Specific action: Rap Permanent accelerometer network

Outlines

The French Permanent Accelerometer Network (Rap) is part of the Seismology thematic group. Its aim is to improve knowledge of the strong ground motions and building movements that could be caused by earthquakes in France. Since 1997, the Rap has been acquiring, disseminating and promoting accelerometric data from earthquakes recorded in mainland France and overseas, with the help of regional networks that maintain accelerometric stations in the field (158 stations by 2022).

Objectives

The Rap has installed its stations in regions with relatively high seismicity, where the risk is the highest (Antilles, Alps, Provence and Pyrenees), but also in regions where seismicity is more modest but not negligible (Rhine Graben, Ardennes, Central Massif, Armorican Massif, Mayotte). One of the challenges is to install the stations as close as possible to the seismic sources in order to record the strong motion over a short distance (ideally less than 20 km). The deployment and development of the network are therefore heavily dependent on advances in our knowledge of seismicity in France and potentially active faults. The Rap also aims to install its stations in locations that are sensitive to seismic risk: specific geological sites where seismic waves are expected to be amplified, and urban areas with high human, economic or environmental stakes.

The main scientific objective is to improve our understanding of the physical mechanisms involved in the generation of strong and destructive seismic events.

The scientific objectives of the Rap Specific Action are therefore to:

• understanding rupture processes on faults (seismic source effects) ;
• analysis and prediction of ground motion in frequencies relevant to civil engineering;
• understanding the local amplification of seismic waves by geology (site effects);
• experimental measurement of the response of buildings and the urban environment to seismic stress;
• non-linear dynamics of structures and vulnerability.