Document Type : Original Research Paper

Authors

University of Tehran, Institute of Geophysics, Tehran, Iran

Abstract

In this article, we studied the dynamic fracture process of Bam earthquake. In two presented models stress heterogeneity on the fault plain was modeled as barrier or asperity and friction included as slip-weakening relationship. Results of models were constrained by near field ground motion recorded in Bam station. In the first model, fracture starts form a weak asperity which its waves surround the neighbor barrier and break it down. In the second model, another asperity is included in southern part of the fault. Breaking barrier releases two fracture fronts traveling in two different regimes. One of them travels faster than shear waves and goes to the intersonic velocity. The other front travels with 0.74 shear wave velocity and makes the largest pulse of the record. Both models predict the slip rate successfully, but the second model is more consistent with the real data.

Keywords

 
References
Aki, K. & Richards, P. G., 1980- Quantitative seismology: Theory and methods, W. H. Freeman, San Francisco, 1: 56 p.
Andrews, D. J., 1976- Rupture velocity of plane strain shear cracks, J. Geophys. Res., 81: 5679-1976.
Archuleta, R. J., 1984 - A faulting model for the 1979 Imperial Valley earthquake, J. Geophys. Res., 89: 4559-4585.
Berberian, M., 2005- The 2003 bam urban earthquake: a predictable seismotectonic pattern along the western margin of the rigid Lut block, southern Iran, Earthquake Spectra, 21, S1: S35-S99.
Bouchon, M., Bouin, M., Karabulut, H., Toksoz, M. N., Dietrich, M. & Rosakis, A. J., 2001- Turkey earthquake, Geophys. Res. Lett., 27: 2723-2726.
Bouchon, M., Hatzfeld, D., Jackson, J. A. & Haghshenas, E., 2006- Some insight on why Bam (Iran) was destroyed by an earthquake of relatively moderate size, Geophys. Res. Lett., 33, L09309, doi: 10.1029/2006GL02596.
Bouchon, M., Tokosoz, N., Karabulut, H., Bouin, M. P., Dietrich, M. & Rosakis, A. J., 2000- Seismic imaging of the 1999 Izmit (Turkey) rupture inferred from the near-fault recordings, Geophys. Res. Lett., 27: 3013-3016.
Das, S. & Aki, K., 1977- A numerical study of two-dimensional spontaneous rupture propagation, Geophys. J. R. Astron. Soc., 50: 643-668.
Fu, B., Ninomiya, Y., Lei, X., Toda, S. & Awata, Y., 2004- Mapping active fault associated with the 2003 Mw 6.6 Bam (SE Iran) earthquake with ASTER 3D images, Rem. Sens. Envir., 92: 153-157.
Heaton, T. H., 1990- Evidence for an implications of self-healing pulses of slip in earthquake rupture, Phys. Earth Planet. Int., 64: 1-20.
Ida, Y., 1972- Cohesive force across tip of a longitudinal- shear crack and Griffith's specific surface energy, J. Geophys. Res., 77: 3796-3805.
Jafargandomi, J., Fatemi Aghda, M., Suzuki, S. & Nakamura, T., 2004- Strong ground motions of the 2003 Bam earthquake, southeast of Iran (Mw=6.5), Bull. Earthq. Res. Ins. 79: 47-57.
Madariaga, R. & Olsen, K.B., 2000- Criticality of rupture dynamics in 3-d, Pure Appl. Geophys., 157: 1981-2001.
Nakamura, T., Suzuki, S., Sadeghi, H., Fatemi Aghda, M., Matsushima, T., Ito, Y., Hosseini, K., Jafar Gandomi, A.  & Maleki, M., 2005- Source fault structure of the 2003 Bam earthquake, southeastern Iran, inferred from the aftershock distribution and its relation to the heavily damaged area: Existence of the Arg-e-Bam fault proposed, Geophys. Res. Lett., 32, L09308, doi: 1029/2005GL022631.
Page, M. T., Dunham, E. & Carlson, J. M., 2005- Distinguishing barriers and asperities in near-source ground motion, J. Geophys. Res., 110, B11302, doi: 10.1029/2005JB003736.
Palmer, A. C. & Rice, J. R., 1973- The growth of slip surfaces in the progressive failure of over-consolidated clay, Proc. R. Soc. London, Ser: A, 332: 527-548.
Spudich, P. & Cranswick, E., 1984- Direct observation of rupture propagation during the 1979 Imperial Valley earthquake using a short baseline accelerometer array, Bull. Seismol. Soc. Am., 74: 2083-2114.
Talebian, M., Fielding, E. J., Funning, G. J., Ghorashi, M., Jackson, J., Nazari, H., Pasons, B., Priestley, K., Rosen, P. A., Walker, R. & Wright, T. J., 2004- The 2003 Bam (Iran) earthquake – rupture of a blind strike slip fault, Geophys. Res. Lett., 31, xxxx,doi: 10.1029/20046GL020058.
Tatar, M., Hatzfeld, D., Moradi, A. S. & Paul, A., 2005- The 2003 December 26 Bam earthquake (Iran), Mw 6.6 aftershock sequence, Geophys. J. Int., 163, 90-105.
Wang, R., Xia, Y., Grosser, H., Wetzel, U., Kaufmann, H. & Zschau, J., 2004 - The 2003 Bam (SE Iran) earthquake: precise source parameters from satellite radar interferometry,  Geophys. J. Int., 10.1111/j .1365-246X.2004.02467x.