HYDROMOMAR20

Type Oceanographic cruise
Set This cruise is part of the set HYDROMOMAR
Ship Thalassa
Ship owner Ifremer
Dates 28/08/2020 - 18/09/2020
Chief scientist(s) PERROT Julie

GEO-OCEAN - UMR 6538

IFREMER - Technopôle Brest-Iroise

IUEM - Rue Dumont d'Urville

29280 Plouzané

https://www.geo-ocean.fr/

DOI 10.17600/18000655
Objective

The scientific goal of the HYDROMOMAR20 survey is the study of the accretionnary processes at the axis of a slow ridge, in a context where this ridge interacts with a hot spot, that of the Azores. The observation and location of the small-magnitude earthquakes occurring along accreting ocean boundaries provides insight into the various geodynamic, magmatic, tectonic, hydrothermal, ... processes that occur along these boundaries. However, these processes, generating earthquakes of magnitude mostly less than 5, represent barely 1% of earthquakes detected by global terrestrial seismic networks in the EMSO-Açores zone. In addition, the seismicity observed at  a ridge has a low occurrence rate of more than 5 years. Therefore, the deployment of autonomous hydrophone networks in the SOFAR channel is necessary to study the active processes along the oceanic ridges, that is to say, record for several hundreds of kilometers of earthquakes  with small magnitudes (M<4) and with a seismic cycle high (1 occurrence every 5 years). Five hydrophones deployed in the area south of the Azores from 25 June to 7 July 2018  have  been recovered in september 2020.

Figure: the locations of the hydrophone are represented by a yellow star. The black circles represent the location of the seismicity recorded by the first catalogue HYDROMOMAR-1, -2 and -3  from june 2010 to june 2016, and the black lines, the N/O Thalassa routes.

Data managed by SISMER