Mount Sakurajima, an active volcano in Kagoshima Prefecture, could release its largest amount of ash in two decades this year, researchers said.
The total amount of volcanic ash emitted from Sakurajima from January to last month was more than two times larger than all of last year, when the mountain saw a record number of eruptions for a year, said Masato Iguchi, a professor at the Sakurajima Volcano Research Center, a part of Kyoto University's disaster reduction research institute.
If the pace of activity is sustained, the amount of ash for the year could be the most in 20 years.
"Both the number of explosions and amount of ash fall are on the rise and volcanic action is expected to become more active," Iguchi said Wednesday.
The ground around Sakurajima has been swelling since the buildup of magma appears to be increasing, Iguchi said.
The mountain's Showa crater has been active since around 2008, while the Minamidake crater erupted last month for the first time in about a year and a half.
In 1914, a deadly eruption on Sakurajima killed 58 people.