methane-plume-washington Published October 14, 2015 at 720 × 303 in New methane scare off Washington coast begs the question: did anybody look for these before? Sonar image of bubbles rising from the seafloor off the Washington coast. The base of the column is 1/3 of a mile (515 meters) deep and the top of the plume is at 1/10 of a mile (180 meters) depth. CREDIT Brendan Philip/University of Washington