Saturday, November 21, 2015

Remote Exploration of Santa Clarita Landslide

Susan alerted me to a landslide in southern California that has closed a road in Santa Clarita. Santa Clarita is in the mountains north of Los Angeles. Landslides should be expected if the weather pattern associated with the El Nino event soaks into the geology of this area.

I decided to explore this slide a bit. The fun of Google earth is tracking down sites like this and getting an idea what is going on. This is particularly good with the availability of newer higher resolution aerials. In the image above from this year one can see an incipient fracture at the top of the road cut where the failure took place. Additional breaks took place almost all the way back to the upper road. This is a deep-seated failure where the ground above the cut had has moved towards the cut as a mass pushing the pavement before it.

Google earth also provides a very good before image in street view:

Google earth street view before landslide

Google earth street view of road cut at slide site

  The cut slope in the street view appears to be alternating silts and clays and maybe some fine sands consistent with lake sediments. A good recipe for landslides. The unit is the Mint Canyon Formation ( and consists of terrestrial lake sediments of mid Miocene age.

Finding the exact stretch of the landslide was greatly aided by these before and after pictures:
photos via laist.

This drone footage also gives a a very good perspective: drone via by dmitry

Putting geology hazard in perspective, Santa Clarita has a lot of hazardous ground:

1 comment:

susan said...

That was quick! Excellent. The last map, showing surficial geology, sure tells the story. That area is almost nothing but earthquake-indexed landslides, liquifaction, and streams. Egads. Thanks for "fleshing" this out. Very cool.