On the Formation of Global Inter‐Source Correlations and Applications to Constrain the Interiors of the Earth and Other Terrestrial Planets

Abstract

The cross‐correlation stack of earthquake late‐coda between seismic receivers on a global scale – global inter‐receiver correlogram – exhibits numerous features that provide information on the Earth's structure. The cross‐correlation stack between seismic sources (global inter‐source correlogram) can also be constructed, and, in theory, it should reproduce the correlation features seen in the inter‐receiver correlogram. However, practical attempts at global inter‐source correlograms have not produced the theoretical expectations. Namely, the obtained inter‐source correlograms are void of discernable correlation features. Here, we address this problem and document the steps that have to be undertaken to produce the inter‐source global correlogram with the equivalent abundance of correlation features. We show that forming inter‐source correlation features requires constructive contributions determined by specific source mechanisms and source‐receiver geometries. They are overwhelmed by destructive contributions if seismic records of all available sources and source‐receiver geometries are used. Building upon that, we present an effective procedure for constructing global inter‐source correlations through a rigorous selection of source mechanisms and source‐receiver geometries. The resulting inter‐source correlations exhibit numerous prominent correlation features as predicted. Notably, this method enables the construction of global inter‐source correlations in a special case with a single seismic receiver. Furthermore, we explore and demonstrate the feasibility of utilizing single‐receiver inter‐source correlations to constrain the interiors of the Earth and other terrestrial bodies. Our study facilitates practical applications of global inter‐source correlations, providing additional constraints on the Earth's structure and offering an effective routine to probe the interiors of other planets and moons using currently affordable resources.