SEGJ Technical Conference

Comparison of the phase velocities in Soka, Saitama estimated from array strong-motion and microtremor records

Abstract We compared phase velocities obtained from microtremor array records with phase velocities obtained from strong-motion array records at the Soka array site. Using 7-element nested-triangular arrays of 1.0 km-50 m apertures, we measured the phase velocities from microtremor records with SPAC method. At the Soka array site, 7 strong-motion seismometers have been installed and have been recorded many earthquakes. We obtained phase velocities from the strong-motion array records during 2004 Niigata-ken Chuetsu and 2007 Niigata-ken Chuetsu-oki earthquakes applying f-k method. Comparing the phase velocities from the microtremor and strong-motion records with theoretically calculated phase velocities from a velocity structure model, it seems that the microtremor records consist of the fundamental mode of Rayleigh wave and that the phase velocities of the later phases of the strong-motion records correspond to the 2nd higher mode of Rayleigh wave.