Green’s function retrieval from deterministic seismic wavefield using higher-order cross-correlation

Summary

Seismic interferometry, commonly known as empirical Green’s function retrieval in seismology, has been widely applied to extract the impulse response of Earth. The conventional approach based on cross-correlation of long-term ambient seismic wavefield relies on the simultaneous recording of noise signals at seismic receivers. Recent studies have demonstrated observationally that the correlation of coda of (ambient noise) cross-correlation function (C³) enables the reconstruction of inter-station Green’s function regardless of the operating time (i.e., synchronous or asynchronous) of stations. Here we extend the C³ scheme to a more general framework that involves the correlation of cross-correlation function (C²). This new approach exploits the deterministic energy of the wavefield and is more robust than C³ that may suffer from incoherent coda wave energy due to less ideal (e.g., sparse, noisy, short duration) network configurations. We apply this technique to the recently deployed ALFREX seismic network in southwestern Australia. We show that the Green’s function between asynchronous stations can be robustly recovered using the C² approach whereas this is not feasible from C³. The proposed technique can effectively bridge the temporal gaps between temporary networks and demonstrate great potential for improving the spatial coverage of data and resolution in seismic imaging of crustal structures.

• Seismic interferometry
• deterministic wavefield
• ambient noise cross-correlation
• Green’s function
• seismic imaging
• Australian crust