A major eruption occurred in 1947. On December 21, 1994, the volcano expelled ash and gas that were carried in a radius of 25 km in the wind. Nearby towns were evacuated and volcanologists began preparing for another eruption. In December 2000, tens of thousands of people were evacuated after scientists had sounded the alarm. The volcano had some violent convulsions, falling to a relatively moderate level of activity. On 1 December 2007, the volcano erupted, emitting a column of ash more than two miles high.