Direct estimation of rupture depths of earthquake faults from coseismic surface deformation
Tóm tắt
The rupture dimensions of earthquake faults are important parameters for characterizing earthquake ruptures and ground motions. Two key parameters to be determined are the rupture depth and dip angle of earthquake faults. Dislocation theory in an elastic half space indicates that if a seismic rupture directly runs up to the ground surface, there exist zero points of horizontal strain in the surface deformation, which correspond to the rupture depths, except for pure strike-slip faults. In this study, we use numerical simulations to investigate the possibility of inferring rupture depths from zero-strain points for cases of buried faults and heterogeneous media. The results show that the correspondence of zero-strain points to the rupture depths can be influenced by the heterogeneity of the underground media and the stress field. For buried faults, the correspondence relationship is approximately valid when the fault depth is <1 km. In addition, the range of earthquake fault dip angles can be estimated by horizontal displacements on the ground. We also study how to determine the rupture depths of faults from InSAR data after large earthquakes, and successfully apply the method to the 2008 Wenchuan earthquake. The method proposed here, which determines the parameters of fault geometry according to surface deformation, is simple and easy to perform. With independent of aftershocks, it can provide valuable constraints to kinematic inversions.
Tài liệu tham khảo
Alparone S, Gambino S. 2003. High precision locations of multiplets on south-eastern flank of Mt. Etna (Italy): Reconstruction of fault plane geometry. Phys Earth Planet Inter, 135: 281–289
Catchings R D, Gandhok G, Goldman M R, et al. 2008. Near-surface location, geometry, and velocities of the Santa Monica Fault Zone, Los Angeles, California. Bull Seismol Soc Amer, 98: 124–138
Cohen S C. 1996. Convenient formulas for determine dip-slip fault parameters from geophysical observables. Bull Seismol Soc Amer, 86: 1642–1644
Cohen S C. 1997. Erratum for “Convenient formulas for determine dip-slip fault parameters from geophysical observables” (vol 86, pg 1642, 1996). Bull Seismol Soc Amer, 87: 1081
Dziewonski A M, Anderson D L. 1981. Preliminary reference Earth model. Phys Earth Planet Inter, 25: 297–356
Fu B H, Shi P L, Guo H D, et al. 2011. Surface deformation related to the 2008 Wenchuan earthquake, and mountain building of the Longmen Shan, eastern Tibetan Plateau. J Asian Earth Sci, 40: 805–824
Fu Z, Hu C B, Zhang H M, et al. 2011. Possibility to infer rupture depths of fault earthquakes from zero-strain points of coseismic surface deformation. Seismol Res Lett, 82: 89–96
Hayes G P, Wald D J. 2009. Developing framework to constrain the geometry of the seismic rupture plane on subduction interfaces a priori—A probabilistic approach. Geophys J Int, 176: 951–964
Heermance R, Shipton Z K, Evans J P. 2003. Fault structure control on fault slip and ground motion during the 1999 rupture of the Chelungpu Fault, Taiwan. Bull Seismol Soc Amer, 93: 1034–1050
Hu C B, Zhou Y J, Cai Y E. 2009. Study of earthquake triggering in a heterogeneous crust using a new finite element model. Seismol Res Lett, 80: 799–807
Huang Y, Wu J P, Zhang T Z, et al. 2008. Relocation of the M8.0 Wenchuan earthquake and its aftershock sequence. Sci China Ser D-Earth Sci, 51: 1703–1711
Ide S, Takeo M, Yoshida Y. 1996. Source process of the 1995 Kobe earthquake: Determination of spatio-temporal slip distribution by Bayesian modeling. Bull Seismol Soc Amer, 83: 547–566
Johnson K M, Segall P. 2004. Imaging the ramp-decollement geometry of the Chelungpu fault using coseismic GPS displacements from the 1999 Chi-Chi, Taiwan earthquake. Tectonophysics, 378: 123–139
Lee J C, Chu H T, Angelier J, et al. 2002. Geometry and structure northern surface rupture of the 1999 M w=7.6 Chi-Chi earthquake: Influence inherited fold-belt structures. J Struct Geol, 24: 173–192
Li Y G. 2003. Characterization of failure zones at Landers and Hector Mine, California in 4-D by fault-zone guided waves. Earth Sci Front, 10: 479–505
Mansinha L, Smylie D E. 1971. Displacement fields of inclined faults. Bull Seismol Soc Amer, 61: 1433–1440
Massonnet D, Feigl K, Rossi M, et al. 1994. Radar interferometric mapping of deformation in the year after the Landers earthquake. Nature, 369: 227–230
Minshull T A, Hall B D. 1997. Geometry of a mid-ocean-ridge normal fault. Geology, 25: 835–838
Sekiguchi H, Irikura K, Iwata T. 2000. Fault geometry at the rupture termination of the 1995 Hyogo-ken Nanbu earthquake. Bull Seismol Soc Amer, 90: 177–133
Shin T C, Teng T L. 2001. An overview of the 1999 Chi-Chi, Taiwan, earthquake. Bull Seismol Soc Amer, 91: 895–913
Tan K, Qiao X J, Yang S, et al. 2011. Rupture characteristic and slip constrained by GPS coseismic deformation induced by the Wenchuan earthquake. Acta Geod Cart Sin, 40: 703–709
Tong X P, Sandwell D T, Fialko Y. 2010. Coseismic slip model of the 2008 Wenchuan earthquake derived from joint inversion of interferometric synthetic aperture radar, GPS, and field data. J Geophys Res, 115: B04314, doi: 10.1029/2009JB006625
Vos I M, Bierlein F P, Barlow M A, et al. 2006. Resolving the nature and geometry of major fault systems from geophysical and structural analysis: The Palmerville Fault in NE Queensland, Australia. J Struct Geol, 28: 2097–2108
Wang R J, Martin F L, Roth F. 2003. Computation of deformation induced by earthquakes in a multi-layered elastic crust—FORTRAN programs EDGRN/EDCMP. Comput Geosci, 29: 195–20
Wan Y G, Shen Z K, Wang M, et al. 2008. Coseismic slip distribution of the 2001 Kunlun mountain pass west earthquake constrained using GPS and InSAR data. Chin J Geophys, 51: 1074–1084
Xu X W, Wen X Z, Ye J Q, et al. 2008. The M s 8.0 Wenchuan earthquake surface ruptures and its seismogenic structure (in Chinese). Seismol Geol, 30: 597–629
Yu S B, Kuo L C, Hsu Y J, et al. 2001. Preseismic deformation and coseismic displacements associated with the 1999 Chi-Chi, Taiwan earthquake. Bull Seismol Soc Amer, 91: 995–1012
Zhang G H, Qu C Y, Song X G, et al. 2010. Slip distribution and source parameters inverted from co-seismic deformation derived by InSAR technology of Wenchuan M w7.9 earthquake (in Chinese). Chin J Geophys, 53: 269–279
Zhang P Z, Xu X W, Wen X Z, et al. 2008. 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, 51: 1066–1073
Zhang Y, Feng W P, Xu L S, et al. 2009. Spatio-temporal rupture process of the 2008 great Wenchuan earthquake. Sci China Ser D-Earth Sci, 52: 145–154
Zhang Z J, Xu T, Zhao B, et al. 2012. Systematic variations in seismic velocity and reflection in the crust of Cathaysia: New constraints on intraplate orogeny in the South China continent. Gondwana Res, 24: 902–917