PAN Jia-Tie,
LI Yong-Hua,
WU Qing-Ju et al
.2015.Phase velocity maps of Rayleigh waves in the southeast Tibetan plateau.Chinese Journal Of Geophysics,58(11): 3993-4006,doi: 10.6038/cjg20151109
Phase velocity maps of Rayleigh waves in the southeast Tibetan plateau
PAN Jia-Tie, LI Yong-Hua, WU Qing-Ju, DING Zhi-Feng
Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;Key Laboratory of Seismic Observation and Geophysical Imaging, Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
Abstract：The southeast Tibetan plateau is located in the transition zone between the uplift plateau and the stable Yangtze block. Many volcanoes, deep and huge faults, strong earthquakes are developed in this region. The crustal and upper mantle structure is very complex here. Investigating the detail velocity structure beneath this region is very important when studying the deformation mechanism of intra-plate volcano, the seismicity in the Yunnan-Sichuan area, the breeding environment of strong earthquakes and the dynamics of Tibet plateau uplift.#br#The ballistic surface wave tomography is a classic method of studying the crustal and upper mantle structure. By collecting the vertical component of teleseismic data recorded by 325 broadband stations of the portable seismic array under the project "China Seismic Array-Phase 1" during Aug. 2011 and Sep. 2012, a total number of 3594 inter-station phase velocity dispersion curves of Rayleigh waves were determined by a frequency-time analysis method based on a continuous wavelet transform. In addition, all of dispersion curves were arranged into a tomographic inversion scheme, called Ditmar & Yanovskaya, to obtain the phase velocity maps ranging from 10 s to 60 s in the southeast Tibetan plateau. #br#The spatial resolution maps show that the lateral resolution is about 50 km. Our tomographic results reveal that the S-wave structure of the crust and upper mantle beneath the SE Tibet is obviously laterally heterogeneous. At short periods (e.g., 10 s), the distribution of phase velocity has good relationship with the sediment layer thickness on the surface. Most of strong earthquakes occurred in low-speed regions or the evident gradient belts where the velocities change from high to low values on the map of 15 s, revealing that the strong earthquakes are directly related to the velocity structure of middle and upper crust. At the intermediate periods (e.g., 20 s, 30 s), the distribution of phase velocity is related well with the crustal thickness. The obvious low-speed zone imaged beneath the Xiaojiang fault and Songpan-Ganzi block on the maps of intermediate periods may reveal there are low-velocity layers in the middle-lower crust which are also found by previous studies. At the longer periods (e.g., 40 s, 60 s), the distribution of phase velocity is related well with the thermal structure and tectonic activity (e.g. magmatic activity) in the upper mantle. A large low-velocity zone is imaged in west Yunnan province, indicating partial melts might exist in the upper mantle beneath this area. #br#It has different velocity characteristics on the phase velocity maps beneath different tectonic units. It is common that low-velocity zones between 10 s and 60 s are present beneath the Tengchong volcano, especially, it is much slower for the phase velocity speeding up as periods increasing after 40 s, and it becomes the lowest velocity zone for the Tengchong volcano than any other blocks, indicating that the low-velocity layer may extend down to the upper mantle (~100 km) at least beneath the Tengchong volcano.
