The alert level for a volcano in southwestern Japan was raised Monday amid increasing seismic activity in the area, according to the Meteorological Agency.

With the level now at 2 on a 5-point scale, people have been warned not to approach the crater of Mount Shinmoe, a 1,421-meter-high volcano that straddles the Kagoshima-Miyazaki prefectural border.

According to the agency, 22 earthquakes originating directly beneath the crater were recorded between noon Sunday and 5 a.m. Monday.

The agency warned of potential eruptions and the risk of airborne rocks within 2 kilometers of the crater, as well as pyroclastic flows within 1 km of the crater.

Shinmoe, which last erupted in June last year, is one of 50 constantly monitored active volcanos in the nation.