IMAGING CRUSTAL STRUCTURE ALONG REFRACTION PROFILES USING MULTICOMPONENT RECORDINGS OF FIRST-ARRIVAL CODA

Abstract

In a way similar to receiver function imaging, coda of the first arrivals can be used to constrain crustal structure along controlled-source refraction profiles with multicomponent recording. Stacked cross-correlations of the radial and vertical components of recordings from three peaceful nuclear explosions of the 3850-km long profile QUARTZ (Russia) exhibit good correlation with the depth to the basement and provide a horizontal resolution level close to recording station spacing (10-15 km). The results also suggest high (∼0.35-0.4) average Poisson's ratios within the sediments. When applied to other multicomponent long-range refraction profiles, this approach could provide a simple and inexpensive way to constrain the structure of the upper crust that is required for interpretation of the deeper structures and that cannot be constrained by other means. Most importantly, reverberations within the sedimentary column apper to account for much of the observed complexity of the first-arrival waveforms, and therefore, such reverberations should be taken into account in the interpretations of seismic scattering from within the mantle.