SHALLOW SHEAR WAVE VELOCITY FROM SEISMIC NOISE - ST. LOUIS

Seismic noise analysis is applied to sites in the St. Louis area to determine the shallow shear-wave velocity profiles, which are essential for estimation of seismic site response. The basis of this work is the technique developed by Aki (1957) which considers seismic noise as stationary waves in time and space and which estimates an apparent disperion curve. We use the recordings of seismic noise from two types of instruments, modern digital broadband and exploration, to be able to recover the apparent Rayleigh-wave dispersion over a wide range of periods. We explore the use of different data processing techniques to identify the one which provides a robust estimate of shallow velocity structure. The St. Louis area provides a good test bed for this evaluation because surficial material thicknesses range from a few meters to several 10's of meters.