Isn't this a particularly vulnerable area? When I lived in California in the early 80s and again in the early 90s the coastal area of San Pedro, along with Laguna Hills, CA 1 near Big Sur, and Malibu had quite a few bad slides (closing the coastal highways for a lengthy period of time and damaging more than a few pricey homes).
Mark A. Lewack
Emergency Actions Coordinator
Facilities, Security, and Contracting
U.S. Office of Personnel Management
1900 E Street NW, Room 1300
Washington, DC 20415
Office: 202-606-5415
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From: californiadisasters@yahoogroups.com [mailto:californiadisasters@yahoogroups.com] On Behalf Of Lin Kerns
Sent: Monday, November 21, 2011 12:41 PM
To: Geology2; CaliforniaDisasters
Subject: [californiadisasters] Interesting coastal landslide in San Pedro, California
5 November 2011
Interesting coastal landslide in San Pedro, California
Posted by dr-dave
News today of an ongoing landslide affecting San Pedro in California. This slide, which has developed over the last few weeks, has closed the coast road. Real concern about the site emerged a couple of weeks ago; since then the problem has become far worse. At the moment I can't find a decent still image of the site, but this still from this news report gives an idea of the magnitude of the problem (NB this is definitely not a sinkhole – it is a landslide):
Fortunately, it is only the road and utility lines that are threatened.
The site is well-covered by Google Earth imagery. This is the most recent perspective view from March this year:
Compare that with an image from two years ago:
There has been a very noticeable loss of material on the right side(from this view) of the landslide, which shows the development of a progressive failure. I would anticipate that the loss of this buttress has destabilised the remainder of the slope. Thus, at least on first inspection, this just looks to be a natural failure caused by erosion by the sea. Where the road is so close to the cliff edge, and materials are weak, this is to be expected.
Repair of such a section would be very expensive and environmentally damaging as a large toe support will be needed, with a large volume of fill behind. Relocating the road inland looks to be the sensible option, if that is possible
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