http://news.yahoo.com/rapidly-inflating-volcano-creates-growing-mystery-142805969.html

Researchers from several universities are essentially working as geological detectives, using a suite of tools to piece together the restive peak's past in order to understand what it is doing now, and better diagnose what may lie ahead.

It's a mystery they've yet to solve.

Uturuncu is a nearly 20,000-foot-high (6,000 meters) volcano in southwest Bolivia. Scientists recently discovered the volcano is inflating with astonishing speed.