One-Dimensional Shear Wave Profiling for V30 and Nehrp Soil Classification Using the Refraction Microtremor (Remi) Method

The refraction microtremor (ReMi) method uses standard P-wave, refraction recording equipment to record ambient noise and then uses a wavefield transformation to produce Rayleigh wave dispersion curves from which average one-dimensional shear-wave profile of the subsurface can be derived. The combination of commonly available equipment, simple recording with no source, a wavefield transformation data processing technique, and an interactive Rayleigh-wave dispersion modeling tool exploits the most effective aspects of the microtremor, spectral analysis of surface wave (SASW), and multichannel analysis of surface wave (MASW) techniques. It overcomes several of the problems afflicting other techniques for estimating shallow shear velocities that make them expensive or difficult to use in urban areas. For example, the refraction microtremor method requires no source, no drilling, and noise helps rather than hinder the data acquisition. It has been very effective for quickly and cheaply determining 30-m average shear wave-velocity (V30) and thus the NEHRP (National Earthquake Hazard Reduction Program) soil classification. In addition, it has also been used for liquefaction analysis and finding buried cultural features, such as dumps and piers. In this paper we briefly discuss the method and present case studies showing its use in different geologic settings and engineering applications