Mount Sinabung, on the Indonesian island of Sumatra, has been one of the world’s most active volcanos since it began erupting again in August 2010, after four centuries of dormancy. But for the past five years, the eruptions have been moderate — until last week.

On the morning of February 19, the volcano erupted in a massive explosion that sent volcanic ash at least 55,000 feet (10.4 miles) into the sky, making it the largest such eruption since this period of activity started in 2013.

A video of the event went viral on Reddit earlier this week. It shows an otherwise perfectly blue sky above a tropical village, which is about to be covered by what looks like grey clouds of ash spreading out in seeming slow motion across the earth. In fact, this is hot gas and ash spewing from the volcano’s summit. The video also shows, another ballooning plume of ash rising high into the sky above. Towards the end of the video, as the shooter is moving towards the distant volcano for a better shot, you can make out a person and an animal on the road running away from the eruption.

This video of the eruption went viral on Reddit this week. 

Sinabung is a stratovolcano, built up by layers of hardened lava, pumice stone, tephra, and volcanic ash. It lies within the “Ring of Fire” — the chain of 200-plus active volcanoes in the Pacific Ocean. After lying dormant for over 400 years, Sinabung violently erupted in August of 2010, There have been a number of smaller eruptions since then — ten since the initial 2010 event — but its increased activity has fortunately put local officials on high alert, preventing major casualties.

Fortunately, no casualties were reported as a result of this eruption, though the island was put on high alert, as hot gas and ash made its down the sides of the volcano before spreading out in a 3 mile diameter, while ash falls were also recorded as far as 160 miles north. In some areas, visibility decreased to a mere five meters.

The only “casualty” — this time, at least — was Sinabung itself, as the force of the eruption blew off 56.5 million cubic feet from the volcano’s peak.

The eruption as seen from space