Seismic monitoring in the oceans by autonomous floats.
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 M≥6.5. Even magnitudes <6.0 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.
UMR 6538 Domaines Océaniques, Université Européenne de Bretagne, Université de Bretagne Occidentale, CNRS, IUEM, 29280 Plouzané, France.
Alexey
A
Sukhovich
Géoazur, Université de Nice, UMR 7329, 06560 Valbonne, France.
Sébastien
S
Bonnieux
Géoazur, Université de Nice, UMR 7329, 06560 Valbonne, France.
Yann
http://orcid.org/0000-0002-2131-7299
Y
Hello
Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire d'Océanographie de Villefranche (LOV), 06230 Villefranche-sur-Mer, France.
Jean-Olivier
JO
Irisson
Department of Geosciences, Princeton University, Princeton, New Jersey 08544, USA.
Frederik J
FJ
Simons
Géoazur, Université de Nice, UMR 7329, 06560 Valbonne, France.
Guust
G
Nolet