Large mass of methane hydrate exposed on the seafloor, photographed by the Super-Harp ultra high-resolution, high-sensitive video-camera of the ROV Hyper-Dolphin of JAMSTEC. The width of the manipulator is approximately 18 cm. Collapse structure zone on the Umitaka spur. Water depth is 900 m. White materials at the wall upper-left portion of the wall are also methane hydrate. Methane hydrate exposed to sea water is expected to be dissolved as the seawater is under-saturated with methane. The large hydrate block in the photo is surrounded by a sharp and broken surface. The exposed methane hydrate block is considered to be a broken remnant of a large mass that collapsed and floated up to the sea-surface due to gravity imbalance and gas pressure below the hydrate.
(Ryo MATSUMOTO; photo: courtesy of JAMSTEC (Natsushima NT07-20))
