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.”
NHK showed the volcano spewing gray volcanic fumes into a cloudy sky at about 9:20 a.m. Tuesday. The video was captured by a surveillance camera west of the crater.
The eruption was initially detected at about 9:30 a.m. by an employee staffer at a tourist facility, who informed the Meteorological Agency that volcanic ash was falling about 4 km north of the crater, NHK quoted the agency as saying.
A reporter at the Asama Volcano Museum, located on the Gunma side of the mountain, said he could smell no odor to indicate an eruption and that no ash was falling at that site.
“Mount Asama is a very active volcano, said Minoru Takeo, a professor at the University of Tokyo Earthquake Research Institute. “There’s high possibility there will be sustained activity.”
The volcano looms over the busy tourist resort of Karuizawa, Nagano Prefecture, and scenic woodland filled with vacation lodges. Nearby municipalities warned tourists and hikers of the risks.
“It looks like the eruption is small for now, but it’s a concern that tourists may be discouraged from visiting,” said a female employee at Kaikoen, a park on the site of a former castle in Komoro, Nagano Prefecture, southwest of Asama.
Numerous volcanic tremors have been recorded in recent days at the mountain, while output has risen of volcanic sulfur dioxide gas. This prompted the agency to raise its alert from level 1 to 2 on Thursday.
The eruption came after 69 volcanic tremors were recorded Monday. By 3 p.m. Tuesday, another 64 tremors had occurred and a small amount of ash had fallen as far as 4 km north of the volcano.
Asama has erupted many times in the past. In 1783, a large-scale eruption resulted in more than 1,000 deaths and the destruction of many homes. There were 398 eruptions in 1941 and 287 eruptions in 1954.
Most recently, an eruption in 2009 deposited volcanic ash across the southern stretches of Kanto, but the eruption was classified as small-scale.