5 April 2011

An interesting landslide on Highway 101 in California

Posted by Dave Petley

Thanks to Drew Barber and to Brian Huggett for bringing this one to my attention – and apologies to them for my tardy post!

California has suffered a prolonged period of rainfall in recent weeks, which unsurprisingly has resulted in significant landslide activity.  Of particular note is a slide on Highway 101 in Humboldt County about 8 km to the north of Garberville  that occurred last week.  This image, collected by Felix Omai, shows the landslide rather well:

Note the cars on the lower left for scale.  There are two great galleries of images of the landslide.  First, Felix Omai has a Flikr gallery that has views of the slide from both the ground and the air, including the clean up operation.  Second, Redheaded Blackbelt has a commentary as well, also with some great images (but can I caution that this site takes a counter-culture view that I am not endorsing) here . The latter site also has a very interesting commentary from the perspective of a land owner on another landslide in this area, which is worth a read.

In many ways the most interesting aspect of this landslide is the deformation that it has caused to the roadway.  As the landslide has moved onto the highway the asphalt appears to have effectively delaminated from the sub-base.  The landslide effectively imposes a vertical load and a horizontal compressional force on the surface layers.  The result is a series of fascinating features, as shown in the images below (from here):

Reports suggest
that the landslide has now been cleared, the surface has been resealed and the road reopened.