12 October 2009
Updated and corrected: Large rockslide in Naches, Yakima County, Washington State
Posted by Dave Petley
Updated: correct landslide location – thanks to various readers (especially Andrew Giles and Steve in ATL) for helping me to get this right – and apologies for the earlier error.
I have posted an update to this post here.
Various media agencies (e.g. here, here and here) are reporting a large landslide at Naches in Yakima County, Washington State, USA, which has blocked state highway. The Seattle Times has a spectacular photograph:
There is also a rather nice (if a little dramatic) video here.
As can be seen from the above video and picture the slide is large (the news reports suggest half a mile (about 750 m) and large. The slide appears to have come down in good weather.
The landslide appears to have come off this slope (from Google Earth) (this is now the corrected location):
A couple of very quick observations about this:
1. As a couple of commenters have noted, there appears to be a quarry on the right side of the area that has failed.
2. Above the road there appears to be what could be a smaller slump with a large scarp, although the quality of the image is not good enough to tell properly:
See the update to this post here.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
Hi Dave,Actually, I think it's a little farther upriver than what you're showing as the location on Google Earth> I found it on Google maps by going upriver on 410, looking for Nile Rd. and the island in the river. Interesting to note that there appears to be some quarrying in the area of the slide.
Here's a map I've made of the area:http://tinyurl.com/yf7ywpn
Actually, there was a quarry there – and much to the local residents' chagrin, the mining company had just re-initiated extraction in the past couple weeks.
Looks like the slide may have been entirely within a huge talus slope below basalt cliffs. Two nice slide shows from WA DOT and DNR:http://www.flickr.com/photos/wsdot/http://www.flickr.com/photos/wastatednr/One photo has the following caption by DNR, "During the investigation on the landslide mass, ice chunks were visible in the landslide, potentially caused by an ice core effect common in talus slopes in Eastern Washington." It refers to this photo:http://www.flickr.com/photos/wastatednr/4004691961/in/set-72157622570021278/
Deformation extends 1000 feet to the east of perimeter of the slide and continues to move. See http://is.gd/4i1r2: "[On the east side of the landslide a] small hill acting as a buttress from the original movement of the landslide is in danger of failing. Sounds of groaning and deformation of the hillside indicated high amounts of stress within the landslide mass." Photos. The peak of this hill is 620' east of the slump perimeter. A photo of the house located on this peak shows deformation (http://is.gd/4hY8F) and as does a photo of the driveway at a point 970' east of the slump perimeter (http://is.gd/4hYoO)
We lived a the base of the landslide. We lost our home and our pasture that we worked so hard on. We were bought out by the county because they needed the land. We had home owners insurance and flood insurance (the maximum flood insurance you can carry). Neither one of them were going to pay us a dime! But they sure collected their money every month! The flood inusurance is through FEMA and the homeowners is through Counry Companies. Don't think your your home is safe because you buy insurance!!
nice information and awsome pics..thanks for sharing…