In January Dayanthie Weeraratne joined the research vessel Melville in the Pacific Ocean to undertake the next phase of work on the multi-institutional PLUME project to produce seismic images of the mantle beneath Hawaii. Last November postdoctoral fellows Brian Savage and Linda Warren assisted Peter Burkett with the first phase of the work installing seismic stations on the islands themselves. Dayanthie’s trip involved the deployment of ocean-bottom seismometers, the seafloor complement to the land sensors.

Working aboard the ship, operated by the Scripps Institution of Oceanography (SIO), Dayanthie traveled from Hilo out to the area around the Hawaiian Islands, where 35 ocean-bottom seismometers were deployed, 25 by the Woods Hole Oceanographic Institution (WHOI) and 10 by SIO. The ocean-bottom seismometers employ sensors similar to those used on land, though the seafloor packages are powered by batteries rather than solar cells. One additional feature of the ocean-bottom seismometers is that they carry DPG's (Differential Pressure Gauges) to record seismic waves as pressure changes. The instruments will be retrieved in January 2006, when the ocean-bottom data they have recorded will be collected for analysis and the sea-floor instruments will be redeployed for a second year.