Stunning Nighttime Pictures of Chilean Volcano Erupting

Villarrica, one of Chile's most active volcanoes, awoke with a vengeance this week, launching lava bombs and an ash cloud thousands of feet into the air. The nearby towns of Pucon and Conaripe were evacuated as a precaution.

This 9,330-foot-tall (2,850-meter) peak is known as a stratovolcano or a composite volcano, according to the Smithsonian's Global Volcanism Program. They're formed by an accumulation of lava and other debris shot out of cracks and craters during eruptions. (See stunning pictures of blue flames leaping from a volcano.)

A stratovolcano can have vents at its summit as well as along its flanks, and eruptions can occur through any one of them. More than 30 small cinder cones and vents dot the sides of Villarrica.

Major eruptions in 1985 and 1992 added lava layers and two new cones to Villarrica. Historical records of this volcano's eruptions go back to 1558. (Watch an underwater volcano form a new island near Japan.)

This week's eruption was characterized by so-called strombolian explosions, according to the Smithsonian. Caused by the sudden release of gases that have built up within a volcano, strombolian explosions result in spectacular fountains of lava and debris.

The ash clouds that balloon over these eruptions can also spawn lightning, thanks to the static electricity that builds up. (See lightning storms blossom over another Chilean volcano.)

These fireworks pose an additional potential hazard to the surrounding population in the form of mudslides and floods. Villarrica is covered with roughly 15 square miles (40 square kilometers) of glaciers, which are now being peppered with flaming chunks of melted rock. Rivers are rising as a result of the melting snow and ice, reports USA Today.

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