In the early morning of Feb. 29, park officials, tourists and locals near Mount Nyiragongo in the Democratic Republic of Congo heard an unfamiliar sound: rumbling. What they were hearing was the sound of earthquakes deep below the surface. The movement knocked giant rocks off of the crater walls.

And at the same time, a new vent appeared on a ledge. Since that day, the vent explodes about every 30 seconds, throwing lava up to 90 feet in the air. Most of that lava flows back into the volcano, while the rest of it cools in the crater itself. It’s beautiful, but it’s also a troubling reminder of a 14-year-old catastrophe. The last time the volcano erupted — in 2002 — it killed 147 people and forced 400,000 people to flee the nearby city of Goma.

The eruption effectively split Goma in two, destroying a third of the city. Lava even covered about 80 percent of the airstrips at Goma International Airport, making it almost impossible to evacuate people or get outside aid to survivors. Just like back in 2002, the threat facing Goma today isn’t an explosion, but a fast-moving river of lava that flows out of cracks on the side of the mountain. READ MORE