Geologists monitoring the 20-acre landslide on Yakima’s Rattlesnake Ridge say the slide is slowing down.
Earlier this year the landslide was moving about 1.7 feet per week, which is just under three inches a day. A recent report from the Pacific Northwest Seismic Network (PNSN) shows the slide is now moving about 1.2 feet per week at its fastest points, and less than a foot each week at the slower points.
The massive crack in along Rattlesnake Ridge near Union Gap originally appeared in October of 2017. The PNSN has been watching the slow-moving landslide and installed monitors to track the slide in January.
There is still a chance the Rattlesnake Ridge landslide will speed up and “fail catastrophically,” but that event is looking less likely as the slide slows down.
Steve Malone, a seismologist with PNSN monitoring Rattlesnake Ridge, believes the slide will continue to slow until it stops altogether. Malone said the exact time the landslide will stop is currently hard to tell.
The landslide can be clearly seen by anyone driving along I-82 in Union Gap.
The Washington Department of Natural Resources (DNR) initially predicted a full slide would occur in March, prompting Yakima County and the city of Union Gap to declare a disaster. The DNR dropped their timeline for a full slide in mid-March.