The Meteorological Agency on Wednesday raised the alert level for a volcano on Kuchinoerabu Island, urging residents there to prepare for possible evacuation.
The level now stands at the second-highest of four on a scale of five, up from two, which only restricts entrance to areas close to the crater, the agency said.
The decision to raise the alert level comes after increased seismic activity was observed on the island, which is in Kagoshima Prefecture. It warned people to stay alert against possible pyroclastic flows and falling volcanic rocks.