The Villarica volcano near Pucón, Chile erupted early Tuesday morning, spewing a spectacular fountain of lava and ash that extended hundreds of meter into the air.
According to Chile's National Emergency Office, Villarica erupted around 3 a.m. local time, and has forced more than 3,000 people to evacuate from surrounding towns. Fortunately, the eruption wasn't unexpected; yesterday, Chile's National Geology and Mining Service issued an orange alert after confirming a spike in local seismic activity, which, a press release noted, "has increased three times compared with early February," when the organization had previously declared a yellow alert.
Villarica is one of the most active volcanos in South America, and last erupted in 2000. (According to Chile's Ministry of Mining, Villarica's last major eruption was in 1985. See here for historical photos of Villarica's eruptions.) Geologically speaking, Villarica is a stratovolcano, a class regarded as the most violent on Earth, and the category to which Mount St Helens belongs. The high silica content and viscous lava of these violent volcanoes tends to trap gas in ways that result in more explosive eruptions than what we typically see from, say, the relatively gentle volcanoes of Hawaii. These stratovolcanoes can eject ash high into the atmosphere, spill lava and pyroclastic flows down their flanks, and melt snow into fast-moving lahars (aka, boiling-hot, fast-moving landslides.)
Time-lapse footage acquired by Proyecto Observación Villarrica Internet (POVI) shows the volcano growing increasingly violent before climaxing in an eruptive pulse, clearly visible around the 1:30 mark:
The volcano was violently active for only a few minutes (and accompanied by lightning) before dying down, but photos taken a few hours after the eruption show the volcano smoldering in the bright light of morning.
While photos like the ones above show traces of small lava flows, Reuters reports that a major lava flow is not currently expected, though Luis Lara, head of Chile's National Geology and Mining Service, says that could change.