Analysis of asymmetric multipathing with a generalization of the double-beam method

Abstract

Abstract An array method integrating source and receiver array beamforming is presented. The method is a generalization of previous work (Krüger et al., 1993) to independent variation of slowness and azimuth in both the source and the receiver array. Compared to the analysis capabilities of a single array, the resolution is enhanced, and asymmetric scattering configurations and multipathing can be studied. The generalized double-beam method (DBM) is applied to a data set consisting of nuclear explosions detonated in Eastern Kazakhstan and recorded at the Yellowknife array in Northern Canada. The multipathing found for PcP and PdP is interpreted in terms of lateral inhomogeneity in the lowermost mantle below Severnaya Zemlya. Indications for Rayleigh-to-P-wave scattering observed for the Shagan River and Degelen subsites of the former main test site of the USSR in Eastern Kazakhstan can be related to the structure in the vicinity of the two subsites.