This study was initiated during an ATER (attach´e temporaire d’enseignement et de recherche) position funded by the University Paul Sabatier III (Toulouse, France) at the Institut de Recherche en Astrophysique et Plan´etologie (IRAP, UMR5277) part of the Observatoire Midi-Pyr´en´ees (OMP). This work was funded by EDF (Electricit´e de France) under the SIGMA (Seismic Ground Motion Assessment) project. This work was included in the work package 1 (WP1), The seismic source in hazard models. We acknowledge Kevin Manchuel, leader of WP1. We also acknowledge people involved in the TOPO-IBERIA and PYROPE projects for providing us with the high quality data from these temporary seismic deployments.We want also to acknowledge the institutions responsible for the maintenance of the different permanent seismic networks contributing data to this study: Instituto Geogr´afico Nacional of Spain (IGN), Catalonian Geological Institute (IGC), Commissariat `a l’Energie Atomique (CEA), French Broad-band network (RLBP) and RAP French strong motion network provided by RESIF - R´eseau Sismologique et g´eod´esique Franc¸ais.Seismic Network.doi:10.15778/RESIF.FR. RESIF is a national Research Infrastructure, recognised as such by the French Ministry of Higher Education and Research. RESIF is managed by the RESIF Consortium, composed of 18 Research Institutions and Universities in France. RESIF additionally supported by a public grant overseen by the French National Research Agency (ANR) as part of the ‘Investissements d’Avenir’ program (reference: ANR-11-EQPX- 0040) and the French Ministry of Ecology, Sustainable Development and Energy. We acknowledge Thomas Bardainne (CGG - Microseismic) and Mario Ruiz Fernandez (Institute of Earth Sciences Jaume Almera of the Spanish Scientific Research Council (ICTJA-CSIC)) for providing us access to traveltime picks and velocity models from temporary seismic experiments. We acknowledge Robert Sarda (IMERYS) for giving information about blasts at the Luzenac quarry. Thanks to Leo Zijerveld for his suggestions and help with the English. Authors thank Prof Egill Hauksson, editor and two anonymous reviewers for their constructive reviews and careful handling of the manuscript.

Local seismic networks are usually designed so that earthquakes are located inside them (primary azimuthal gap 180 degrees and distance to the first station higher than 15 km). Errors on velocity models and accuracy of absolute earthquake locations are assessed based on a reference data set made of active seismic, quarry blasts and passive temporary experiments. Solutions and uncertainties are estimated using the probabilistic approach of the NonLinLoc (NLLoc) software based on Equal Differential Time. Some updates have been added to NLLoc to better focus on the final solution (outlier exclusion, multiscale grid search, S-phases weighting). Errors in the probabilistic approach are defined to take into account errors on velocity models and on arrival times. The seismicity in the final 3-D catalogue is located with a horizontal uncertainty of about 2.0 +/- 1.9 km and a vertical uncertainty of about 3.0 +/- 2.0 km.

Peer reviewed