Poor Seattle can’t catch a break. We’ve already covered how the mild-mannered city is particularly prone to giant earthquakes, but it gets even worse: the entire Greater Seattle is at the risk of being buried under a sea of mud.
The area lies downstream from Mount Rainier, which carries the questionable honor of being one of the most dangerous volcanoes in existence. However, this particular danger doesn’t come from soot and magma. Sure, there would be some if it was to erupt, but that would be just the icing on the horror cake.
The true killer would be a lahar, whose nerdy name betrays its potential for destruction. Lahars are giant flows of hot mud, trees and water, rolling forward with the consistency of a zillion tons of wet cement and at speeds up to 60mph.
And they can get big
Urban Seattle could be facing a Lahar as tall 600 freaking feet. How do we know? Because it’s happened before! Around 5,000 years ago, a giant lahar called the Osceola Mudflow filled a part of Puget Sound with three cubic kilometers of hot, steamy, gooey mud. What was once a pristine sea was, in a matter of hours, suddenly 200 square miles of new land.
For comparison, the disastrous 1985 Nevado del Ruiz lahar that killed 25,000 people in Colombia only had 2.5 percent of the volume of the Osceola Mudflow.
So, What Can Be Done?
A lahar detection system was installed in 1998, but it remains loose and incomprehensive. To make matters worse, these mud tsunamis (mudnamis!) are a right bastard to detect: a lahar doesn’t need a volcanic eruption as an excuse to kick in: A sector collapse or some magma leakage could be enough to send a mudnami the size of Godzilla into Seattle.