Surface Wave Tomography via Higher-Order Interferometry

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

Although traditional ambient noise interferometry does not work for asynchronously deployed seismic stations, the method of higher-order interferometry provides one possible way to bridge stations that were not deployed simultaneously. For two asynchronous receivers, a backbone station that overlaps both in operation could serve as a virtual source (via noise interferometry). As a consequence, higher-order interferograms based on both direct and coda waves of the noise interferograms may reveal the seismic wavefields between two asynchronously deployed receivers. To analyze the characteristics of direct and coda wave interferometry empirically in both continental and oceanic settings, we use the EarthScope Tranportable Array (TA) and the Cascadia Initiative Array, respectively. Comparing coda wave with direct wave interferometry, our results indicate that the former can provide more new paths (nonexistent from standard ambient noise interferometry), while the latter requires fewer backbone stations to reach high quality records and may provide more reliable measurements at longer periods. The deployment of the TA in Alaska provides the unprecedented opportunity to image the lithospheric structure of Alaska. Higher-order interferometry can bridge numerous historical networks in Alaska and show promise to achieve enhanced resolution, broader bandwidth, and reduced uncertainties in tomographic maps and structural models. Furthermore, the enhancement in ray path coverage may prove to be an essential element for the study of azimuthal anisotropy. These conclusions may be significant for the design of future seismic array configurations in Alaska, in oceanic settings, and elsewhere.

Presenting Author: Michael Ritzwoller

Authors