The Meteorological Agency has lowered its alert level for Mount Aso in Kumamoto Prefecture, citing diminished volcanic activity following its explosive eruption in October.
With no major eruptions observed since then, the Meteorological Agency on Tuesday lowered the alert level for the 1,592-meter peak from 3 to 2 on the 5-point scale. Under level 2, people are advised not to approach the crater.
“A small-scale eruption could still occur and vigilance is needed against ejection of large ash deposits and pyroclastic flows within a 1-km radius of the crater,” the agency said.
The alert level was downgraded because the amount of volcanic gas emission has fallen this month and only small volcanic earthquakes have been observed recently, officials said.
Mount Aso erupted at around 1:46 a.m. Oct. 8, spewing volcanic ash up to 10,000 meters into the sky. Ash falls were observed in Kumamoto, Oita and Ehime prefectures.
The agency believes a magma vapor eruption occurred when underground water came in contact with magma.