Avouac J P, Tapponnier P. 1993. Kinematic model of active deformation in central Asia. Geophys. Res. Lett., 20(10): 895-898. Backus G, Gilbert F. 1968. The resolving power of gross Earth data. Geophys. J. Int., 16(2): 169-205. Bai D H, Meju M A, Liao Z J. 2001. Magnetotelluric images of deep crustal structure of the Rehai geothermal field near Tengchong, Southern China. Geophys. J. Int., 147(3): 677-687. Bai D H, Unsworth M J, Meju M A, et al. 2010. Crustal deformation of the eastern Tibetan Plateau revealed by magnetotelluric imaging. Nat. Geosci., 3(5): 358-362. Bai Z M, Wang C Y. 2003. Tomographic investigation of the upper crustal structure and seismotectonic environments in Yunnan province. Acta Seismologica Sinica (in Chinese), 25(2): 117-127. Chen B W, Wang K Y, Liu W X, et al. 1987. The Geotectonics Beneath Nujiang-Lancangjiang-Jinsha River Region (in Chinese). Beijing: Geological Publishing House, 204. Chen C H, Wang W H, Teng T L. 2001. 3D velocity structure around the source area of the 1999 Chi-Chi, Taiwan, earthquake: Before and after the mainshock. Bull. Seismol. Soci. Amer., 91(5): 1013-1027. Clark M K, Royden L H. 2000. Topographic ooze: building the eastern margin of Tibet by lower crustal flow. Geology, 28(8): 703-706. Ditmar P G, Yanovskaya T B. 1987. Generalization of Backus Gilbert method for estimation of lateral variations of surface wave velocities. Izv. Phys. Solid Earth., 23(6): 470-477. He Z Q, Su W, Ye T L. 2004. Seismic tomography of Yunnan region using short-period surface wave phase velocity. Acta Seismologica Sinica (in Chinese), 26(6): 583-590. Hu H X, Lu H X, Wang C Y, et al. 1986. Explosion investigation of the crustal structure in western Yunnan Province. Acta Geophysica Sinica (in Chinese), 29(2): 133-144. Hu J F, Su Y J, Zhu X G, et al. 2003. S-wave velocity and Poisson's ratio structure of crust in Yunnan and its implication. Science in China Series D: Earth Sciences, 48(2): 210-218. Hu J F, Zhu X G, Xia J Y, et al. 2005. Using surface wave and receiver function to jointly inverse the crust-mantle velocity structure in the West Yunnan area. Chinese J. Geophys. (in Chinese), 48(5): 1069-1076, doi: 10.3321/j.issn:0001-5733.2005.05.013. Huang J, Liu X J, Su Y J, et al. 2012. Imaging 3-D crustal P-wave velocity structure of western Yunnan with bulletin data. Earthq. Sci., 25(2): 151-160. Huang J L, Zhao D P, Zheng S H. 2002. Lithospheric structure and its relationship to seismic and volcanic activity in southwest China. J. Geophys. Res., 107(B10): ESE13-1-ESE13-14, doi: 10.1029/2000JB000137. Huang K N, Opdyke N D. 1993. Paleomagnetic results from Cretaceous and Jurassic rocks of South and Southwest Yunnan: evidence for large clockwise rotations in the Indochina and Shan-Thai-Malay terrenes. Earth Planet Sci. Lett., 117(3-4): 507-524. Huang Z X, Su W, Peng Y J, et al. 2003. Rayleigh wave tomography of China and adjacent regions. J. Geophys. Res., 108(B2): 2073, doi: 10.1029/2001JB001696. Huang Z X, Li H Y, Xu Y. 2013. Lithospheric S-wave velocity structure of the North-South Seismic Belt of China from surface wave tomography. Chinese J. Geophys. (in Chinese), 56(4): 1121-1131. doi: 10.6038/cjg20130408. Jiang C S. 1998. Distribution characteristics of Tengchong volcano in the Cenozoic era. J. Seismol. Res. (in Chinese), 21(4): 309-319. Kan R J, Wang S J, Huang K, et al. 1983. Modern tectonic stress field and relative motion of intraplate block in southwestern China. Seismology and Geology (in Chinese), 5(2): 79-90. Kan R J, Lin Z Y. 1986. A preliminary study on crustal and upper mantle structures in Yunnan. Earthq. Res. China (in Chinese), 2(4): 50-61. Kan R J, Han Y. 1992. The Specification of Geoscience Transect from Zhefang to Malong, Yunnan Province (in Chinese). Beijing: Seismological Press: 1-20. Kennett B L N, Engdahl E R, Buland R. 1995. Constraints on seismic velocities in the Earth from traveltimes. Geophys. J. Int., 122(1): 108-124. Kong X R, Liu S J, Dou Q C, et al. 1987. Electrical conductivity structure in the crust and upper mantle in the region of Pan-xi rift. Chinese J. Geophys. (in Chinese), 30(2): 136-143. Lei J S, Zhao D P, Su Y J. 2009. