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Massive Storms Lead to Elevated Landslide Hazards for the West Coast

Saturated slopes can be very bad news. The good news: Congress may be ready to do something about it

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


Greetings from Snowlandia! Seattle just survived several consecutive snowpocalypses, which dumped roughly two years' worth of snow upon us in less than two weeks. This is the city that shuts down when there are a mere couple of inches on the roadways (snow + hills - efficient snow removal gear = doom). So you can imagine what 20 inches did. People were sledding down the hills in our complex's parking lot, and several trees came down, one right outside our bedroom windows. So it's been exciting.

The entire Pacific Northwest has endured some pretty gnarly weather this month. But it's about to get back to our normal February low-to-mid 40s and the occasional Pineapple Express. Which means the roads and parking lots will be clear in a matter of days. Great, right? Except not. Because when you get a ton of snow, then melt it off really quickly, you get plenty of flooding and the hazard of landslides galore.

The flakes had barely stopped falling before the National Weather Service was warning about the landslide risk. And that's why we're talking weather on a geology blog: when soils get saturated, they're prone to catastrophic failure. Fortunately, we haven't seen another Oso yet, but with so many steep slopes covered with glacial detritus balanced precariously on thick layers of glacial lake clay, it's only a matter of time before we see another tragic slide.


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And, of course, you don't have to be in the Seattle area to be at risk. Anywhere with steep slopes and unstable soil and rock will do. If you throw in disturbed or burned vegetation, like California has after the devastating fires last fall, you'll see even worse mudslides. With root systems dead, there's very little left to hold the soils in place.

Landslide hazards are a fact of live for tens of millions of Americans, which is why it's great that we may see some movement on landslide hazard assessment and mitigation on a federal level:

If passed, the National Landslide Preparedness Act would create an inventory of 3-D maps that anyone could look up. A bill introduced Thursday makes minor updates to a similar proposal from two years ago that failed to come up for a full U.S. House vote.

The federal law would direct the U.S. Geological Survey to create a National Landslide Hazards Reduction Program. Goals would include setting research priorities, coordinating work among different agencies and developing a national landslide database. Not only would the database be used to gauge risks, but also impacts on health, the economy and the environment.

“The work that’s happening at the local level and the federal level could be readily combined and we would have that information available for people to see,” DelBene said.

The act would provide an initial $37 million in funding each fiscal year. The bulk of the money — $25 million — would go to the U.S. Geological Survey. Another $11 million would go to the National Science Foundation. The National Oceanic and Atmospheric Administration also would receive $1 million to work on an early warning system for post-wildfire debris flows.

This is very necessary work. I consider it on par with volcano monitoring and flood control as far as essential hazard mitigation goes. When lives and homes can be swept away in a matter of minutes, it pays for us to know where the risks are, preferably before we build on dangerous sites. For those already living and working in landslide-prone areas, it helps them mitigate the risk and learn the warning signs so they can hopefully live safely. Let your representatives know this legislation is important to you.

The Washington Department of Natural Resources has some very excellent tools on this page. The maps may pertain to Washington State, but the tips on how to recognize signs of an impending landslide and what steps to take in order to reduce your risks are relevant around the world. I encourage you to take a look. And if you live in Washington state, look here to see if you're living on or near a currently mapped slide.

If you're not lucky enough to reside here, your local and state agencies may have similar resources for you to consult. If you can't find them online, you can call or email your local equivalent of the DNR for details.

Stay safe, my friends!

This poor tree in our back yard didn't survive Snowpocalypse. Credit: Dana Hunter