Ichinomegata is a fresh water lake and is a good example of a maar (an explosion crater). The three lakes, Ichi-no-Me gata, Ni-no-Me gata, and San-no-Me gata, form the Megata volcano group.
A maar is a round crater caused by a phreatomagmatic eruption due to the contact of water and magma. Water often pours into such a crater and is thus turned into a lake. The Megata volcano group is the only maars in Tohoku region and rare examples in all of Japan. Only a few others exist on Izu-Oshima Island and in Kagoshima Prefecture.
Ichi-no-Me gata has also attracted worldwide attention for the observation of substances that have erupted from the depths of the Earth. In addition, scientists recently discovered varves in which is recorded yearly changes in the lake. Further research is needed for the historiography of the earthly environment.
Specified Date: July 26, 2007
Area: 524,367 m2
