Crustal and upper mantle structure and the deep seismogenic environment in the source regions of the Lushan earthquake and the Wenchuan earthquake
Tóm tắt
Following the M
w7.9 Wenchuan earthquake, the M
w6.6 Lushan earthquake is another devastating earthquake that struck the Longmenshan Fault Zone (LFZ) and caused severe damages. In this study, we collected continuous broadband ambient noise seismic data and earthquake event data from Chinese provincial digital seismic network, and then utilized ambient noise tomography method and receiver function method to obtain high resolution shear wave velocity structure, crustal thickness, and Poisson ratio in the earthquake source region and its surroundings. Based on the tomography images and the receiver function results, we further analyzed the deep seismogenic environment of the LFZ and its neighborhood. We reveal three main findings: (1) There is big contrast of the shear wave velocities across the LFZ. (2) Both the Lushan earthquake and the Wenchuan earthquake occurred in the regions where crustal shear wave velocity and crustal thickness change dramatically. The rupture faults and the aftershock zones are also concentrated in the areas where the lateral gradients of crustal seismic wave speed and crustal thickness change significantly, and the focal depths of the earthquakes are concentrated in the transitional depths where shear wave velocities change dramatically from laterally uniform to laterally non-uniform. (3) The Wenchuan earthquake and its aftershocks occurred in low Poisson ratio region, while the Lushan earthquake sequences are located in high Poisson ratio zone. We proposed that the effect of the dramatic lateral variation of shear wave velocity, and the gravity potential energy differences caused by the big contrast in the topography and the crustal thickness across the LFZ may constitute the seismogenic environment for the strong earthquakes in the LFZ, and the Poisson ratio difference between the rocks in the south and north segments of the Longmenshan Fault zone may explain the 5 years delay of the occurrence of the Lushan earthquake than the Wenchuan earthquake.
Tài liệu tham khảo
Xie Z J, Jin B K, Zheng Y, et al. Source parameters inversion of the 2013 Lushan earthquake by combining teleseismic waveforms and local seismograms. Sci China Earth Sci, 2013, doi: 10.1007/s11430-013-4640-3
Liu C L, Zheng Y, Ge C, et al. Rupture Process of the M s7.0 Lushan Earthquake, 2013. Sci China Earth Sci, 2013, doi: 10.1007/s11430-013-4639-9
Zhang P Z, Xu X W, Wen X Z, et al. Slip rates and recurrence intervals of the Longmen Shan active fault zone, and tectonic implications for the mechanism of the May 12 Wenchuan earthquake, 2008, Sichuan, China (in Chinese). Chin J Geophys, 2008, 51: 1066–1073
Yin A, Harrison T M. Geological evolution of the Himalayan-Tibetan Orogen. Annu Rev Earth Planet Sci, 2000, 28: 211–280
Yi Z, Huang B, Chen J, et al. Paleomagnetism of early Paleogene marine sediments in southern Tibet, China: Implications to onset of the India-Asia collision and size of Greater India. Earth Planet Sci Lett, 2011, 309: 153–165
Wu Q J, Zeng R S, Zhao W J. The upper mantle structure of the Tibetan Plateau and its implication for the continent-continent collision. Sci China Ser D-Earth Sci, 2005, 48: 1158–1164
Wu Q J, Zeng R S. The Crustal structure of Qinghai-Xizang Plateau inferred from broadband teleseismic waveform (in Chinese). Chin J Geophys, 1998, 41: 669–679
Clark M K, Royden L H. Topographic ooze: Building the eastern margin of Tibet by lower crustal flow. Geology, 2000, 28: 703–706
Royden L H, Burchfiel B C, van der Hilst R D. The geological evolution of the Tibetan Plateau. Science, 2008, 321: 1054–1058
Zhang Z, Yuan X, Chen Y, et al. Seismic signature of the collision between the east Tibetan escape flow and the Sichuan Basin. Earth Planet Sci Lett, 2010, 292: 254–264
Zhang Z, Wang Y, Chen Y, et al. Crustal structure across Longmenshan fault belt from passive source seismic profiling. Geophys Res Lett, 2009, 36: L17310, doi: 10.1029/2009GL039580
England P, Molnar P. Active deformation of Asia: From kinematics to dynamics. Science, 1997, 278: 647–650
Rey P, Vanderhaeghe O, Teyssier C. Gravitational collapse of the continental crust: Definition, regimes and modes. Tectonophysics, 2001, 342: 435–449
