Chile's Hudson Volcano released three huge columns of steam and ash that combined in a cloud more than 3 miles (5 kilometers) high on Friday, threatening a much larger eruption that had authorities in Chile and Argentina on red alert.
Chilean officials evacuated 119 people from the immediate area, and other nearby residents prepared to flee as melting snow and ice caused the Aysen river to overflow its banks.
The steam and ash was coming from three craters, ranging from 650 feet (200 meters) to 1,600 feet (500 meters) wide, and with earthquakes shaking the mountain, a major eruption could occur within hours or days, Chile's national geology service said. Already, a plume of ash and steam spread 7.5 miles to the southeast, toward Argentina.
The Hudson Volcano has erupted twice in the last 60 years, most recently in August 1991, when it piled ash 18 inches (45 centimeters) high and killed an estimated 1.5 million sheep on the Argentine side of the Andean mountain chain.
The volcano is in Patagonia, 995 miles (1,600 kilometers) south of Chile's capital, Santiago, and 470 miles (750 kilometers) south of the Cordon Caulle volcano that has intermittently grounded thousands of flights in South America since it began erupting months ago.
Coihayque is the nearest large town in Chile to the Hudson, and just over the Argentine border, the towns of Los Antiguos and Perito Moreno were mobilizing for the worst. In a major eruption, prevailing winds could blow its ash across the continent, cutting off supply routes and air travel to far-southern Argentina.