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res., 114(B5): B05302, doi: 10.1029/2008JB005881. Li Y H, Wu Q J, Tian X B, et al. 2009. Crustal structure in the Yunnan region determined by modeling receiver functions. Chinese J. Geophys. ( in Chinese), 52(1): 67-80. Li Y H, Pan J T, Wu Q J, et al. 2014a. Crustal and uppermost mantle structure of SE Tibetan plateau from Rayleigh-wave group-velocity measurements. Earthq. Sci., 27(4): 411-419. Li Y H, Gao M T, Wu Q J. 2014b. Crustal thickness map of the Chinese mainland from teleseismic receiver functions. Tectonophysics, 611: 51-60. Li Y H, Xu X M, Zhang E H, et al. 2014c. Three-Dimensional crust structure beneath SE Tibetan Plateau and its seismotectonic implications for the Ludian and Jinggu earthquakes. Seismology and Geology (in Chinese), 36(4): 1204-1216. Lin Z Y, Hu H X, Zhang W B, et al. 1993. A study on velocity structure of the crust and upper mantle in western Yunnan region. Acta Seismologica Sinica (in Chinese), 15(4): 427-440. Lu L Y, He Z Q, Ding Z F, et al. 2014. Azimuth anisotropy and velocity heterogeneity of Yunnan area based on seismic ambient noise. Chinese J. Geophys. (in Chinese), 57(3): 822-836, doi: 10.6038/cjg20140312. Ma X B, Kong X R, Liu H B, et al. 2001. Magnetotelluric sounding results in eastern Tibetan Plateau. Science in China Series D: Earth Sciences, 44(1): 79-85. Mao Y P, Han X M. 2003. The Research of Strong Earthquakes (M≥6) in Yunnan (in Chinese). Kunming: Yunnan Science and Technology Press, 1-10. Pan J T, Wu Q J, Li Y H, et al. 2011. Rayleigh wave tomography of the phase velocity in North China. Chinese J. Geophys. (in Chinese), 54(1): 67-76. doi: 10.3969/j.issn.0001-5733.2011.01.008. Pan J T, Wu Q J, Li Y H, et al. 2014a. Ambient noise tomography in northeast China. Chinese J. Geophys. (in Chinese), 57(3): 812-821, doi: 10.6038/cjg20140311. Pan J T, Li Y H, Wu Q J, et al. 2014b. 3-D S-wave velocity structure of crust and upper-mantle beneath the northeast China. Chinese J. Geophys. (in Chinese), 57(7): 2077-2087, doi: 10.6038/cjg20140705. Qian X D, Qing J Z. 2000. Seismic types occurred in volcano area of Tengchong, Yunnan. Earthq. Res. Sichuan (in Chinese), (3): 43-48. Ritzwoller M H, Levshin A L. 1998. Eurasian surface wave tomography: Group velocities. J. Geophys. Res., 103(B3): 4839- 4878. Royden L H, Burchfiel B C, King R W, et al. 1997. Surface deformation and lower crustal flow in eastern Tibet. Science, 276(5313): 788-790. Sun J, Xu C F, Jiang Z, et al. 1989. The electrical structure of the crust and upper mantle in the west part of Yunnan province and its relation to crustal tectonic. Seismology and Geology (in Chinese), 11(1): 35-45. Tapponnier P, Peltzer G, Le Dain A Y, et al. 1982. Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine. Geology, 10(12): 611-616. Tapponnier P, Peltzer G, Armijo R. 1986. On the mechanics of the collision between India and Asia. London: Geological Society Special Publications, 19: 115-157. Wang C Y, Lou H, Wu J P, et al. 2002. Seismological study on the crustal structure of Tengchong volcano-geothermal area. Acta Seismologica Sinica (in Chinese), 24(3): 231-242. Wang C Y, Chan W W, Mooney W D. 2003. Three-dimensional velocity structure of crust and upper mantle in southwestern China and its tectonic implications. J. Geophys. Res., 108(B9), doi: 10.1029/2002JB001973. Wang C Y, Lou H, LÜ Z Y, et al. 2008. S-wave crustal and upper mantle's velocity structure in the eastern Tibetan Plateau-Deep environment of lower crustal flow. Science in China Series D: Earth Sciences, 51(2): 263-274. Wang F Y, Pan S Z, Liu L, et al. 2014. Wide angle seismic exploration of Yuxi-Lincang profile—The research of crustal structure of the red river fault zone and southern Yunnan. Chinese J. Geophys. (in Chinese), 57(10): 3247-3258, doi: 10.6038/cjg20141013. Wang Q, Gao Y. 2014. Rayleigh wave phase velocity tomography and strong earthquake activity on the southeastern front of the Tibetan Plateau. Science China Earth Sciences, 57(10): 2532-2542. Wang W L, Wu J P, Fang L H, et al. 2014. S wave velocity structure in southwest China from surface wave tomography and receiver functions. J. Geophys. Res., 119(2): 1061-1078, doi: 10.1002/2013JB010317. Wang X B, Yu N, Zhu Y T, et al. 2008. Preliminary result of magnetotelluric sounding in the Longmen thrust belt of west Sichuan, China. J. Chengdu Univ. Technol. (Sci. Technol. Ed.) (in Chinese), 35(4): 398-403. Wang Y. 2012. Thermal state and strength of the lithosphere beneath the Chinese mainland. Acta Geologica Sinica, 86(4): 810-827. Wei W, Xu J D, Zhao D P, et al. 2012. East Asia mantle tomography: New insight into plate subduction and intraplate volcanism. J. Asian Earth Sci., 60: 88-103. Wu F T, Levshin A L. 1994. Surface-wave