Residents are being urged to evacuate their homes after one of the volcanoes, in the Caulle Cordon of southern Chile, erupted violently Saturday triggering the government to warn residents of prolonged ashfall.
The volcano was dormant for decades but now the effects can be felt all the way in Argentina as billowing smoke and ash high into the sky and prompting more than 3,500 people living nearby to evacuate.
There were no reports of injuries from Saturday's eruption.
Authorities initially said the Puyehue volcano was involved, but later said the eruption was occurring about 2½ miles (four kilometers) from that peak.
A column of gas six miles (10 kilometers) high and three miles (five kilometers) wide rose from the mountain, according to Chile's National Geology and Mining Service.
Authorities had put the area on alert Saturday morning after a flurry of earthquakes, and the eruption began in the afternoon. The National Emergency Office said it recorded an average of 230 tremors an hour.
About 600 people were evacuated when the first alert went up and hundreds more left their homes after the eruption began.
Rodrigo Ubilla, Chile's undersecretary of labor, said some people near the volcano had decided not to leave their homes because they didn't want to abandon their animals.
Wind carried ash across the Andes to the Argentine tourist town of San Carlos de Bariloche, which had to close its airport.
Officials warned residents of the Bariloche area to take precautions against a possible prolonged ashfall. They urged people to stock up on food and water and to stay home.
The eruption is nearly 620 miles (1,000 kilometers) south of Chile's national capital, Santiago.
Based on reporting by the Associated Press.