Retrieval of Interstation Local Body Waves From Teleseismic Coda Correlations

We retrieve the local P wave empirical Green's functions between the elements of five different regional arrays across the globe by cross-correlating and bin stacking the teleseismic earthquake coda waves recorded at each array. The stack is made using the coda of P and S wave phases for events in the distance range from 40° to 50° from the center of the array. With a sequence of time windows along the coda the various body wave arrivals can be tracked, using record sections constructed by binning the stacked interstation correlograms in less than 1-km distance increments. The correlation of the coda part of each principal seismic phase produces highly coherent interstation arrivals for different analysis windows. Such arrivals can be reproduced by just stacking 100 arrivals from a pool of more than a thousand events, showing the stability of the observed Green's functions. Modeling for the structure beneath the Warramunga array in the Northern Territory, Australia, demonstrates that these arrivals correspond to multiply reflected arrivals from layers at different depths. The recovery of high-frequency interstation body waves from the teleseismic earthquake coda opens the prospect of conducting local high-resolution seismic imaging with teleseismic energy.