Colombians Urge Pacific Northwesterners To Appreciate Lahar Danger

Sep 20, 2013

Visiting scientists from the country of Colombia have a warning for people living in the valleys below our Northwest volcanoes. Get educated about a rare but dangerous phenomenon called a "lahar."

Armero, Colombia was destroyed by a lahar on November 13, 1985. More than 23,000 people were killed when lahars (volcanic debris flows) swept down from the erupting Nevado del Ruiz volcano.
Credit R.J. Janda

Quick! Name the volcano that geologists consider the most dangerous in the Northwest. No, it's not Mount St. Helens even though an eruption there killed 57 people in our lifetime. The answer is Mount Rainier, chiefly because of the hazard posed by volcanic mudflows, also known as "lahars". "In terms of stakes, Mount Rainier wins hands down," says John Ewert, the scientist-in-charge at the USGS Cascades Volcano Observatory. He notes over 100,000 people now live on historic lahar deposits in the Puyallup and Carbon River valleys below Mount Rainier. The setting of Mount Rainier reminds Colombian geologist Marta Calvache of home. In front of a full house at Puyallup City Hall, the deputy director of the Geological Survey Colombia described how recent eruptions of snow-capped volcanoes in her country unleashed torrents of mud and debris. The worst instance in her career killed 23,000 people. That happened in 1985 when lahars swept down from the erupting Nevado del Ruiz volcano.

Calvache: "We hope you don't have to go through this same experience. Learn about our very bad experience. It doesn’t have to happen."

Last month, emergency managers from Western Washington visited Colombia to see a lahar warning system installed there. In our region, lahar detection sensors and downstream warning sirens are installed to the northwest of Mount Rainier and along the Toutle River near Mount St. Helens.

Copyright 2013 Northwest News