Regional Seismic Threshold Monitoring
NORWEGIAN SEISMIC ARRAY (NORSAR) KJELLER
Pagination or Media Count:
A database comprising 45 seismic events, selected to provide the best possible ray path coverage of the Barents Sea and adjacent areas, has been compiled and reanalyzed. This has resulted in a mapping of the propagation efficiency of the different regional phases, new regional attenuation relations for Pn, Sn, Pg and Lg, together with a preferred average velocity model to be used for predicting the travel times of regional phases. We have applied these attenuation relations to develop and assess a regional threshold monitoring scheme for selected subregions of the European Arctic. Specifically, we have demonstrated how a number of small underwater explosions in the area following the kursk accident in the Barents Sea have been detected using the threshold monitoring technique. This first case study on regional threshold monitoring concerns the Novaya Zemlya region, and illustrates the performance of the method using different combinations of monitoring stations. The second case study focuses on the Kola Peninsula. This study gives us an impression of the potential TM performance in a case where a local network is available. For the most active mining areas in this region, the magnitude thresholds during normal noise conditions vary between 0.7 and 1.0 magnitude units.