocities predicted from the preferable block model match well with the GPS velocities to an uncertainty of ~1.7 mm/a. The slip rates inferred from this model is in a range of 6-18 mm/a for the major faults in Tibet and its margins and 1-4 mm/a in eastern China, consistent with geological observations. Our numerical simulation suggests that the crustal blocks deform internally at a level of ~10×10-9/a, quite small in comparison with significant deformation localized along fault zones of 50-100 km wide. We conclude that the pattern of continental deformation is not continuous-like but block-like, and the tenet of plate tectonics may be applicable to characterize the active deformation in Asia.
基金资助:the National Natural Science Foundation of China (No. 40674054, 40774014 and 40974012), and Foundation of Institute of Seismology CEA (IS200856059)
通讯作者:
Wei Wang
E-mail: wangweigps@126.com.
引用本文:
Wei Wang, Shaomin Yang, Qi Wang. Crustal block rotations in Chinese mainland revealed by GPS measurements[J]. 《地震学报》英文版, 2009, 22(6): 639-649.
Wei Wang, Shaomin Yang, Qi Wang. Crustal block rotations in Chinese mainland revealed by GPS measurements. Earthquake Science, 2009, 22(6): 639-649.
