Methane hydrates, viewed as a next-generation energy source, have been found under the sea in two areas of Japan's exclusive economic zone, a group of researchers said.
The group also said it has collected methane hydrates in layers several meters below the seabed at a spot in the Sea of Japan and another in the Sea of Okhotsk off Hokkaido.
The group, led by Meiji University, Kitami Institute of Technology and the University of Tokyo, said Monday the discovery is only "the first step" toward determining whether the substance is a viable energy source.
The group also said it has found an undersea column of methane gas off Tottori and Shimane prefectures, a discovery that suggests the existence of methane hydrates.
Methane hydrate, a solid consisting of methane and water molecules, is being eyed as a potential alternative to natural gas, which resource-poor Japan has imported in vast quantities due to the Fukushima nuclear crisis and shutdown of reactors nationwide.