Listening for Diverse Signals From Emergent and Submarine Volcanoes

Underwater volcanoes produce seismic, tsunami, and volcanic hazards. Yet our first clues regarding underwater volcanism are often limited to observations from satellite imagery or regional seismic networks because of infrequent marine surveys and a limited number of seafloor observatories. On regional networks, large explosions and eruptions can be observed as well as volcanic tremor and magnitude >3 volcano-tectonic earthquakes and very-long-period events, albeit with limited resolution. However, at long distances, other types of signals such as long-period events, explosive-type signals, and landslides may go undetected. Thus there is a need to monitor underwater volcanism locally, to increase observations and enhance their quality and, consequently, sharpen our view of underwater volcanic processes. At present, local deployments of hydrophones and seismometers are rare for underwater volcanoes, perhaps because they seldom present a risk to communities. However, in the future, underwater volcano monitoring may shift toward using existing telecommunication cables. In this chapter, underwater volcano signals are discussed: how they are recorded, detected, monitored, and distinguished in underwater data in the context of known subaerial and submarine volcanism. Examples of known and monitored underwater volcanism are presented as well as economical and environment-friendly real-time submarine volcano monitoring options for the future.