3D map of where the methane hydrate site was discovered on the seafloor of Astoria Canyon at 850 m. The exposed hydrate layer is up to 0.5 m thick. Image credit: Susan Merle
The Ocean Exploration Trust Inc. ship E/V Nautilus, with several NOAA-PMEL and Oregon State University CIMRS scientists aboard, is using the latest midwater sonar technology to map out methane seeps along the Cascadia continental margin this month. PMEL/CIMRS scientists report that, after locating extensive bubble plumes of methane in Astoria canyon at 850 m, the remotely operated vehicle Hercules visited the site and found an exposure of methane hydrate and gas bubbles streaming out of the seafloor. The hydrate, a mixed water/methane ice phase, is present over extensive areas of continental margins, but has only rarely been observed exposed at the seafloor along the Cascadia margin. Why the hydrate is exposed at this location in association with the methane gas seepage is a topic of discussion among the scientists aboard the Nautilus and those ashore participating remotely via the internet. The E/V Nautilus is a unique platform with extensive telepresence capability that enables scientist aboard to interact with those in the broader scientific community and the public ashore. Dives with the Hercules are broadcast live over the internet and can be viewed at http://www.nautiluslive.org/