Oyunuma Pond, Goshogake was added to Your Favorites!
Towada-Hachimantai NP, Akita
Claim this place to tell your story your way.
Oyunuma is actually a group of ponds: escaping steam carries sediment from underwater mud volcanoes and mud pots upward, where it piles up to form the banks between the basins. The landscape helps build its own shorelines.
Oyunuma has an east–west divide: the eastern side is no longer active, though submerged mud volcanoes and mud pots remain as clues to its past. On the western side, activity continues and the water is over 83°C.
In measurements made in 1982–83, the surface averaged 83.4°C in 1982, while water just above the pond bed reached about 120°C. Researchers’ heat-budget model estimated that roughly 9 tonnes of 120°C steam entered the pond each hour.
Oyunuma is a sulfur sink as well as a hot pool: a 1985 study estimated that hot water and vapor carried sulfur compounds into it, where they settled on the bottom. Its model put the incoming H₂S-bound sulfur at about 5.1 kg per hour.
