Pn-wave velocity and anisotropy of the western Sichuan and Longmen Mountain region, China
详细信息 查看全文
- 作者：Yi Xu (1)
ZhiWei Li (1)
RunQiu Huang (2)
JianHua Liu (1)
JinSong Liu (1) - 关键词：western Sichuan ; Longmen Mountain ; Pn velocity ; anisotropy ; Wenchuan earthquake
- 刊名：Science China Earth Sciences
- 出版年：2010
- 出版时间：November 2010
- 年：2010
- 卷：53
- 期：11
- 页码：1665-1670
- 全文大小：1997KB
- 参考文献：1. Wang W M, Zhao L F, Li J, et al. Rupture process of the / M s8.0 Wenchuan earthquake of Sichuan, China (in Chinese). Chin J Geophys, 2008, 51: 1403鈥?410
2. Zhang Y, Feng W P, Xu L S, et al. Spatio-temporal rupture process of the 2008 great Wenchuan earthquake. Sci China Ser D-Earth Sci, 2009, 52: 145鈥?54 CrossRef
3. Zhang P Z, Xu X W, Wen X Z, et al. Slip rates and reoccurrence intervals of the Longmen Shan active fault zone, tectonic implications for the mechanism for the May 12 Wenchuan earthquake, 2008, Sichuan, China (in Chinese). Chin J Geophys, 2008, 51: 1066鈥?073
4. Burchfiel B C, Royden L H, van der Hilst R D, et al. A geological and geophysical context for the Wenchuan earthquake of 12 May 2008, Sichuan, People鈥檚 Republic of China. GSA Today, 2008, 18: 4鈥?1, doi: 10.1130/GSATG 18A.1 CrossRef
5. Chen Z, Burchfiel B C, Lin Y, et al. Global Positioning System measurements from eastern Tibet and their implications for India/Eurasia intercontinental deformation. J Geophys Res, 2000, 105: 16215鈥?6227 CrossRef
6. Shen Z K, Lu J, Wang M, et al. Contemporary crustal deformation around the southeast borderland of the Tibetan Plateau. J Geophys Res, 2005, 110: B11409, doi: 10.1029/2004JB003421 CrossRef
7. Clark M K, Royden L H. Topographic ooze: Building the eastern margin of Tibet by lower crustal flow. Geology, 2000, 28: 703鈥?06 CrossRef
8. Cook K L, Royden L H. The role of crustal strength variations in shaping orogenic plateaus, with application to Tibet. J Geophys Res, 2008, 113: B08407, doi: 10.1029/2007JB005457 CrossRef
9. Chen J H, Liu Q Y, Li S C, et al. Seismotectonic study by relocation of the Wenchuan / M s8.0 earthquake sequence (in Chinese). Chin J Geophys, 2009, 52: 390鈥?97
10. Liu Q Y, Li Y, Chen J H, et al. Wenchuan / M s 8.0 earthquake: preliminary study of the S-wave velocity structure of the crust and upper mantle (in Chinese). Chin J Geophys, 2009, 52: 309鈥?19
11. Xu Y, Huang R Q, Li Z W, et al. S-wave velocity structure of the Longmen Shan and Wenchuan earthquake area (in Chinese). Chin J Geophys, 2009, 52: 329鈥?38
12. Wang C Y, Lou H, L眉 Z Y, et al. S-wave crustal and upper mantle鈥檚 velocity structure in the eastern Tibetan Plateau-Deep environment of lower crustal flow. Sci China Ser D-Earth Sci, 2008, 51: 263鈥?74 CrossRef
13. Zhao G Z, Chen X B, Wang L F, et al. Evidence of crustal 鈥榗hannel flow鈥?in the eastern margin of Tibetan Plateau from MT measurements. Chin Sci Bull, 2008, 53: 1887鈥?893 CrossRef
14. Wang X B, Zhu Y T, Zhao X K, et al. Deep conductivity characteristics of the Longmen Shan, Eastern Qinghai-Tibet Plateau (in Chinese). Chin J Geophys, 2009, 52: 564鈥?71
15. Guo B, Liu Q Y, Chen J H, et al. Teleseismic P-wave tomography of the crust and upper mantle in Longmenshan area, west Sichuan (in Chinese). Chin J Geophys, 2009, 52: 346鈥?55
16. Li C, van der Hilst R D, Toksoz M N. Constraining spatial variations in P-wave velocity in the upper mantle beneath SE Asia. Phys Earth Planet Inter, 2006, 154: 180鈥?95 CrossRef
17. Huang J, Zhao D. High-resolution mantle tomography of China and surrounding regions. J Geophys Res, 2006, 111: B09305, doi:10.1029/2005 JB004066 CrossRef
18. Huang J L, Song X D, Wang S Y. Fine structure of Pn velocity beneath Sichuan-Yunnan region. Sci China Ser D-Earth Sci, 2003, 46(Suppl II): 201鈥?09
19. Wang C Y, Chan W W, Mooney W D. Three-dimensional velocity structure of crust and upper mantle in southwestern China and its tectonic implications. J Geophys Res, 2003, 108(B9): 2442, doi:10.1029/2002JB001973. CrossRef
