Fumaroles of the National Park
About Caldera
Akan-Mashu National Park is located along the Eastern Japan Volcanic Belt. The calderas, areas of land that have collapsed when repeated volcanic activity created an empty space underground, are the distinguishing features of this national park. The three calderas within the park—Akan Caldera, Mashu Caldera, and Kussharo Caldera—greatly affect the landscape and the organisms that inhabit it.
Akan Caldera has a diameter of 10 km. According to current research, this caldera is believed to have begun forming after eruptions over 1,300,000 years ago, with the caldera’s current shape being approximately 150,000 years old. Repeated volcanic activity formed the mountains, lakes, and rivers that exist today.
Characteristics of Bokke
One type of active volcanism still visible in the Akan region today are bokke, areas where volcanic gases and boiling mud from underground build up and bubble continuously to the surface of the earth. A type of mud volcano, bokke can be seen on the Bokke Walking Trail along the shore of Lake Akan, as well as around Mt. Furebetsu and the Mt. Hakuto Observatory. The earth remains warm year-round from the geothermal activity around bokke. In fact, snow does not accumulate here, even in the middle of winter. As a result, living things that are usually found in temperate zones, such as madarasuzu (Dianemobius nigrofasciatus), a type of cricket, and plants such as milkworts, forked fimbry, and staghorn clubmoss, can be seen growing around bokke. It is common to see Yezo shika deer gather around bokke during the harsh winter months because of the abundance of food available.
Mt. Meakan is one of Hokkaido’s most active volcanoes. From the summit, volcanic smoke can be seen rising from the raging crater. Most recently, small eruptions occurred in 2006 and 2008.