Seismic monitoring in the oceans by autonomous floats

Alexey Sukhovich (1) , Sébastien Bonnieux (2) , Yann Hello (2) , Jean-Olivier Irisson (3) , Frederik J. Simons (4) , Guust Nolet (2)

1 LDO - Domaines Océaniques
2 GEOAZUR 7329 - Géoazur
3 LOV - Laboratoire d'océanographie de Villefranche
4 Princeton University

Our understanding of the internal dynamics of the Earth is largely based on images of seismic velocity variations in the mantle obtained with global tomography. However, our ability to image the mantle is severely hampered by a lack of seismic data collected in marine areas. Here we report observations made under different noise conditions (in the Mediterranean Sea, the Indian and Pacific Oceans) by a submarine floating seismograph, and show that such floats are able to fill the oceanic data gap. Depending on the ambient noise level, the floats can record between 35 and 63% of distant earthquakes with a moment magnitude MZ6.5. Even magnitudes o6.0 can be successfully observed under favourable noise conditions. The serendipitous recording of an earthquake swarm near the Indian Ocean triple junction enabled us to establish a threshold magnitude between 2.7 and 3.4 for local earthquakes in the noisiest of the three environments.

Domaines: Géophysique [physics.geo-ph]

Alexey Sukhovich, Sébastien Bonnieux, Yann Hello, Jean-Olivier Irisson, Frederik J. Simons, et al.. Seismic monitoring in the oceans by autonomous floats. Nature Communications, 2015, 6, pp.8027 ⟨10.1038/ncomms9027⟩. ⟨insu-01235776⟩