Speaker
Description
Activities of Monowai Volcanic centre have been observed as seismic waves recorded at Rarotonga station (RAR), as well as hydroacoustic waves recorded at Ascension Island (H10). Beamforming has been performed on the hydroacoustic data to verify the source and study the effect of performing calculations with a best beam. The lag time that is calculated by cross correlating seismic and hydroacoustic data corresponds to the known source-receiver distances and the calculated velocity. Finally, the lag time is studied as a function of time in order to observe seasonal change. Travel times between the source and hydrostation H10 do generally increase with decreasing temperature. In the Southern Hemisphere winter however, a sudden decrease of lag time is observed. This might be explained by a different velocity profile of the ocean around the poles, and the formation of sea ice.
