Optical long range instruments for high resolution monitoring of geohazard in harsh environment

Description

In many areas with high telluric hazard, our understanding of the seismogenic and mechanical processes is limited by the difficulty or impossibility to deploy arrays of high performance seismometers or of other geophsyical sensors, due to high cost and/or difficulty of the installation and maintenance. This led us to develope several optical instruments: the idea was to separate, by a long optical fiber, the robust mechanical part of the sensor from the opto-electronic part, which interrogates the sensor and measures its internal deformation with Fabry-Perot (FP) interferometry. Our IPGP-ESEO team has thus constructed innovative optical seismometers and strainmeters, complemented by borehole and long base optical tiltmeters from Geoscience Montpellier and ENS. Here we present the ESEO-IPGP instruments, and their successful installation in the field: one seismometer at the top of La Soufrière volcano (1.5 km long fiber), 10/2019 (ANR HIPERSIS ); one ocean-bottom seismometer offshore Les Saintes, 06/2021 (FIBROSAINTES, Interreg Caraïbe PREST) (5 km long fiber buried by a plow GEOAZUR); and one strainmeter on the Stromboli volcano (09/2021).

Abstract

International audience

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