[S06-P] Poster

[S06-P-02] Long-range underwater acoustic propagation from controlled underwater sources received at IMS hydroacoustic stations

^○Tomoaki Yamada¹, Georgios Haralabus², Mario Zampolli², Kevin Heaney³ (1.The University of Tokyo, Tokyo, Japan, 2.CTBTO, Vienna, Austria, 3.OASIS Inc., Lexington, USA)

Controlled impulsive scientific underwater sound sources in the Northwestern Pacific used for lithosphere studies, and observed at two IMS hydroacoustic stations in the Pacific Ocean were studied. Although the energy released from these sources is significantly smaller than that of nuclear explosions, the signals were recorded by ocean bottom seismometers and IMS hydroacoustic stations thousands of kilometers away from the source. These experiments provide calibrated yield, time and locations for long-range acoustic transmissions, which enable the examination of the physics of long-range acoustic propagation. The IMS stations employed in this study were HA03 (Juan Fernandez Island) off the coast of Chile in the Southeastern Pacific, and HA11 (Wake Island, USA) in the western Pacific. Both stations have two triplets of hydrophones located in the SOFAR channel and monitor the oceans for signs of nuclear explosions. HA03 detected sources that were located above flat terrain at distances of 15,000 km across the Pacific and above the landward slope off the coast of Japan at distances of 16,000 km across the Pacific. These records demonstrated that bubble pulse characteristics in the signal could be preserved over the long propagation distances.