[MAG40-P03] CTBT IMS hydroacoustic signal detections from the Ioto volcanic island in the northwest Pacific Ocean
Keywords:Internataional Monitoring System (IMS), Hydrophone triplet, Ioto
During the same period, a large number of underwater acoustic (hydroacoustic) signals were recorded by the Comprehensive Nuclear-Test-Ban Treaty’s (CTBT) International Monitoring System (IMS) hydroacoustic (HA) station HA11 Wake Island. A set of three hydrophone sensors forming a triplet makes it possible to compute the back-azimuth uniquely for wave packets with a good signal-to-noise ratio. We analyzed the data of the IMS hydrophone triplets during the month of September 2018 and compared them with in-situ seismic observations in Ioto for the same period.
The IMS hydrophone triplet data made it possible to discriminate the hydroacoustic signals associated with the Ioto volcanic activity. The direction-of-arrival (DOA) was estimated during the entire period of relatively high volcanic activity using cross-correlation analysis. The arrivals from Ioto at the IMS HA station and the in-situ observations showed good correlation. The present study suggests that two-thirds of the arrivals of hydroacoustec signals were associated with volcanic tremors and one-third with the undersea eruptions.