Description
Lake Mashu is a endorheic crater lake formed in the caldera of a potentially active volcano. It is located in Akan National Park on the island of Hokkaido, Japan. The lake has been called the clearest lake in the world. Mashu volcano is located on the east wall of the Kussharo caldera (26km east-west, 20km north-south), and formed as a stratovolcano no later than 34,000 years ago (Hasegawa et al., 2009), but approximately 7,000 years ago a large eruption formed a caldera (the Mashu caldera, 5.5km east-west, 7.5km north-south). Inside the Mashu caldera is Lake Mashu, and in the center of the lake is a dacitic lava dome (Kamuishu Island). On the southeast wall of the caldera is Kamuinupuri (Mashudake), a small andesite and dacite stratovolcano. The SiO2 content is between 52.4 and 73.0 wt %.
