Successful installation of the first connected underwater observatory in Guadeloupe

This first recording marks the success of several years’ research and development on fibre-tip optical sensors, carried out by the IPGP, ESEO and ENS as part of the Interreg PREST project, with a view to closely monitoring the seismicity of the Saintes area, which was hit in 2004 by a magnitude 6.3 earthquake, the largest to hit the French West Indies for decades, and whose persistence is still debated.

Installed for the first time in real monitoring conditions, this innovative seismological station overcomes many of the problems associated with the usual deployment of electronics and energy on the seabed. The seismometer, which is purely mechanical, is installed at a depth of 40 m underwater and connected to land by a 5 km long optical cable, at the end of which a laser interrogator allows its movement to be measured remotely with a high degree of accuracy. This data is now transmitted in real time to the IPGP’s volcanological and seismological observatories in Guadeloupe and Martinique. In addition, thanks to an innovative approach to monitoring light signal disturbances linked to the passage of seismic waves, the fibre itself serves as a network of sensors (the equivalent of 500 seismometers!). This DAS (Distibuted Acoustic Sensing) method was set up as part of a PREST-Géoazur collaboration.