Chile's Hudson Volcano released three huge columns of steam and ash in a cloud more than three miles high today, 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 200 yards to 500 yards 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 seven miles to the south-east, toward Argentina.
The Hudson Volcano has erupted twice in the last 60 years, most recently in August 1991, when it killed an estimated 1.5 million sheep on the Argentine side of the Andean mountain chain.
The volcano is in Patagonia, about 1,000 miles south of Chile's capital, Santiago, and about 500 miles south of the Cordon Caulle volcano that has intermittently grounded thousands of flights in South America since it began erupting months ago.