There was once a time when an event such as the landslide that struck in Oso, Washington, would have been called an act of God. But as we’ve become more savvy about the manmade triggers of many disasters, that’s no longer so.
Nowadays, it’s just as routine to look for the role humans play in hazards as it is to look to nature. So, are humans at least partly responsible for the Oso disaster?
After weeks of rainfall sent a massive debris flow plummeting down slope to bury a mile-wide swath of the valley below, everyone focused on the tragedy and the search to find the missing. Within a week, however, the Seattle Times published an analysis that damned state regulators for not protecting land near the slide site from ecologically unsound logging practices.
The analysis examined a 1997 report by geomorphologist Daniel Miller that delineated where ground water could leach into the slope and create a landslide risk. Despite lauding the report as state of the art and using it to issue logging restrictions, the Washington State Department of Natural Resources later approved clear cutting (a practice that removes all or most trees from an area) on about five acres that should have been protected, according to the Seattle Times report. Removing trees, which absorb rainfall, can lead to excess water seepage and destabilize the landscape.
“We did the work,” Miller told the Times. “It was cited in the prescriptions as what you should do. And it appears from your comparison of the maps that it didn’t get done. I suspect it just got lost in the shuffle somewhere.”
While the oversight was significant and could have contributed to the landslide danger, the public revelation may have been premature for a community built on logging and still reeling from the disaster. Indeed, many of those searching for bodies in the mud are loggers.
“They don't need to hear ... that,” resident Peter Brandt told CNN on the topic of logging and landslides. “They need to hear thank you and God bless you.”
Further, scientists can’t yet be sure—and may never be—of exactly what role logging played in the disaster. The area has a long history of both logging and landslides, and while there are widely acknowledged links between the logging industry and shallow debris flows, the Oso slide was deep.
“I can't even put my finger on a really clear, defensible, definitive study that says ‘Yes, logging matters for deep-seated landslides,’” Josh Roering, a University of Oregon, Eugene expert on logging and landslides, told National Geographic News.
Even though the timing and tenuous connection of the Seattle Times analysis might be unfortunate, probing for possible manmade causes is helpful. The shallow landslides that can be linked to logging could be just as damaging on a smaller scale, and some residents may be unaware of the danger hanging over their heads.
“Nobody told any of us,” 63-year-old Robin Youngblood, a native of the area and survivor of the slide, told CNN. “This is criminal, as far as I'm concerned.”
Furthermore, disaster experts have long known that it takes these sort of epic-proportion disasters to get the public to take notice and implement change. In that sense, looking to manmade causes is absolutely constructive and necessary, as Miller pointed out in a recent editorial.
“Mapping hazards is not a national priority,” he wrote. “Yet it seems that, if my smartphone can tell me how to drive to the nearest coffee shop, it should be able to tell me what's known about the hazards where I'm standing. We have the technology; we need the public interest to drive the required investment.”