Volcano...

JAKARTA, Indonesia (CNN) -- More than 20,000 people will need to be evacuated to crowded shelters, one filled to three times its capacity, as experts predicted a massive eruption from one of Indonesia's most dangerous volcanoes.

Mount Merapi has been rumbling for about a month, but an increase in lava flow in the past day has triggered concerns that a nasty eruption could be imminent.

Indonesian authorities ordered the evacuation of thousands of residents near Merapi on Saturday, and the United Nations is predicting that as many as 80,000 people could be displaced by an eruption, depending on which way the lava flows.

"What the officials are saying is that we're going to have a larger eruption than what we're seeing right at the moment," volcanologist Catherine Hickson of Thompson Rivers University in Canada said.

"We call them Merapian-style eruptions because essentially we have a dome that forms and we create these hot pyroclastic flows which kill people. So we actually name a style after this because it is so frequent."

A pyroclastic flow is an avalanche of hot ash, pumice, rock fragments and volcanic gas that can rush down the side of a volcano at a hundred miles per hour.

"Anyone or animal that is caught in its path is immediately, essentially incinerated," she said...

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