Permanent seismological observation on the metropolitan territory began more than 100 years ago with the creation of the Strasbourg seismological station in the gardens of the Kaiser-Wilhelms-Universität. In the early 1980s, the forty or so academic seismological stations, managed by various regional observatories, were federated within the National Seismic Monitoring Network (RéNaSS), whose management was entrusted to the IPGS. This network, composed of short-term sensors dedicated to the analysis of local seismicity, counted more than a hundred stations in the 1990s, but with a very heterogeneous distribution and highly variable technical characteristics depending on the region. At the beginning of the 2000s, the democratization of high-bandwidth and high-dynamic sensors, allowing a greater variety of analyses, led the French seismological community to propose the realization of a true “broadband” metropolitan network, following the example of those developed worldwide (including the Geoscope network) and in other European countries. The Permanent Broadband Network (RLBP) was officially labeled as a CNRS-INSU National Observation Service in 2007. It involves eight Observatories of the Sciences of the Universe (OSU) as well as the Department of Analysis, Monitoring, Environment (DASE) of the CEA, and is coordinated by Eost.

The need to develop the RLBP was partly at the origin of the setting up of the Résif Research Infrastructure, of which it is now a specific action. The extension of the RLBP is mainly financed via the EquipEx Résif-Core, selected during the second wave of the Plan des Investissements d’Avenir (Future Investment Plan) in 2011 and which should be extended until the end of 2020.

Consisting of 17 stations at its creation, the RLBP’s ambition is to build by 2022 a network of about 190 stations covering the whole territory, but with an increased density in the most seismic areas. This density of stations will significantly improve our knowledge of the deep structure, as well as our estimation of the seismic hazard in France, by lowering the magnitude of completeness to less than 2 over the whole territory.

The aim is also to be able to use this network as a real seismological antenna for long periods, in particular through its integration into the European virtual network of the EPOS infrastructure. In addition, the RLBP aims to provide data of very high quality. This implies choosing isolated sites, to limit seismic noise generated by human activity, and careful installation of seismometers to attenuate the influence of environmental parameters (temperature, pressure, wind). It also involves putting in place various tools and procedures to provide the most complete time series possible and correct and continuously updated metadata (May 2019). The French Seismological and Geodetic Network Résif is a national research infrastructure dedicated to the observation and understanding of the Earth’s internal structure and dynamics. Résif is based on observation networks of high technological level, composed of seismological, geodetic and gravimetric instruments densely deployed throughout the French territory. The data collected allow to study with a high spatio-temporal resolution the ground deformation, the superficial and deep structures, the seismicity at the local and global scale and the natural hazards, and more particularly seismic, on the French territory. Résif is part of the European (EPOS – European plate observatory system) and worldwide systems of instruments used to image the Earth’s interior as a whole and to study numerous natural phenomena.

To find out more about the RLBP, visit the RLBP website

Download the Eost Newsletter n°32, June 2019 (pdf in French).

Drilling of the Fourg RLBP station in the summer of 2018 by a team from Eost and BRGM © Jérôme Vergne, Eost. To know more about it.