In the aftermath of the 2014 Oso landslide, it was clear there were significant gaps in how the state had mapped and prepared for the risk of such a catastrophic event. Many people in the community did not know their homes made them vulnerable to a life-threatening disaster.
As bodies were dug from the caked earth, lawmakers and state environmental planners set in motion plans to prevent such harm from repeating. A new mapping project was launched to meaningfully document Washington’s landslide risk — tools intended to inform the public, local government and emergency planners.
But over a decade later, as a historic atmospheric river inundated Western Washington, the map is still unfinished. Critical projections about human and property risk, and which areas of Washington are most likely to experience landslides, still do not exist for much of the state.
On Sunday, a second atmospheric river is expected to hit the region, which is still reeling from record flooding and evacuation orders for 100,000 people.
“It is a knowledge gap and something we are hoping to address,” Joe Smillie, a spokesperson for the Washington Department of Natural Resources, said Saturday. “It’s funds, time and manpower at the end of the day.”
While experts say Washington has made significant strides in landslide mapping since Oso, mapping tools intended to help people understand the risk where they live — or consider risk before buying a new home — still require the public and local governments to use piecemeal mapping systems.
Since 2016, the Legislature has appropriated at least $23 million for an elaborate geo-mapping portal that, one day, will have mapped not only every landslide that has occurred in Washington (once a landslide has happened, future landslides are more likely) but also the level of susceptibility statewide for a landslide risk.
To do this, the state has conducted extensive lidar mapping, an acronym for light detection and ranging — technology that uses light-pulsing lasers to map the Earth’s shape with precise, three-dimensional detail.
The Department of Natural Resources has so far mapped a third of the state, which includes documenting between 40,000 and 50,000 existing landslides. Only Pierce County and the Columbia River Gorge have been mapped for both existing and future risk.
Some areas, including King County, have done their own mapping work.
“We are doing the best we can,” said Kate Mickelson, who leads the state’s landslide mapping team. “It's an enormous undertaking, and we are ahead of most states.”
Still, DNR officials say the agency does not know when it will finish this work.
“It will take us many, many years based on the amount of landslides and steep terrain and the amount of funding and people I have,” she said Saturday. California is the only state that has surpassed Washington in landslide mapping work, Mickelson said.
But because Washington’s state mapping tool is incomplete, University of Washington landslide engineer Joe Wartman said he believes the best available map — and the one he uses for his research — is a new national susceptibility map published by the U.S. Geological Survey.
For years, the risk of landslides was not given the level of emergency attention or resources as disasters like earthquakes and wildfires. But in 2021, federal legislation directed new emergency planning efforts to landslides, contributing to the USGS mapping tool.
“We have come a long way,” he said.
The national map does not provide the degree of granular detail the state map is undertaking but provides a cohesive picture of where there is hazardous, landslide-prone terrain not only in Washington but across the nation.
What no map does is correlate this perilous geology to the actual human and structural risk for our state, he said.
Those kinds of risk maps “are not available,” Wartman said, but he added that they should be.
“I can only say that we are capable of doing this. … It is entirely something that is scientifically achievable. So why are we not there?” he added.
The question of why, according to the Department of Natural Resources, comes down to time, money and staff, Mickelson said. The state has made significant gains since 2014, Mickelson and other experts agreed. Before Oso, DNR had just one part-time person tasked with landslide work, and now the agency has between six and 12 employees working on mapping and wildfire debris flow monitoring that contribute to landslides. Still, more people and funding would be necessary to accelerate the complex mapping project, she said.
Wartman, however, said granular risk mapping is information that not everybody wants. If a home is identified as being within a clear landslide risk area, it could diminish property value, making it harder to sell or build new developments. Identifying risk could also make the government or developers liable when a landslide occurs.
But without risk mapping, when extreme rainstorms hit, people may not know they may be in harm's way or how to protect themselves, Wartman said, which is what happened at Oso.
“There is a real advantage to knowing you are in a hazard zone,” he said. Critically, he said, it makes people more likely to survive.
When the rain comes, listen for the sound of snapping branches, the crack of the earth or faint rumbling below. Notice the subtle shifting of the ground, how otherwise vertical trees or fence poles now appear askew.
Then, Wartman said, people can know they should leave or move their families to a higher floor, away from an upward-facing slope, where they are more likely to survive.
The type of extreme rainfall Western Washington has seen in the last week — which, after a brief pause on Friday and Saturday, is expected to see a new, albeit smaller storm system begin Sunday — is more likely to result in shallow landslides, rather than the deep-seated unearthing that caused the destruction near Oso.
If this storm had come in March, rather than December, Wartman said, he would have been far more concerned. In the spring, the groundwater swells with snowmelt, and when that is met with a heavy storm event like an atmospheric river, deeper geological shifts can cause an entire hillside to collapse.
Mickelson also urged the public to be alert and use every resource available, from maps to the state’s online home safety guidelines, to stay safe in the coming days, weeks and months.
“We have more rain coming,” she said.
As blue skies temporarily crested over Washington on Saturday, Skagit County officials feared some homes in Concrete might be at risk of a landslide. They called on geologists from the Department of Natural Resources. But when state experts went to reference their own map, Mickelson said, the technology was down.
Mickelson said DNR staff used backup data to re-create the maps needed to help Skagit County. By late afternoon, the online mapping tool appeared to be working again for the public.
Still, in the critical hours since the National Weather Service issued an alert for heightened landslide risk early Friday morning, the mapping technology designed to help people understand whether or not they might be safe had been dark.
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