GA-OGS-ARSO Transfrontier CE3RN AdriaArray Seismicity Experiment (GOAT-CASE) installations and first results

GOAT-CASE experiment aims to evaluate the expected improvement in automatic earthquake localisation in the joint area of NE Italy, Austria and Slovenia, performed by respective authoritative agencies, also members of AdriaArray experiment and virtual network CE3RN. We re-picked P-wave arrival onsets on the seismometer channels of permanent seismic stations, additional AdriaArray stations and additional permanent stations in the joint area plus the 50 km surrounding belt. The onset detections were performed by each member of the experiment for stations within its authoritative area while the detection association was performed centrally. The resulting catalogue was compared against the joint catalogue of manually revised locations as the reference. Only the location parameters were compared in this experiment while the magnitudes were taken from manual catalogues. We used Antelope software for analysis in a similar way as in regular real-time monitoring procedures but with commonly agreed parameters. The comparison of procedures and parameters used by the three agencies was also one of the goals of the experiment. After reviewing the results of the comparison for the first two years of the experiment for events with local magnitude M > 1.5 we conclude that there is observable improvement in earthquake locations. This is reflected by the median distance between automatic and manual locations with the GOAT-CASE result being better than the results of any of the individual agencies. Additionally, we discuss the installation of six temporary stations by OGS in sites already used by the previously successful AlpArray project.