The tragedy that struck the town of Oso earlier this year can serve as a teaching tool for saving lives in the future.
The March 22 landslide that came loose from a hill, crossed a highway and a river, and buried a housing development has forever altered countless lives in northern Washington’s Snohomish County. The end result? Some 10 million cubic yards of dirt spreading over a vast debris field. The toll? A count of 43 fatalities, making it the deadliest slide in U.S. history.
And while the pain and devastation continue to linger, a pair of developments last week demonstrate the learning opportunity provided by the disaster. A report from the Geotechnical Extreme Events Reconnaissance Association has explored some of the scientific causes of the slide, while a committee formed by Gov. Jay Inslee and Snohomish County officials will examine the response to the event.
In both cases, the overriding goal is the same: Preventing and minimizing future disasters.
First comes prevention, which demonstrates the potential usefulness of the GEER report. In looking at geological factors, a team of six scientists and engineers found that previous slope failures set the stage for Oso. A succession of slides dating back to the 1930s, with the most recent being in 2006, left a mass of soil piled against the base of the hill. Combined with extreme rainfall in March, that dirt eventually gave way. “That very clearly played an important role in triggering the event,” University of Washington engineer Joseph Wartman, co-leader of the study, told The Seattle Times.
What remains unanswered, however, is the question of how logging practices contributed. “What it does show is that these are naturally very unstable slopes,” said UW geomorphologist David Montgomery. “And where would you expect the effects of forest practices — if there are any — to be most manifest? On the least stable slopes.” As development continues to encroach upon previously untouched wilderness, further investigation will be required.
The second part of preventing a repeat of the Oso devastation is examining the response to the slide. That will be the purpose of a 12-member commission convened by the governor and local officials.
Helmed by business leader Kathy Lombardo, a trained geologist and former staff member of the Bill and Melinda Gates Foundation, the committee was constructed in an effort to avoid political partisanship. That will be crucial to deriving any meaningful conclusions, the kind that can effectively inform legislative action or lead to improvements in how governments react to disasters. Inslee properly stressed that the commission’s purpose is not to assign blame for the slide but to generate improvements.
Either way, one aspect of the fallout from Oso should be an examination of how jurisdictions approve housing developments. As the mudslide demonstrates — along with the recent Carlton Complex of wildfires, which burned an estimated 300 homes in northern Washington — there are certain areas that should be left free from development. As Portland State University geologist Scott Burns told The Seattle Times, “We should approach landslides like we do floods and say, ‘There’s a risk here, like the hundred-year flood plain.’ “
Ideally, that will be the legacy of Oso. The extent of the devastation, with debris extending one mile from the hilltop and scores being killed in its wake, remains difficult to comprehend. Failing to learn from the experience would merely compound the tragedy.