Hydroacoustic measurements of the 2004 submarine eruption near Nightingale Island, Tristan da Cunha

Little is known about active volcanism in the remote regions of the global ocean. Here, we resort to long‐range acoustic measurements to study the July/August 2004 eruption at Isolde, a submarine volcanic cone in the Tristan da Cunha archipelago, South Atlantic Ocean. Underwater sound phases associated with the event were recorded as far as Cape Leeuwin, Western Australia, where a bottom-moored hydrophone array is operated as part of the International Monitoring System (IMS). IMS hydrophone data in combination with local seismic observations suggest that the center of activity is located east of Nightingale Island, where a recent seafloor mapping campaign aboard R/V Maria S Merian (MSM20/2) has revealed a previously unknown, potentially newly formed stratocone. Transmission loss modeling via the parabolic equation approach indicates that low-frequency sound phases travel at shallow depths near and within the Antarctic Circumpolar Current, thereby avoiding bathymetric interference along the 10,265 km source-receiver path. Our study highlights the potential of the IMS network for the detection and study of future eruptions both at Isolde and elsewhere. Implications for test-ban treaty monitoring and volcano early warning will be discussed.