2025_programme: Monitoring underwater eruptions using networks of hydrophones in the SOFAR channel

• Day: June 16, Monday
    Location / Time: A. TERPSIHORI at 11:40-12:00
• Last minutes changes: -
• Session: 04. Comprehensive Nuclear-Test-Ban Treaty Monitoring, and its Civil and Scientific Applications
  Organiser(s): Georgios Haralabus, Mario Zampolli, Tiago Oliveira, Mark Prior
  Chairperson(s): Georgios Haralabus, Tiago Oliveira
• Lecture: Monitoring underwater eruptions using networks of hydrophones in the SOFAR channel
  Paper ID: 2160
  Author(s): Sara Bazin, Pierre-Yves Raumer, Aude Lavayssière, Hugo Fauvel, Romain Safran, Vaibhav Vijay Ingale, Jonathan Tanrin, Julien Vergoz, Jean-Yves Royer, Jun Korenaga
  Presenter: Sara Bazin
  Abstract: Most volcanic eruptions occurring in the ocean remain undetected. Hydroacoustic monitoring, a widely used method among seismologists due to its sensitivity to T-phases associated with the low-level seismic activity in remote oceanic regions, can address this knowledge gap. Indeed, near volcanic areas, such as spreading ridges or undersea volcanoes, acoustic data recorded by moored hydrophones display numerous impulsive signals of short durations (5-15 s) and high energy (up to 100 Hz), that we attribute to interactions between hot lava and cold seawater. Most likely, thermal cracking is the process that generates these signals, which can be used as proxies to detect and locate new lava flows. These impulsive events were found in three different networks located in the Indian Ocean: (i) the large-scale OHA-SISBIO network, composed of 6-9 autonomous hydrophones encompassing 1000-km-long sections of the three Indian mid-oceanic ridges; (ii) the small-scale MAHY network, with 4 autonomous hydrophones 50 km away from a new-born volcano off Mayotte Island, Mozambique Channel; and (iii) the hydroacoustic stations of the International Monitoring System, consisting of cabled-to-shore triplets of hydrophones. In all these areas and data, we identified clusters of impulsive events, within clusters of seismic events, related to volcanic activity. To further optimize eruption monitoring, we developed automatic AI-based detection, classification and localisation tools. Implementing such automatic detection of volcanic events in real-time hydrophones, as the IMS stations, would be a major advance for organizing in-situ studies of active submarine volcanoes. When real-time stations are not available, we deployed innovative autonomous hydrophones equipped with small messengers to enable data retrieval from a small vessel of opportunity, should a major cluster of events occur in a monitored area.
    Download the full paper
• Corresponding author: Dr Sara Bazin
  Affiliation: Geo-Ocean/IUEM/UBO
  Country: France