Costa Rica's Turrialba volcano belched a column of gas and ash up to 3,280 feet (1 km) into the air on Thursday in its most powerful eruption in two decades, and local authorities started to evacuate residents from the surrounding area.

Four explosions emanated from the volcano in central Costa Rica on Thursday, and ash reached parts of the capital San Jose some 30 miles (50 km) away, where the airport was closed. It was the volcano's strongest eruption since 1996.

"We have recommended the evacuation of people and small animals as a precaution. The last explosion was very strong," a spokesman for the Volcanological and Seismological Observatory of Costa Rica (Obsivori) said.

Costa Rica's emergency services ordered the closure of access roads near the volcano, which is major tourist draw, and were evacuating a radius of just over a mile around the volcano.

Turrialba erupted in October, when it also sprinkled the capital with ash after it spewed magma for the first time since around 1863.