A volcano in Chile has erupted twice in a day after being dormant for more than half a century.

A state of red alert remains in force after the second blast from the Calbuco volcano in the south of the country, Chile’s National Geology and Mining Service said via Twitter.

The first eruption about seven hours earlier was the first by Calbuco in 54 years. It forced the evacuation of about 5000 people and sent a column of ash high into the sky.

• Villarica volcano eruption rocks Chilean town
• Five horror stories from a travel writer

But there were no immediate reports of injuries.

Another absolutely incredible image from the volcano eruption in Chile via @lopezdoriga pic.twitter.com/OwWzLztRjS

— Adrian Linares (@Adriansweather) April 23, 2015

Officials ordered an evacuation for a 20-kilometre radius around the volcano and the interior ministry rushed in the army to temporarily take control of the province of Llanquihue and the town of Puerto Octay.

Emergency measures were also in place in neighbouring Argentina, where the picturesque city of Bariloche – about 100 kilometres from the volcano – said it was anticipating the arrival of ash clouds within hours and warned people to stay at home.

Column of ash and lava spewing from the Calbuco volcano in Chile. Photo: Getty

Puerto Montt, over the border from Bariloche and the largest Chilean city in the area, was already blanketed in a cloud of ash.

“People are very, very frightened,” said Gervoy Paredes, mayor of Puerto Montt.

“The situation is pretty complicated,” he added, saying reports indicated the Blanco river was flooding because of ice melt triggered by the eruption.

Airlines cancelled flights as the towering, mushroom-shaped ash cloud rose from Calbuco’s snowy peak.

Schools also suspended classes in the region.

Television images showed large traffic jams and long lines at petrol stations in Puerto Montt, where a red alert was declared, along with nearby Puerto Varas.

“I would like to call on the population to remain calm and stay informed,” said Interior Minister Rodrigo Penailillo.

“The police have given orders and begun to evacuate.”

The initial evacuation involved about 270 families, but could be expanded, officials said.