UNION GAP, Wash. -- The fissure was first spotted in October on Rattlesnake Ridge in south central Washington state, overlooking Interstate 82 and the Yakima River.
Since then, a 20-acre chunk of mountainside -- roughly 4 million cubic yards of rock, enough to fill 25 football stadiums to the top of the bleachers, eight stories up -- has been sliding downhill. Geologists can measure its current speed -- about 2 1/2 inches a day -- but they cannot say for certain when, or if, it might accelerate into a catastrophe. And they are powerless to stop it.
"The mountain is moving, and at some point this slide will happen -- it's just a matter of when," said Arlene Fisher-Maurer, the city manager in Union Gap, just north of the ridge.
"So we wait and see and prepare," said Fisher-Maurer, who keeps a police scanner on her desk for alerts. "The preparation has been key, and I think it's going to do us well."
The usual course of events when nature comes unhinged is for researchers and responders to look back in time, trying to understand what happened, as they assess and address the damage done. Here it is the opposite: They are looking forward in time at a disaster in waiting, in which all is still potential and nothing is certain.
The worst-case scenarios -- considered unlikely but possible -- have the slide breaking loose suddenly and roaring down toward the Yakima River, blocking the channel and flooding the valley, or burying the interstate that runs along the river, carrying 30,000 vehicles a day. Either would mean big trouble for a rich agricultural district where apples and hops are king, about a 2 1/2 hour drive from Seattle.
By giving scientists, officials and the people who live nearby so much time to stew over what could be happening, the slow-motion nature of the slide -- at least so far -- has already created tensions.
About 75 people have been evacuated from nearby houses that may or may not ever be damaged. The local road at the foot of the hillside has been closed. Irrigation canal operators stand ready to open dams and take water from the river if it is blocked by a rock slide. Alternate highway routes have been mapped out, in case the interstate becomes impassable.
Current projections, based on dozens of motion sensors that have been installed on the ridge, suggest that the collapse is most likely to happen sometime in late February.
"In a lot of disasters, you don't have as much warning as months -- hardly any," said Jeff Emmons, the emergency management director for Yakima County. "It's a unique thing."
Emmons says he gets updates every day from state geologists and other experts about the odds and percentage predictions of the slide's likely path. And then he tosses those odds out the window.
"I can't rely on percentages, because in my world, 1 percent is still a chance," he said. "I don't feel comfortable banking on a percent number for public safety, or life safety. In my view, everything is possible."
The uncertainty has made life harder for the people who have been evacuated, like Antonio Martinez, 42, a construction worker. He and his wife, Irma, and their four children got out last month, along with all their dogs, chickens and turkeys. He said he would like to return, but he wonders whether he would feel safe there, even if the slide comes down a different way and spares his house.
"I love my place, I raised my kids there, I've spent 15 years of my life there," he said in the hotel room where his family is staying. Their animals have been taken in for safekeeping and care by neighbors who have not evacuated.
"But if it's not safe, I won't come back," he said. "I'm kind of old, but I'm still in love with my life."
Perhaps paradoxically, one of Emmons' fears is that the mountain will go on creeping, molasses-style, for so long that people grow tired of worrying about it and stop paying attention to advisories and alerts, putting them at greater risk when the break does come.
"If this goes on for months, it's going to become old news," he said.
A Section on 01/23/2018