Mount Asama, historically one of Japan's most active volcanos, burst into life Tuesday morning for the first time in about six years, with the Meteorological Agency reporting a "very small-scale" eruption while also warning people nearby about falling rocks from further eruptions.
"There are no signs that activity may intensify," the agency announced, maintaining the alert at level 2. A 2-km exclusion zone has been in place around the crater, which sits on the border of Nagano and Gunma prefectures, since Thursday.
Later in the day, Prime Minister Shinzo Abe said the government "is stepping up safety measures and gathering information. We will make every effort to deal with the situation."