The moment Poás volcano spewed a dark cloud about 1,000 feet into the air was captured by a webcam from the Volcanological and Seismological Observatory of Costa Rica.
Tourists were also startled by the explosion, according to local media.
Earlier in February, scientists warned that the mountain’s summit crater was glowing red-hot with molten lava that was also emitting sulfur.
Those geologists said that the temperature inside the dome had jumped during December from 570 degrees Fahrenheit to over 900 degrees.
The small-scale explosion, caused by lava beneath the crater lake making it become super-heated, was not uncommon.
The 8,884-foot mountain has produced other such “steam explosions” throughout its recorded history.
Photo: Volcanological and Seismological Observatory of Costa Rica.