Story highlights Almost 2 feet of ash fell in some areas

Authorities evacuate 4,400 people

The last time Calbuco erupted was 1972

(CNN) Chile's Calbuco volcano erupted twice in 24 hours, the country's National Geology and Mining Service said early Thursday.

The agency said it was evaluating the spectacular nighttime eruption, but indicated it was "stronger than the first one."

About 23½ inches (60 centimeters) of ash fell in some places, according to the Ministry of Interior and Public Safety.

Authorities issued a red alert for the towns of Puerto Montt and Puerto Varas in southern Chile. Both are popular tourist destinations.

A 12-mile (20 kilometer) exclusion zone was established around the crater. Military and police forces were assisting with the evacuations of more than 4,400 residents, the Interior Ministry said.

American Helen Rodgers witnessed the volcano erupt from the Hotel Patagonico in Puerto Varas, a popular tourist destination.

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