Volcanic tremor amplitude increased at Asoson at around 2100 on 2 May, prompting JMA to raise the Alert Level to 2 (on a scale of 1-5) at 2255.
The public was warned to stay at least 1 km away from the crater.
Sulfur dioxide emissions were low, at 200 tons per day on 3 May, and white steam plumes rose as high as 300 m above the crater rim.
Source: Japan Meteorological Agency (JMA)