Determination of 1-D Shear-Wave Velocity Profileusing the Refraction Microtremor Method

Summary In most urbanized areas estimating shallow shear-wave velocity profile for engineering assessments by using current commonly used technique are too expensive. In these sites to overcome ambient noises, large sources are required. But most of the times these sources are destructive and usually use of them are banned. Louie (2001) overcomes these problems by using refraction microtremor (ReMi). He used standard P-wave recording equipment and ambient noise to determine shear-wave velocity profiles down to 30m depths. The combination of commonly available equipments, simple recording with no source, a wave-field transformation data processing technique, and an interactive Rayleigh-wave dispersion modeling tool exploits the most effective aspects of the microtremor. In the presence of waves which are travelling at high apparent velocity, body waves, air waves and higher-mode Rayleigh waves by applying slowness-frequency wave-field transformation, we can pick Rayleigh-wave phase velocity dispersion curve accurately. In the south-west of Tehran land (Bordabad), we examine the application of this technique and determine shear-wave velocity up to 30m depths. Comparing this result with the result of geotechnical exploration shows the good correlation between them. This fact emphasizes the application of this technique in engineering assessments.