Interpreting the dynamics of submarine landslides through hydroacoustic modeling, West Mata volcano, NE Lau Basin

Landslides are an integral process in the development of submarine volcanoes, but these events are rarely recorded and observed. Therefore, understanding how the morphology of volcanoes evolve requires information on landslides. Hydroacoustic signals were analyzed for the purposes of characterizing frequent landslides on West Mata volcano during a 5-month eruptive period. Over 200 landslide signals have been compared in conjunction with hydroacoustic modeling to better understand the dynamics that control them. We used interference patterns produced by multipath rays to identify and model these slope failures. Landslides were most clearly captured on the north and west stations, suggesting a source on the western face of West Mata. This is consistent with a zone of high sediment accumulation previously found by bathymetric depth difference mapping. Landslides were found to initiate ~200-300 m below the summit and travel at speeds of 4-8 m/s, and possibly up to 20 m/s. Slope failures were observed during periods of high eruptive activity suggesting failure by unstable tephra loading preferentially at sites of previous sliding. Landslides at West Mata also tend to occur in clusters with decreasing run out distances over time. It is recommended that future studies involve a denser hydrophone network to better locate landslides and model slide mechanics