Progress Report NORSAR Phase 3

Abstract : The report covers the period 1 April - 30 June 1973 which is characterized by improving, estimating and simulating the array detection capability. The operational performance of the field equipment has been satisfactory also in this reporting period, and preventive maintenance has been emphasized. Much programming effort has been invested in automating the array monitoring analysis. The 978 seismic events reported in June are mainly due to two earthquake swarms from Japan and Kamchatka. Evaluation studies of NORSAR detection performance gave the best results for events in Central Asia and adjacent regions when the 90% cumulative detectability values are in the range 3.6-3.8 NORSAR m sub b units.