group velocity tomography of East Asia. Phys. Earth. Planet. Inter., 84(1-4): 59-77. Wu J P, Ming Y H, Wang C Y, et al. 2001. The S wave velocity structure beneath digital seismic stations of yunnan province inferred from teleseismic receiver function modelling. Chinese J. Geophys. (in Chinese), 44(2): 228-237, doi: 10.3321/j.issn:0001-5733.2001.02.010. Wu Q J, Zheng X F, Pan J T, et al. 2009. Measurement of interstation phase velocity by wavelet transformation. Earthq. Sci., 22(4): 425-429. Xiong S B, Zheng Y, Yin Z X, et al. 1993. The 2-D structure and its tectonic implication of the crust in the Lijiang-Panzhihua-Zhehai region. Chinese J. Geophys. (in Chinese), 36(4): 434-444. Xu M J, Wang L S, Liu J H, et al. 2006. Crust and uppermost mantle structure of the Ailaoshan-Red River fault from receiver function analysis. Science in China Series D: Earth Sciences, 49(10): 1043-1052. Xu X W, Deng Q D. 1996. Nonlinear characteristics of Paleoseismicity in China. J. Geophys. Res., 101(B3): 6209-6231. Yang X T, Xu Y, Liu J H, et al. 2011. Seismic tomography in the Tengchong volcanic area and its tectonic implication. Chinese J. Geophys. (in Chinese), 54(8): 2050-2059, doi: 10.3969/j.issn.0001-5733.2011.08.012. Yang Y J, Zheng Y, Chen J, et al. 2010. Rayleigh wave phase velocity maps of Tibet and the surrounding regions from ambient seismic noise tomography. Geochem. Geophys. Geosyst., 11(8): Q08010, doi: 10.1029/2010GC003119. Yang Y J, Ritzwoller M H, Zheng Y, et al. 2012. A synoptic view of the distribution and connectivity of the mid-crustal low velocity zone beneath Tibet. J. Geophys. Res., 117(B4): B04303. doi: 10.1029/2011JB008810. Yanovskaya T B, Ditmar P G. 1990. Smoothness criteria in surface wave tomography. Geophys. J. Int., 102(1): 63-72. Yao H J, Van Der Hilst R D, De Hoop M V. 2006. Surface-wave array tomography in SE Tibet from ambient seismic noise and two-station analysis—I. Phase velocity maps. Geophys. J. Int., 166(2): 732-744. Yao H J, Beghein C, van der Hilst R D. 2008. Surface wave array tomography in SE Tibet from ambient seismic noise and two station analysis—II. Crustal and upper-mantle structure. Geophys. J. Int., 173(1): 205-219. Yin A, Harrison T M. 2000. Geologic Evolution of the Himalayan-Tibetan Orogen. Annu. Rev. Earth Planet. Sci., 28: 211-280. Zeng R S, Song Z A. 1963. Phase velocity of Rayleigh waves in China. Chinese J. Geophys. (in Chinese), 12(2): 148-165. Zhang Z, Chen Y, Li F. 2008. Reconstruction of the S-wave velocity structure of crust and mantle from seismic surface wave dispersion in Sichuan-Yunnan region. Chinese J. Geophys. (in Chinese), 51(4): 1114-1122. Zhang Z J, Bai Z M, Wang C Y, et al. 2005a. The crustal structure under Sanjiang and its dynamic implications: Revealed by seismic reflection/refraction profile between Zhefang and Binchuan, Yunnan. Science in China Series D: Earth Sciences, 48(9): 1329-1336. Zhang Z J, Bai Z M, Wang C Y, et al. 2005b. Crustal structure of Gondwana- and Yangtze-typed blocks: An example by wide-angle seismic profile from Menglian to Malong in western Yunnan. Science in China Series D: Earth Sciences, 48 (11): 1828-1836. Zhao D P, Kanamori H, Negishi H, et al. 1996. Tomography of the source area of the 1995 Kobe earthquake: Evidence for fluids at the hypocenter. Science, 274(5294): 1891-1894. Zhao D P, Ochi F, Hasegawa A, et al. 2000. Evidence for the location and cause of large crustal earthquakes in Japan. J. Geophys. Res., 105(B6): 13579-13594. Zheng D C, Ge Z X, Yang R H, et al. 2014. Broadband ambient noise tomography in Yunnan Province. Acta Seismologica Sinica (in Chinese), 36 (4): 602-614. Zhou L Q, Xie J Y, Shen W S, et al. 2012. The structure of the crust and uppermost mantle beneath South China from ambient noise and earthquake tomography. Geophys. J. Int., 189(3): 1565-1583. Zhou Z H, Xiang C Y, Deng W M. 1997. Lithospheric geothermal structure in Yunnan, China. Earthq. Res. China (in Chinese), 13(3): 213-223. Zhu L B, Xu Q, Chen X F. 2002. Group velocity of Rayleigh wave in Chinese Continent and its adjacent seas. Chinese J. Geophys. (in Chinese), 45(4): 475-482.
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