Bendick R, Flesch L. Reconciling lithospheric deformation and lower crustal flow beneath central Tibet. Geology, 2007, 35: 895–898
Barmin M P, Ritzwoller M H, Levshin A L. A fast and reliable method for surface wave tomography. Pure Appl Geophy, 2001, 158: 1351–1375
Ghosh A, Holt W E, Flesch L M. Contribution of gravitational potential energy differences to the global stress field. Geophys J Int, 2009, 179: 787–812
Pascal C, Cloetingh S A P L. Gravitational potential stresses and stress field of passive continental margins: Insights from the south-Norway shelf. Earth Planet Sci Lett, 2009, 277: 464–473
Jones C H, Unruh J R, Sonder L J. The role of gravitational potential energy in active deformation in the southwestern United States. Nature, 1996, 381: 37–41
Ghosh A, Holt W E, Flesch L M, et al. Gravitational potential energy of the Tibetan Plateau and the forces driving the Indian plate. Geology, 2006, 34: 321–324
Hodges K V, Hurtado J M, Whipple K X. Southward extrusion of Tibetan crust and its effect on Himalayan tectonics. Tectonics, 2001, 20: 799–809
Naliboff J B, Lithgow-Bertelloni C, Ruff L J, et al. The effects of lithospheric thickness and density structure on Earth’s stress field. Geophys J Int, 2012, 188: 1–17
Zheng X F, Ouyang B, Zhang D N, et al. Technical system construction of Data Backup Centre for China Seismograph Network and the data support to researches on the Wenchuan earthquake (in Chinese). Chin J Geophys, 2009, 52: 1412–1217
Zheng X F, Yao Z X, Liang J H, et al. The role played and opportunities provided by IGP DMC of China National Seismic Network in Wenchuan earthquake disaster relief and researches. Bull Amer Meteorol Soc, 2010, 100: 2866–2872
Li Z W, Ni S D, Hao T Y, et al. Uppermost mantle structure of the eastern margin of the Tibetan plateau from interstation Pn traveltime difference tomography. Earth Planet Sci Lett, 2012, 335-336: 195–205
Li Z W, Xu Y, Huang R Q, et al. Crustal P-wave velocity structure of the Longmenshan region and its tectonic implications for the 2008 Wenchuan earthquake. Sci China Earth Sci, 2011, 54: 1386–1393
Xu Y, Li Z W, Huang R, et al. Seismic structure of the Longmen Shan region from S-wave tomography and its relationship with the Wenchuan M s8.0 earthquake on 12 May 2008, sourthwestern China. Geophys Res Lett, 2010, 37: L02304, doi: 10.1029/2009GL041835
Li C, van der Hilst R D, Toksöz M N. Constraining P-wave velocity variations in the upper mantle beneath Southeast Asia. Physics Earth Planet Int, 2006, 154: 180–195
Li C, van der Hilst R D, Engdahl E R, et al. A new global model for P wave speed variations in Earth’s mantle. Geochem Geophys Geosyst, 2008, 9: Q05018, doi: 10.1029/2007GC001806
Bai Z, Tian X, Tian Y. Upper mantle P-wave tomography across the Longmenshan fault belt from passive-source seismic observations along Aba-Longquanshan profile. J Asian Earth Sci, 2011, 40: 873–882
Liang C, Song X, Huang J. Tomographic inversion of Pn travel times in China. J Geophys Res, 2004, 109: B11304
Zhang P Z, Wen X, Shen Z K, et al. Oblique, high-angle, listric-reverse faulting and associated development of strain: The Wenchuan earthquake of May 12, 2008, Sichuan, China. Annu Rev Earth Planet Sci, 2010, 38: 353–382
Langston C A. Structure under Mount Rainier, Washington, inferred from teleseismic body waves. J Geophys Res, 1979, 84: 4749–4762
Zhu L, Kanamori H. Moho depth variation in southern California from teleseismic receiver functions. J Geophys Res, 2000, 105: 2969–2980
Ge C, Zheng Y, Xiong X. Study of crustal thickness and Poisson ratio of the North China Craton (in Chinese). Chin J Geophys, 2001, 54: 2538–2548
Sabra K G, Gerstoft P, Roux P, et al. Surface wave tomography from microseisms in Southern California. Geophys Res Lett, 2005, 32: L14311, doi: 10.1029/2005GL023155
Shapiro N M, Campillo M, Stehly L, et al. High-resolution surface-wave tomography from ambient seismic noise. Science, 2005, 307: 1615–1618
Yang Y, Ritzwoller M H, Zheng Y, et al. A synoptic view of the distribution and connectivity of the mid-crustal low velocity zone beneath Tibet. J Geophys Res, 2012, 117: B04303, doi: 10.1029/ 2011JB008810
Yang Y, Zheng Y, Chen J, et al. Rayleigh wave phase velocity maps of Tibet and the surrounding regions from ambient seismic noise tomography. Geochem Geophys Geosystem, 2010, 11: Q08010, doi:10.1029/2010GC003119
