Abstract Title: West Mata Submarine Volcano, NE Lau Basin: Eruption Evolution Using Hydroacoustic and Video Data

Abstract Submitted to: OCEAN SCIENCES

Abstract Text:

West Mata Volcano, near the Tonga Arc in the NE Lau Basin, is one of two submarine volcanoes that have simultaneous video and hydroacoustic record of its eruption. West Mata is the deepest eruption ever observed (~1,200 meters), and its behavior provides a window into prolonged eruptions in deep-ocean environments. In May 2009 the remote operated vehicle Jason collected video data and acoustic data with a portable hydrophone at the summit of West Mata. In December 2009, a moored hydrophone array was deployed to the north, east, south, and west of West Mata, each ~4 km from the summit. The north, east, and west stations were collected in April 2010, while the south station was redeployed and eventually recovered in August 2011. Since the video and portable hydrophone data were collected contemporaneously, these data can be correlated to better understand how different eruption styles appear in the acoustic record. The video data show that there is a range of eruption styles at West Mata, including active degassing with some lava fountaining to more explosive bubble bursting events. We use the moored hydrophone data to examine both short and long-term trends in eruption hydroacoustic behavior. With the range in eruption styles, there is clearly a range in eruptive signals that appear on spectrograms of the hydroacoustic data. For example, long duration broadband explosive sounds may indicate rapid degassing of the system, while, low frequency, impulsive, short duration signals lasting seconds to minutes may indicate successive bubble bursting events. These variations in the spectral content of the eruptive signals are distinct and can occur in rapid succession, over a few minutes, or change more gradually, over the course of months. A change in eruption styles may indicate variations in the magma rise rate, or a change in the gas flux of the system. Understanding how the different eruption styles at West Mata are represented in the hydroacoustic data may provide insights into other submarine volcanoes where eruptions cannot be directly observed, but hydroacoustic data is available.