20. Liu Y K, Chang Xu, He J K, et al. Three-dimensional velocity images of the crust and upper mantle beneath the north-south zone in China. Bull Seismol Soc Amer, 2005, 95: 916鈥?25, doi: 10.1785/0120010130 CrossRef
21. Liang C T, Song X D. A low velocity belt beneath northern and eastern Tibetan Plateau from Pn tomography. Geophys Res Lett, 2006, 33: L22306, doi: 10.1029/2006GL027926 CrossRef
22. Hearn T M. Anisotropic Pn tomography in the western United States. J Geophys Res, 1996, 101(B4): 8403鈥?414 CrossRef
23. Wang C Y, Han W B, Wu J P, et al. Crustal structure beneath the Songpan-Garze oroenic belt (in Chinese). Acta Seismol Sin, 2003, 25: 229鈥?41
24. Wang C Y, Wu J P, Lou H, et al. P-wave crustal velocity structure in western Sichuan and eastern Tibetan region. Sci China Ser D-Earth Sci, 2003, 46: 254鈥?65
25. Chang L J, Wang C Y, Ding Z F. Seismic anisotropy of upper mantle in Sichuan and adjacent regions. Sci China Ser D-Earth Sci, 2008, 51: 1683鈥?693 CrossRef
26. Xu Y, Li Z W, Hao T Y, et al. Pn wave velocity and anisotropy in the northeastern South China Sea and adjacent region (in Chinese). Chin J Geophys, 2007, 50: 1473鈥?479
27. Xu Y, Li Z W, Liu J S, et al. Pn wave velocity and anisotropy in the Yellow Sea region (in Chinese). Chin J Geophys, 2008, 51: 1444鈥?450 - 作者单位：Yi Xu (1)
ZhiWei Li (1)
RunQiu Huang (2)
JianHua Liu (1)
JinSong Liu (1)
1. Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Science, Beijing, 100029, China
2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, 610059, China - ISSN：1869-1897
文摘
Pn-wave velocity and anisotropy beneath the western Sichuan and adjacent region are inverted by a tomography method using arrival data from earthquakes recorded by the Sichuan Earthquake Network. It is followed by an analysis of the uppermost mantle structure of the Longmen Mountain region and the deep tectonics of the M s8.0 earthquake in Wenchuan. Our results reveal a prominent velocity contrast across the Longmenshan fault: low velocities in the Songpan-Ganzi mountain range and high velocities in the Sichuan basin. They indicate that the Songpan-Ganzi mountain range is underlain by a weak uppermost mantle, which is easy to create ductile flow, whereas the Sichuan basin has a mechanically strong uppermost mantle. These features reflect a difference of the lithospheric mantle beneath tectonically active mountain range and stable basin. The boundary between the high and low velocities is coincident with the Longmenshan fault. Bordered by Wenchuan, the northern part of the boundary is parallel to the fault belt and aftershock distribution, but the southern part of the boundary deviates from the fault belt and is bent toward the Sichuan basin. The M s8.0 earthquake in Wenchuan is located at the flexural part between them, where a strong heterogeneity is shown in the velocity variation across and parallel to the boundary. This area is reasonably believed as a potential location for regional stress accumulation and release in the Longmen Mountain region, reflecting a prominent character in the deep structure around Wenchuan. Pn-wave anisotropy reveals the mantle flow that is consistent with the eastward movement of the Tibetan Plateau. This process provided deep dynamic sourse for tectonic deformation in the Longmen Mountain region and for the occurrence of the Wenchuan M s8.0 earthquake, but it is clearly affected by the strong lithosphere of the Sichuan basin. There is no correlation between the Pn-wave anisotropy and the Longmenshan fault, hence, this fault system is only restricted within the crust. However, the mantle flow beneath the southeastern Tibetan Plateau shows a clockwise rotation along the Xianshuihe fault. We infer that these two fault systems may be controlled by different deep dynamics.