Seismoacoustics in the South Pacific: Exploring the MERMAID Data Set and its Availability

Mobile Earthquake Recording in Marine Areas by Independent Divers (MERMAIDs) are drifting seismometers that record global seismicity from within the world's oceans. The platform was originally developed for the purpose of returning tomographically-useful ~1 Hz P-wave data sampling the lower mantle. In this presentation we show that the instrument has proven itself more capable than originally envisioned. The floats have recorded the seismoacoustic conversion P, S, and surface waves, as well as T phases, that traversed varied and novel ray paths sampling all depth ranges from the water column itself through to the Earth's core. Here we showcase the signals recording during the ongoing South Pacific Plume Imaging and Modeling (SPPIM) project, characterize their quality, compare them against similar signals recorded at island broadband and Raspberry Shake stations, quantify the data rate of return of the MERMAID instrument, and investigate the spatial pattern of their travel-time residuals. MERMAID data are now publicly available from the Incorporated Research Institutions for Seismology (IRIS) Data Management Center (DMC). Archival in the DMC presented unique challenges because MERMAIDs do not sit still like normal seismometers, and they record data below the sea surface and out of GPS range. These factors require that the location at the time of recording be interpolated from multiple surfacings, which we codify with new metadata standards for our moving instruments. Therefore, in this presentation we not only show and discuss the myriad seismoacoustic signals that MERMAID records, but we also introduce the new metadata distributed by IRIS alongside the MERMAID time-series so that others may finally include MERMAID data in their own research.