Probabilistic ambient noise imaging of the Macquarie Ridge Complex using ocean-bottom and land-based seismometers

The Macquarie Ridge Complex, located at the boundary between Indo-Australian and Pacific plates in the southwest Pacific Ocean, hosts some of the largest submarine earthquakes of the 20th and 21st centuries, not associated with ongoing subduction. To understand the origin of the sub-marine earthquakes and their potential earthquake and tsunami hazards to Australia and New Zealand, we installed 27 ocean-bottom seismometers and five land-based seismometers on Macquarie Island. This study will employ state-of-the-art processing methods to analyze this unique seismic dataset from the 20 recovered seismic stations to image the tectonic settings beneath the MRC. As the main result, we present a preliminary tomographic model and its relevant uncertainty estimate of the region constructed from ambient noise surface waves using a probabilistic inversion framework. The tomograms will be complemented with receiver-based imaging results such as P-wave coda autocorrelations and receiver functions to confirm the existence of lithospheric features. The results are expected to advance an ongoing understanding of the tectonic settings under the MRC and unpuzzle the origin of the significant underwater earthquakes that occur in the area.