Mobile Earthquake Recording in Marine Areas by Independent Divers:New features-and Results from SPPIM, its First Big Deployment in the South Pacific
Abstract
Mermaid stands for Mobile Earthquake Recording in Marine Areas by Independent Divers. It is an autonomous freely-drifting underwater robot capable of recording acoustic conversions of earthquake signals while floating at a depth of 1.5 km, and rising to the surface to transmit such seismograms by satellite. Mermaid is already in use for seismic tomography. To image wave speed anomalies inside the Earth, seismologists use seismic waves, but the absence of recording stations in the oceans leads to poor ray coverage, which is now being remediated using Mermaid instruments. We have created a network called EarthScope-Oceans (ESO), an international collaboration (between France, China, US, and Japan). ESO recently launched 50 Mermaids in the South Pacific as part of the SPPIM (South Pacific Plume Imaging and Modeling)project. The instruments are expected to operate over five/six years, enough to image the superplume below Tahiti, providing unique seismic information where land stations or OBS are not available. The ability of MERMAIDS to drift gives the array a station density that is comparable to that of USArray. Since the deployment of some 50 units in the South Pacific in 2018-2019, Mermaid has been on a course towards multidisciplinary applications. Mermaid is now also capable of "landing" at the bottom of the oceans, e.g., for monitoring earthquake aftershocks. The advantage over, or complementarity with, OBH or OBS is that seismograms can be collected weekly to monitor the seismic activity of an area by having Mermaids rise to the surface to transmit detected event data. A one-year buffer memory allows for the recovery of virtually any other signal of interest. Mermaid is now also equipped with an EOM Seabird 41 is now also compatible with the Argo program. The present algorithm discriminates low-frequency signals for seismic tomography by detecting P-waves. A high-frequency prototype module, in addition to the existing configuration, is currently being tested in the Mediterranean Sea, to identify mammals, anthropogenic noise such as ship traffic, and meteorology.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMOS13B1520H
- Keywords:
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- 1222 Ocean monitoring with geodetic techniques;
- GEODESY AND GRAVITY;
- 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL;
- 4594 Instruments and techniques;
- OCEANOGRAPHY: PHYSICAL;
- 7299 General or miscellaneous;
- SEISMOLOGY