The Puyehue volcano in southern Chile has erupted for the first time in a half century, sending a column of gas about 10 kilometers into the air.
Authorities say they plan to evacuate 3,500 people from areas around the mountain, which is nearly 1,000 kilometers (about 620 miles) south of the Chilean capital, Santiago. The eruption also prompted authorities to shut a border crossing into Argentina.
Emergency officials recorded many small earthquakes in the region Saturday.
There have been no reports of injuries.
Chile has the second largest volcanic chain in the world after Indonesia. Of some 2,000 volcanoes in Chile, about 500 are active. Other Chilean volcanos, Llaima and Chaiten, have erupted in recent years.