Multicomponent Signal Processing for Rayleigh Wave Ellipticity Estimation: Application to Seismic Hazard Assessment

Dispersion curves of surface waves, i.e., the wave velocity as a function of frequency, are largely used in seismology to invert for the soil structure, i.e., the shear (and pressure) wave velocity profile as a function of depth. In addition to the dispersion curve, Rayleigh waves (one of the two most important types of seismic surface waves) exhibit a second property that is directly linked to the soil structure: ellipticity. This parameter indicates the ratio between the horizontal and vertical axes of the elliptical wave motion of Rayleigh waves and is also a function of frequency. Although some early applications of ellipticity measurements date back to the 1960s, it is only recently that this parameter has gained more attention, leading to the development of new methods allowing its estimation. These methods include single sensor and array vector-sensor processing techniques. The ellipticity can be inverted for the soil structure, an important property for the estimation of the seismic hazard at a given site. In this article, we will give an overview of the newly developed methods and compare their respective performances by analyzing simulated seismic signals.