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March 19, 2015

UW geologist, engineer reflect back one year later on nation’s deadliest landslide

On March 22, 2014, the deadliest landslide in U.S. history struck Oso, Washington. The year since then has been relentless for University of Washington researchers who helped answer questions, survey the aftermath and address issues raised by the disaster that killed 43 people.

David Montgomery, a UW professor of Earth and space sciences, and Joseph Wartman, a UW associate professor of civil and environmental engineering, sat down last week to look back at the past year.

What were those first days like for you, as reports were coming out about the mudslide?

DM: I remember scrambling for information. The people who really knew what was going on were onsite, but they had their hands full and they didn’t need to be bothered by the media. So that role fell to people like Joe and I, who were at a bit of a distance, but who had some expertise. Yet we didn’t have direct access to the slide because we weren’t part of the rescue and then recovery efforts. I spent a lot of time simply trying to figure out what happened, so I could communicate without making major errors.

JW: For me, it was trying to get a sense of whether there was anything to the initial human loss estimates. It’s hard for us in a developed nation to think that there can be that kind of large loss of life from a single event. Those are numbers you read about in Afghanistan or Central America or Latin America, where they don’t necessarily have the same land-use controls. Often, the loss estimates go down very quickly as people continue to show up to community centers, and often the initial estimates are quite exaggerated. But that wasn’t the case here.

Were there any geological clues that this might happen?

JW: I remember having a very strong reaction the first time I looked at the Lidar data. You can immediately see there are other large-scale landsides in the immediate vicinity of Oso. It was striking, and it was also upsetting to see as the aftermath was playing out, because you could clearly see a history of this kind of event at that location.

DM: If you look at the hazard maps that were available to the residents of Steelhead Drive before the 2014 landslide, they all showed a landslide on the valley wall across the river, the old Hazel landslide. There was no landslide hazard depicted on the valley bottom where people were living, yet we know that the risk from landslides is not just from where they are, but how far they may go and how likely that is. Without such information people can’t make fully informed decisions about whether they’re willing to buy a house in a landslide-prone area.

JW: When I talk with people from the Oso area, I’ve been surprised to hear how many people say they simply weren’t aware that anything like this could have happened. So I think there’s some breakdown there, because the scientists who look at the Lidar data can in an instant realize that it certainly falls within the realm of possibility, and has happened before in the not-so-distant past.

How would you describe the past year?

JW: In some ways it seems like it’s been much, much longer than a year. I think we compressed a lot of science into a very short amount of time. Sometimes the investigation takes a couple of years, but many basic questions about this event were answered quickly. Yet there’s so much work to do in terms of informing the public. People have important questions about landslide hazard risk, and I can’t keep up with all of the inquiries.

What was it like investigating a geological disaster so close to home?

JW: All of the disasters I’ve studied have occurred in locations I’ve had to fly to. This is the first time I’ve worked on a geological disaster where I’ve met the survivors, or family members of survivors, and it’s become much more personal.

DM: Most other big disasters, like Mt. Pinatubo in the Philippines, we’ve gotten there years afterwards when it’s not so fresh and so raw. And it’s farther from home. Working on the site itself was a mix of intriguing geology on the upper half of the site, where we were trying to figure out the pieces of the puzzle of how this thing happened, but then going down to the bottom half where the community had been. It was devastating to find a basketball, kids’ shoes and pieces of houses. It was hard being there, walking around knowing what happened.

Are other areas at risk?

JW: Are there other Osos? I just don’t think we know. Our approach to landslide hazard mapping has been piecemeal. Without a single authority charged to look at this, people have applied different standards, and there is no single hazard map. That lack of a larger overseeing entity has resulted in this piecemeal patchwork.

DM: One of the big questions is: How many other areas are there on the west slope of the Cascades where that same combination of river incision into glacial sediment could play out? I’m not aware of any systematic effort to go through and survey and look at that.

Do you see any policy responses to Oso?

JW: It’s undoubtedly had a short-term impact. The question that remains is what the shelf life is of Oso in terms of whether it will result in any meaningful changes down the road for new programs, or funding for landslide hazards. I can be pessimistic. It’s the 10-year anniversary of the La Conchita landslide. Three children were living there in 2005, many of them were killed, and now it’s estimated that 30 children are living there.

DM: We’ve had communities moving farther up into the mountains, not just in this state, but all around the country. If you take a landside like Oso and it happens in a wilderness area, it’s a geological oddity. If it happens in a subdivision, it’s an absolute catastrophe. […] The funding for our state’s landslide program is for one half-time employee, and has been for some time. The SR530 commission recommended expanding the geological hazard and risk mapping in Washington state, and explicitly in our recommendation was to include the potential landslide zones and run-out zones. That bill is now advancing through the state legislature.

What is next? What would you like to see?

JW: Direct federal expenditures from Oso have been over $120 million. The cost to implement a landslide mapping program could be a fraction of that. With the availability of Lidar and the 3D Elevation Program that would do it for the entire U.S., it’s now within our grasp to do hazard mapping in a cost-effective manner.

DM: For over the past decade, the annual funding for the USGS landslide program has been roughly the cost of sending two people to Afghanistan for a year. Yet what puts Americans in more harm, more directly, in more days of the year? It seems to me that when we think about where we are spending our money we should consider how we are not making it a priority to protect people at home.

Any closing thoughts?

JW: Over the last year you can’t help but be introspective about whether all the work you’re doing is, in the end, doing anything to reduce the occurrence of Oso-type events. One of the things that’s become much more apparent to me is just the importance of making sure the science doesn’t die on the vine. We need to be making sure it reaches the public and that the products of our work are understandable to the public.

DM: That Lidar data had been sitting around since 2003, for more than a decade. If we have great data and great techniques to analyze it, but if no one’s actually using that to go look systematically at the places where people may be in harm’s way and then conveying that information to the general public, then we build in a gulf between the state of knowledge and the state of practice. A key challenge is to close the gap between what we know how to do as a field, and what’s being done on the applied end, outside of the geological research community.

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For more information, contact Wartman at wartman@uw.edu or 206-685-4806 and Montgomery at 206-685-2560 or bigdirt@uw.edu. Note: Wartman is on travel and best reached via email.

Tag(s): College of Engineering • College of the Environment • David Montgomery • Department of Civil & Environmental Engineering • Joseph Wartman

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