The Meteorological Agency has raised the volcanic alert for Mount Meakandake in Hokkaido, saying a small eruption is possible.
The five-point threat level for the 1,499-meter mountain in Akan National Park in eastern Hokkaido was raised on Tuesday from 1, "be mindful that the volcano is potentially active," to 2, or "do not approach the crater."
The nearby municipalities of Kushiro and Ashoro restricted climbing within 500 meters of the crater.
But the alert did not impact a hot-spring resort area at Lake Akan about 8 km away, the Kushiro Municipal Government said.
The Meteorological Agency said the number of small volcanic earthquakes around the mountain have been increasing since Sunday, although they were too small to be felt by humans.
An aerial observation Monday and an on-site investigation Tuesday confirmed increased volcanic smoke near the crater, the agency said.