EOI scientists aboard E/V Nautilus June 12-29 used multibeam sonar and a remotely operated vehicle to more fully document and characterize the undersea methane sites from Northern California to Washington. Up until a few years ago, only 100 methane “seep sites” had been identified primarily by fisherman using their fish-finders observing the acoustic reflections of the gas bubbles. Beginning in 2016, EOI scientists began a more systematic mapping of the seeps using new sonar technology on the E/V Nautilus, owned and operated by the Ocean Exploration Trust. About 25 percent of the potential methane seep water column area has now been mapped and analyzed. This year, EOI researchers embarked again on the Nautilus to continue surveying additional methane sites by night. During the day a remotely operated vehicle (ROV) collected samples of gas, methane hydrate, seep water, fauna and rocks at these sites. Analyzing these samples in conjunction with a more complete inventory of sites will help scientists understand the origin of the seeping methane and its impact on the ocean environment.
More information about the Cascadia Margin expedition:
More information about the methane research and expedition can be found at:
NOAA PMEL EOI Program Methane Studies:
Oregon State University Press Release: