Abstract
On this picture we can see a Scintrex CG-5 relative gravimeter used to measure gravity in a natural underground site on the Larzac plateau. The CG-5 is a geodetic field instrument capable of measuring the difference in the gravity field between two points (measuring range up to 8000 mGal) at any point on the globe with a resolution of 10 nm/s² and a measurement repeatability of 50 nm/s². This instrument belongs to the mobile instrument park (Gmob) of the French Seismological and Geodetic Network managed by the CNRS-INSU. Résif is a national research infrastructure dedicated to the observation and understanding of the structure and dynamics of the Inner Earth. Résif is based on high-tech observation networks, composed of seismological, geodetic and gravimetric instruments deployed in a dense manner throughout France. The data collected make it possible to study with high spatial and temporal resolution the deformation of the ground, surface and deep structures, seismicity on a local and global scale and natural hazards, and more particularly seismic events, on French territory. Résif is part of the European (EPOS - European Plate Observing System) and global systems of instruments used to image the Earth's interior as a whole and to study many natural phenomena.