Chicago Sun-Times

DEBRIS ‘ AVALANCHE’ LEFT LITTLE HOPE OF ESCAPE

More than 200 dead, scores still missing in Colombia disaster

- Trevor Hughes @ trevorhugh­es USA TODAY

A lethal mix of gravity, water and dirt combined to create an “avalanche” that tore through a small Colombian city, killing more than 200.

What happened in Mocoa is known as a “debris flow,” which came during an unusually wet season, topped off by a shorter period of intense rain, federal landslide scientist Jonathan Godt says. He said he reviewed images and video of the Mocoa disaster, noting the mountains surroundin­g the city.

“That very heavy rainfall makes the soil like goo, makes it easy to flow. It just starts sliding down the hillside,” says Godt, coordinato­r of the U. S. Geological Survey’s landslide hazards program. “My guess is that it was moving very fast and would have been full of rock and boulders and pieces of buildings. For someone experienci­ng it, an avalanche would be a very accurate descriptio­n.”

Residents and rescue workers clawed through the sea of mud and debris Sunday in a desperate search for survivors, one day after surging rivers overwhelme­d the city. Witnesses reporting hearing buildings shuddering and vibrating as the flow crashed throughMoc­oa. Scores remain missing since the deluge struck after midnight Saturday when many people were sleeping, washing away trees, vehicles, houses and everything in its path. Pictures posted to social media show bridges wiped away and piles of debris in the town center.

The avalanche is the fourth- worst weather- related disaster to ever strike Columbia, says Jeff Masters, director of meteorolog­y for Weather Undergroun­d. He says the damage is great because the city was built in a potentiall­y dangerous location: at the bottom of mountains, alongside a riverbed.

Godt, who has created small- scale landslides in Oregon for research, says debris flows like this one can be more devastatin­g than a flood because the water gives the flow speed and the debris gives it extra punch.

“Because it has all of this water behind it, it’s a really dense, heavy flood,” he says. “Because it’s so dense, it has a lot more momentum and destructiv­e power than water alone.”

Godt says flows like this happen anywhere there are mountainou­s regions. He says the damage varies depending on how steep the surroundin­g hillsides are and whether trees or other vegetation help “anchor” the wet soil in place. Hillsides burned clean by forest fires or clear- cut via logging tend to be at a higher risk for slides, he says, because there’s less to retain the soil.

Masters says the fact the disaster struck at night compounded the danger.

“The debris impacts the houses, knocks them down, so you have a much lower chance of surviving.”

 ?? FERNANDO VERGARA, AP ?? The torrent of water, mud and debris swept throughMoc­oa, Colombia, early Saturday when many people were sleeping.
FERNANDO VERGARA, AP The torrent of water, mud and debris swept throughMoc­oa, Colombia, early Saturday when many people were sleeping.

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