Document Type : Original Research Paper


1 International Institute of Earthquake Engineering and Seismology, Tehran, Iran

2 Institute of Geophysics, University of Tehran, Tehran, Iran Seismotectonic Department, Geological Survey of Iran, Tehran, Iran


The shear wave velocity structure in Bam city is estimated in this paper. A double circle array observation of microtremors was conducted in south-east of Bam. Spatial Auto-correlation Coefficient (SPAC) method was utilized to determine phase velocity dispersion curve of Rayleigh wave in frequency range from 1.6 to 2.3 Hz. An inversion scheme based on Genetic Algorithm was employed to estimate the VS profile up to 400 m at the site under study. The inverted shear wave velocities are compared with the available down-hole data, and are found to be in good agreement. It verified the reliability of the estimated shear wave velocity profile and confirmed the use of SPAC method as a good alternative to the conventional approaches due to relatively low costs, ease of operation and analysis, accuracy, and ability to explore soil profile up to large depth.


Aki, K., 1957- Space and time spectra of stationary stochastic waves with special reference to microtremors. Bulletin of the Earthquake Research Institute, University of Tokyo, 35, 415-457.
Apostolidis, P., Raptakis, D., Roumelioti, Z., Pitilakis, K., 2004- Determination of S-wave velocity structure using microtremors and spac method applied in Thessalonoki (Greece). Soil Dynamic and Earthquake Engineering, 24, 49-67.
Ghayamghamian, M. R. & Hisada, Y., 2007- Near-fault strong motion complexity of 2003 Bam earthquake (Iran) and low-frequency ground motion simulation. Geophysical Journal International, 170: 679-686.
Konagai, K., Yoshimi, M., Meguro, K., Yushimura, M., Mayorka, P., Takashima, M., Farahani, A., Tahghighi, H., Keshavarz., M.,2003- Strain Induced in cracked utility poles and damage to dwelling from the Dec 26, 2003- Bam earthquake, Bulletin of the Earthquake Research Institute, University of Tokyo, 79: 59-67.
Kudo, K., Kanno, T., Okada, H., Özel, O., Erdik, M., Sasatani, T., Higashi, S., Takahashi, M. and Yoshida, K., 2002- Site-specific issues for strong ground motions during the Kocaeli, Turkey, earthquake of 17 August 1999, as inferred from array observations of microtremors and aftershocks, Bulletin of the Seismological Society of America, 92: 448-465.
Okada, H., 2003- The Microtremor Survey Method (translated by Koya Suto), Geophysical Monograph Series, No. 12, Society of Exploration Geophysicists, p.135.
Roberts, J. C., Asten, W. A., 2004- Resolving a velocity inversion at the geotechnical scale using the microtremor (passive seismic) survey method, Exploration Geophysics, 35: 14-18.
Suzuki, S., Fatemi Aghda, S. F., Nakamura, T., Matsushima, T., Yoshihiro, I., Sadeghi, H., Maleki, M., Jafar Gandomi, A., Hosseini, S. H., 2004- Temporal seismic observation and preliminary hypocenter determination of aftershocks of the 2003 Bam earthquake, southeastern Iran, Bulletin of the Earthquake Research Institute, University of Tokyo, 79: 37-45.
Talebian, M., Fielding, E.J., Funning, G.J., Ghorashi, M., Jackson, J., Nazari, H., Parsons, B., Priestley, K., Rosen, P.A., Walker, R., & Wright, T.,2003- The 2003 Bam (Iran) earthquake: rupture of a blind strike-slip fault, Geophysical Research Letters, 31, L11611, doi:10.1029/2004GL020058.
Towhata, I., Ghalandarzadeh, A., Shahnazari, H., Mohajeri, M. & Shafiee, A.,2003- Seismic behavior of local soil and foundation in Bam City the 2003 Bam earthquake in Iran, , Bulletin of the Earthquake Research Institute, University of Tokyo, 79: 69-80.  
Tatar, M., Hatzfeld, D., Moradi, A. S., & Paul, A., 2005- The 2003 December 26 Bam earthquake (Iran), Mw 6.6, aftershock sequence, Geophysical Journal International, 163:90-105.
Yamanaka, H. and Ishida, H., 1996- Application of genetic algorithm to an inversion of surface wave dispersion data, Bulletin of the Seismological Society of America, 86: 436-444.
Walker, R. & Jackson, J., 2004- Active tectonics and late Cenozoic strain distribution in central and eastern Iran. Tectonics, 23, TC5010, doi:10.1029/2003TC001529