Abstract
Focal mechanism and dynamic rupture process of the Wenchaun M s8.0 earthquake in Sichuan province on 12 May 2008 were obtained by inverting long period seismic data from the Global Seismic Network (GSN), and characteristics of the co-seismic displacement field near the fault were quantitatively analyzed based on the inverted results to investigate the mechanism causing disaster. A finite fault model with given focal mechanism and vertical components of the long period P-waves from 21 stations with evenly azimuthal coverage were adopted in the inversion. From the inverted results as well as aftershock distribution, the causative fault of the great Wenchuan earthquake was confirmed to be a fault of strike 225°/dip 39°/rake 120°, indicating that the earthquake was mainly a thrust event with right-lateral strike-slip component. The released scalar seismic moment was estimated to be about 9.4×1020-2.0×1021 Nm, yielding moment magnitude of M w7.9–8.1. The great Wenchuan earthquake occurred on a fault more than 300 km long, and had a complicated rupture process of about 90 s duration time. The slip distribution was highly inhomogeneous with the average slip of about 2.4 m. Four slip-patches broke the ground surface. Two of them were underneath the regions of Wenchuan-Yingxiu and Beichuan, respectively, with the first being around the hypocenter (rupture initiation point), where the largest slip was about 7.3 m, and the second being underneath Beichuan and extending to Pingwu, where the largest slip was about 5.6 m. The other two slip-patches had smaller sizes, one having the maximum slip of 1.8 m and lying underneath the north of Kangding, and the other having the maximum slip of 0.7 m and lying underneath the northeast of Qingchuan. Average and maximum stress drops over the whole fault plane were estimated to be 18 MPa and 53 MPa, respectively. In addition, the co-seismic displacement field near the fault was analyzed. The results indicate that the features of the co-seismic displacement field were coincident with those of the intensity distribution in the meizoseismal area, implying that the large-scale, large-amplitude and surface-broken thrust dislocation should be responsible for the serious disaster in the near fault area.
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References
Chen G G, Ji F J, Zhou R J, et al. Primary research of activity segmentation of Longmenshan fault zone since Late-Quaternary (in Chinese). Seismol Geol, 2007, 29(3): 657–673
Yang Z X, Waldhauser F, Chen Y T, et al. Double-difference relocation of earthquakes in central-western China, 1992–1999. J Seismol, 2005, 9: 241–264
Min Z Q. Historical Strong Earthquake Catalog in China (the 23th Century BC-1911 AD) (in Chinese). Beijing: Seismological Press, 1995. 1–514
Min Z Q. Historical Strong Earthquake Catalog in China (1912 AD-1911 AD) (in Chinese). Beijing: Seismological Press, 1995. 1–636
Zhang Y, Xu L S, Chen Y T, et al. Source process of M s6.4 earthquake in Ning’er, Yunnan in 2007. Sci China Ser D-Earth Sci, 2008, doi: 10.1007/s11430-009-0016-0
Kennett B L N. Seismic Wave Propagation in Stratified Media. Cambridge: Cambridge University Press, 1983. 1–339
Kennett B L N, Engdahl E R. Travel times for global earthquake location and phase identification. Geophys J Int, 1991, 105: 429–465
Zhang Y. Study on the method of earthquake rupture process inversion (in Chinese). Dissertation for Doctor Degree. Beijing: School of Earth and Space Sciences, Peking University, 2008. 1–158
Liu C, Zhang Y, Xu L S, et al. A new technique for moment tensor inversion with applications to the 2008 Wenchuan M s8.0 earthquake sequence (in Chinese). Acta Seismol Sin, 2008, 30(4): 329–339
Kikuchi M, Kanamori H. Inversion of complex body waves. Bull Seism Soc Am, 1982, 72: 491–506
Hartzell S H, Heaton T H. Inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 Imperial Valley, California, earthquake. Bull Seism Soc Am, 1983, 73: 1553–1583
Ward S N, Barrientos S E. An inversion for slip distribution and fault shape from geodetic observations of the 1983, Borah Park, Idaho, earthquake. J Geophys Res, 1986, 91(B5): 4909–4919
Chen Y T, Xu L S. A time domain inversion technique for the tempo-spatial distribution of slip on a finite fault plane with applications to recent large earthquakes in Tibetan Plateau. Geophys J Int, 2000, 143(2): 407–416
Brune J N. Tectonic stress and the spectra of seismic shear waves from earthquakes. J Geophys Res, 1970, 75: 4997–5009
Brune J N. Correction. Tectonic stress and the spectra of seismic shear waves from earthquake. J Geophys Res, 1971, 76: 5002
Kanamori H. Mechanics of earthquakes. Ann Rev Earth Planet Sci, 1994, 22: 207–237
Chen Y T, Lin B H, Lin Z Y, et al. The focal mechanism of the 1966 Hsingtai earthquake as inferred from the ground deformation observations (in Chinese). Chin J Geophys, 1975, 18(3): 164–182
Chen Y T, Huang L R, Lin B H, et al. A dislocation model of the Tangshan earthquake of 1976 from the inversion of geodetic data (in Chinese). Chin J Geophys, 1979, 22(3): 201–216
Okada Y. Surface deformation due to shear and tensile faults in a half-space. Bull Seism Soc Am, 1985, 75(4): 1135–1154
National Wenchuan Earthquake Expert Committee. Earthquake-Geological Disaster Atlas of Wenchuan Earthquake Area. Beijing: SinoMaps Press, 2008. 1–105
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Supported by the National Basic Research Program of China (Grant No. 2004CB418404-4) and the National Natural Science Foundation of China (Grant Nos. 40574025 and 40874026)
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Zhang, Y., Feng, W., Xu, L. et al. Spatio-temporal rupture process of the 2008 great Wenchuan earthquake. Sci. China Ser. D-Earth Sci. 52, 145–154 (2009). https://doi.org/10.1007/s11430-008-0148-7
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DOI: https://doi.org/10.1007/s11430-008-0148-7