Crustal Structure of the Macquarie Ridge Complex Constrained by the Ambient Noise and Earthquake Autocorrelograms

The Macquarie Ridge Complex (MRC) constitutes the boundary between the Indo-Australian and Pacific plates in the southwest Pacific Ocean. It accommodates the world’s most potent sub-marine earthquakes that are not associated with ongoing subduction. To better understand the nature of MRC and its associated earthquakes, we aim to explore the crustal structures using recordings from island-based stations and ocean bottom seismometers (OBS). In particular, these OBSs, which are deployed in the surroundings of Macquarie Island from October 2020 to November 2021, enable us to image the refined oceanic structures beneath the study area. In this study, we obtain the body-wave reflections by computing phase coherence autocorrelations of both ambient noise and earthquake data. Our preliminary reflection profiles by both methods reveal coherent reflected P waves that may be related to Moho and additional structures within the crust and upper mantle.