Excitation of the global correlation wavefield by large earthquakes

Abstract

Recorded globally, cross-correlated ground-motion time-series of the coda of large earthquakes enable the construction of a 2-D representation of correlation lapse time and inter-receiver distance—a global correlogram. A better understanding of how the features present in a correlogram are generated can revolutionize the characterization of planetary interiors. Here, we investigated correlograms based on individual large earthquakes and identified 12 events from the past decade with a multitude of prominent and some ‘exotic’ features in the first 3 hr following correlation origin. We found that the type of the source mechanism and energy-release dynamics are the key influencers responsible for individual correlograms equal in quality to a stack of hundreds of correlograms. A single event is sufficient in creating a correlogram resembling previous correlograms constructed from a large number of events, which reinforces the notion that the earthquake coda-correlation features are not ‘reconstructed’ body waves. Numerical simulations of the correlation wavefield can thus be based on exceptionalquality events, becoming more computationally affordable. Here, we explain more than 60 features of the global coda-correlogram, which presents the most extensive catalogue to date Show more