[M-AG37] CTBT IMS Technologies for Detecting Nuclear Explosion and Their Applications to Earth Science

[MAG37-P02] Detections of hydrocoustic signals associated with volcanic eruptions at Kadovar Island, Papua New Guinea, using CTBT IMS hydrophones

*松本 浩幸¹、Zampolli Mario²、Haralabus Georgios²、Stanley Jerry²、Robertson James²、Meral Özel Nurcan² (1.Japan Agency for Marine-Earth Science and Technology、2.Comprehensive Nuclear-Test-Ban Treaty Organization)

Following an eruption series at Kadovar Island, Papua New Guinea, the hydroacoustic datasets acquired by CTBT International Monitoring System (IMS) hydroacoustic (HA) hydrophone station HA11, Wake Island, were examined. HA11 is located approximately 3500 km northeast from Kadovar. Active eruptions restarted in January 2018 after an extended quiet period that lasted approximately three centuries. Cross-correlation analysis using two months of HA11 hydrophone triplet data showed that the cumulative number of HA detections increased with time after the start of the volcanic eruption series. According to local observations of Kadovar, a first eruption at the summit of the island was followed by four additional new vent spots and two vents were created underwater near to the shoreline. Our analysis suggests that the hydroacoustic signals detected by HA11 were associated with underwater volcanic eruptions close tothe shoreline. Additionally, a lava dome collapse accompanied by some small tsunamis occurred on 09 February 2018. The present study suggests that a series of explosive bursts followed by a peculiar hiss, recorded by HA11, may constrain the time of this lava dome collapse event at Kadovar to 00:33 UTC on 09 February 2018. Given the compatibility of this observation with the computed source time of a tsunami, which was reported by eyewitnesses on the nearby island of Blup Blup, the authors interpret this particular hydroacoustic signal as being a remote observation of the tsunamigenic event. The present study demonstrates the potential contributions of the IMS HA stations data to the remote monitoring of volcanic activity over large ocean areas.