Development of multi-channel opto-mechanical seismometers, with multi-kilometre fibres, for academic and industrial real-time applications.
Romain FERON defended his thesis on Wednesday 30 June before a jury comprising Matteo Barsuglia (Research Director Univ. of Paris – Laboratoire Astroparticule & Cosmologie, UMR CNRS 7164), Jean Chéry (Research Director Univ. de Montpellier – Géosciences Montpellier UMR CNRS 5243), Anne Deschamps (PR emeritus Laboratoire Géoazur – UMR CNRS 7329), Han Cheng Seat (MCF, HDR INP Toulouse – LAAS UPR CNRS 8001), Laurent Simon (Professeur Université du Mans – LAUM UMR CNRS 6613), Guy Plantier (Professor Groupe ESEO – LAUM UMR CNRS 6613), Pascal Bernard (Physicist CNAP IPGP – University of Paris) and Mathieu Feuilloy (Lecturer Groupe ESEO – LAUM UMR CNRS 6613).
Academic research and the monitoring of areas with high telluric hazards require the implementation of seismological instrumentation that may present certain limiting factors, both in terms of cost and ease of deployment.
For example, the severe environmental constraints inherent in certain geographical zones, such as volcanic edifices (temperature, acidity, lightning), deep boreholes or the seabed, do not always allow the installation of measurement equipment and real-time monitoring of active zones over the long term. The LINES project (ANR RiskNat – 2009-2012) has enabled the development of a fibre-optic displacement sensor applied to seismology.
This sensor, based on an extrinsic Fabry-Pérot interferometer, has made it possible to envisage the emergence of new seismometers that are more robust and less costly, while guaranteeing good metrological performance.
The work presented in this thesis is a continuation of this initial project. As part of the ANR HIPERSIS project (2017-2019), it aims to (i) propose a model of the optoelectronic measurement system, in order to assess its performance in terms of noise levels, linearity and bandwidth in particular, and the impact of environmental conditions on its behaviour; (ii) design, model and produce a geophone adapted to the optical measurement system, and in line with the expectations of the HIPERSIS project; and (iii) install and qualify the entire system at a site of interest: the Grande Soufrière in Guadeloupe.
An initial assessment of the contribution of this seismometer to the study of the volcano’s microseismicity will be drawn up.
The results of this study could encourage the network deployment of this type of sensor on other sites of interest – natural or industrial (geoindustries or civil engineering), as well as the diversification of mechanical structures associated with the optical interrogator (hydrophone, inclinometer).
