A MERMAID Miscellany: Seismoacoustic Signals beyond the <i>P</i> Wave

Abstract Mobile Earthquake Recorder in Marine Areas by Independent Divers (MERMAID) is a passively drifting oceanic diving float that transmits acoustic pressure records from global earthquakes within hours or days of their rupture. The onboard algorithm used for the detection and identification signals hydrophone prioritizes recovery ∼1 Hz teleseismic P waves, which are useful seismic imaging Earth’s mantle. Two years into mission launched 50 MERMAIDs to map 3D mantle wavespeed anomalies with high resolution under Pacific French Polynesia, it clear data returned contain much information beyond first-arriving phases. These include conversions S surface T inner- outer-core phases, generated heard across globe—and sounds otherwise unidentified events occurring remote uninstrumented parts world’s oceans. Our growing database automatically accumulating ∼240 s long-triggered segments contains treasure trove geophysicists interested seismology P-wave tomography. Furthermore, equipped two-way communication capabilities, MERMAID can entertain requests deliver its 1 yr buffer. In this article, we highlight classes categories MERMAID’s “extended-utility” catalog.