An extended MSPAC method in circular arrays

Elham Shabani (1) , Pierre-Yves Bard (2) , Noorbakhsh Mirzaei (1) , Morteza Eskandari-Ghadi (3) , Cecile Cornou (2) , Ebrahim Haghshenas (4)

1 Institute of Geophysics
2 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
3 Department of Engineering Science
4 Geotechnical Engineering Research Center

The microtremor seismic method using spatial autocorrelation (SPAC) processing is a useful tool for estimating the structure of subsurface layers and the shear wave velocities of sediments. This paper improves upon the well-known 'Modified SPAC' (MSPAC) method, which extends the SPAC formulae for discrete and nearly continuous circular arrays to handle arrays with regular and irregular azimuthal spacing. For finite circular arrays, extended MSPAC (EMSPAC) also takes into account the discrete character of the array, which has been inspired by the works of Okada. Also a new SPAC coefficient is proposed for a nearly continuous array. EMSPAC is applied to real data collected using a seven-station array, and its averaged SPAC coefficients and dispersion curves are compared to those obtained using MSPAC.

Mots clés: Spatial analysis; Surface waves and free oscillations; Site effects

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]; Milieux et Changements globaux

Elham Shabani, Pierre-Yves Bard, Noorbakhsh Mirzaei, Morteza Eskandari-Ghadi, Cecile Cornou, et al.. An extended MSPAC method in circular arrays. Geophysical Journal International, 2010, 182 (3), pp.1431-1437. ⟨10.1111/J.1365-246X.2010.04687.X⟩. ⟨insu-00565372⟩