Mt. Iwo
Mt. Iwo is a volcanic peak in the Kirishima mountain range, which consists of a cluster of over 20 volcanoes. Created during an eruption in the Edo period (1603–1867), Iwo is the youngest of the Kirishima volcanoes. While it has been active for the past several years, its activity has been limited to releasing water vapor from vents and the mouth of the volcano.
Mt. Iwo has erupted several times since its formation, with recent activity beginning in 2013, when tectonic earthquakes were detected. In July 2015, gas was observed escaping from the south side of the volcano’s mouth, and on April 19, 2018 an eruption occurred on the south side, followed by activity on April 20 beginning on the west side of the volcano.
On April 21, 2018, an influx of hot water from the volcano containing sulfuric acid, arsenic, and other heavy metals was found to have contaminated and clouded the Nagae River, a tributary of the Sendaigawa River, one of Kyushu’s major waterways. At Oharabashi Bridge in Ebino, the river’s pH level dropped to 2.1, signaling a high level of acidity. This change in water quality forced a small number of farming households located downstream in Miyazaki Prefecture and neighboring Kagoshima Prefecture to halt rice production for 2018.
Despite the dangers, there is a long history of humans thriving in this volcanic region. In recent history sulfur was mined here. The hot springs heated by the volcano, moreover, have been enjoyed since antiquity. Local people and tourists alike come to admire the Miyama Kirishima azaleas, which grow profusely on the mountainside. During the late spring to early summer, the blossoms paint the mountainside in shades of pink and purple.