Zheng Y, Shen W, Zhou L, et al. Crust and uppermost mantle beneath the North China Craton, northeastern China, and the Sea of Japan from ambient noise tomography. J Geophys Res, 2011, 116,B12312, doi: 10.1029/2011JB008637
Zheng Y, Yang Y, Ritzwoller M H, et al. Crustal structure of the northeastern Tibetan plateau, the Ordos block and the Sichuan basin from ambient noise tomography. Earthquake Sci, 2010, 23: 465–476
Zhou L, Xie J, Shen W, et al. The structure of the crust and uppermost mantle beneath South China from ambient noise and earthquake tomography. Geophys J Int, 2012, 189: 1565–1583
Luo Y, Xu Y, Yang Y. Crustal structure beneath the Dabie orogenic belt from ambient noise tomography. Earth Planet Sci Lett, 2012, 313: 12–22
Yao H, Campman X, de Hoop M V, et al. Estimation of surface wave Green’s functions from correlation of direct waves, coda waves, and ambient noise in SE Tibet. Phys Earth Planet Int, 2009, 177: 1–11
Yao H, van der Hilst R D. Analysis of ambient noise energy distribution and phase velocity bias in ambient noise tomography, with application to SE Tibet. Geophys J Int, 2009, 179: 1113–1132
Yao H, Beghein C, van der Hilst R D. Surface wave array tomography in SE Tibet from ambient seismic noise and two-station analysis-II. Crustal and upper-mantle structure. Geophys J Int, 2008, 173: 205–219
Ligorría J P, Ammon C J. Iterative deconvolution and receiver-function estimation. Bull Seismol Soc Amer, 1999, 89: 1395–1400
Niu F, Li J. Component azimuths of the CEArray stations estimated from P-wave particle motion. Earthquake Sci, 2011, 24: 3–13
Sun Y, Toksöz M N. Crustal structure of China and surrounding regions from P wave traveltime tomography. J Geophys Res, 2006, 111: B03310, doi: 10.1029/2005JB003962
Sun Y, Li X, Kuleli S, et al. Adaptive moving window method for 3D P-velocity tomography and its application in China. Bull Seismol Soc Amer, 2004, 94: 740–746
Bensen G D, Ritzwoller M H, Barmin M P, et al. Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements. Geophys J Int, 2007, 169: 1239–1260
Lin F C, Moschetti M P, Ritzwoller M H. Surface wave tomography of the western United States from ambient seismic noise: Rayleigh and Love wave phase velocity maps. Geophys J Int, 2008, 173: 281–298
Zhang P Z, Deng Q D, Zhang G M, et al. Active tectonic blocks and strong earthquake in the continent of China. Sci China Ser D-Earth Sci, 2003, 46: 13–24
Shen W, Ritzwoller M H, Schulte-Pelkum V, et al. Joint inversion of surface wave dispersion and receiver functions: A Bayesian Monte-Carlo approach. Geophys J Int, 2013, 192: 807–836
Shen W, Ritzwoller M H, Schulte-Pelkum V. A 3-D model of the crust and uppermost mantle beneath the Central and Western US by joint inversion of receiver functions and surface wave dispersion. J Geophys Res, 2013, 118: 262–276
Christensen N I, Mooney W D. Seismic velocity structure and composition of the continental crust: A global view. J Geophys Res, 1995, 100: 9761–9788
Wang C Y, Han W B, Wu J P, et al. Crustal structure beneath the eastern margin of the Tibetan Plateau and its tectonic implications. J Geophys Res, 2007, 112: B07307, doi: 10.1029/2005JB003873
Wang C Y, Lou H, Lü Z Y, et al. S-wave crustal and upper mantle’s velocity structure in the eastern Tibetan Plateau—Deep environment of lower crustal flow. Sci China Ser D-Earth Sci, 2008, 51: 263–274
Wang Z, Fukao Y, Pei S. Structural control of rupturing of the Mw7.9 2008 Wenchuan Earthquake, China. Earth Planet Sci Lett, 2009, 279: 131–138
Lei J, Zhao D. Structural heterogeneity of the Longmenshan fault zone and the mechanism of the 2008 Wenchuan earthquake (M s8.0). Geochem Geophys Geosyst, 2009, 10: Q10010, doi: 10.1029/2009GC002590
Shan B, Xiong X, Zheng Y, et al. Stress changes on major faults caused by M w7.9 Wenchuan earthquake, May 12, 2008. Sci China Ser D-Earth Sci, 2009, 52: 593–601
Christensen N I. Poisson’s ratio and crustal seismology. J Geophys Res, 1996, 101: 3139–3156
Zhou Y S, He C R. The rheological structure of crust and mechanics of high-angle reverse fault slip for Wenchuan M s8.0 earthquake (in Chinese). Chinese J Geophys, 2009, 52: 474–484
Shan B, Xiong X, Zheng Y, et al. Stress changes on major faults caused by 2013 Lushan earthquake, and its relationship with 2008 Wenchuan earthquake. Sci China Earth Sci, 2013, doi: 10.1007/s11430-013-4642-1