Speaker
Description
In 2020, a temporary seismic experiment has been conducted by the CEA/DAM and the CNRS/LSBB with the support of more than 18 different academic laboratories or companies. During this experiment, the seismic wave field generated by several small active sources has been recorded in 3 dimensions on the site of the Laboratoire Souterrain Bas Bruit (LSBB), Rustrel, France. Taking advantage of the particular environment of the LSBB infrastructure (underground galleries, low seismic noise and a well-known geology), several kind of sensors have been installed at surface and in tunnels. The deployed instruments include about 100 SmartSolo seismometers from the DENSAR array - EOST, 200 DSU3- SERCEL accelerometers and more than 4km of optic cable for Distributed Acoustic Sensing (DAS) measurements with a FEBUS A1-R instrument. This 3D seismic data set provides opportunities to study the effect of the free surface (topography) and of local heterogeneities on the seismic wave field and its source signature. With a fiber total length of 10.5km, including loops and spools, several ground coupling conditions of the DAS fiber have been considered in order to evaluate the performance of this new seismic instrument in comparison to classical seismic sensors. After a detailed description of the experiment geometry and installed sensors, several examples of recorded signals and some preliminary analysis of this original data set will be presented.
