Some new research on the Newmark Displacement Method for earthquake-induced landslides indicates that the method may be on the unconservative side. The Landslide Blog provides a short summary of the paper by Li et al. (2018) that was recently published in the journal Landslides. Their research was based on physical models on a shake table, comparing the results of the model experiments with a Newmark analysis. The paper should be worth a read for geotechnical engineers practicing in seismically active areas. It sounds like some additional study is needed to confirm these results and if they are true, propose different ways of analyzing earthquake-induced landslides.
The Mt. Soledad Landslide in a La Jolla California neighborhood destroyed 3 houses and damaged others and it also shut down Mt. Soledad Road for an entire year after it occurred in October of 2007. Residents blamed the city of San Diego, and 65 homeowners filed suit, claiming that leaking pipes caused the landslide and the City should cover damages.
Last week, a superior court judge ruled in favor of the City of San Diego. So far I have not seen anything indicating if the residents plan to appeal the ruling.
One interesting note regarding the trial, the City released an 8-minute cell phone video taken by a geotechnical engineer or drilling contractor employed by the City that showed the road cracking and buckling just prior to failure. The homeowners used the video to try to make their own case. Click through for a portion of the video and a link to the full one.
Back in March of 2008 there was a landslide that closed SR 87 in between Phoenix, Arizona and Payson. It’s been of great interest to me since it is in my state and affected a highway. I was hoping my firm (NCS Consultants, LLC) might be asked to work on the remediation through our on-call contract but it didn’t happen. Its probably for the best, it sounds like it’s been a troublesome geotechnical engineering problem. Fast forward to last week, and the slide area was in the news again because the slope is still moving and apparently causing some additional deformation of the roadway. (Photo by ADOT)
I had heard about this a while ago through our ADOT contacts, but I make it a policy not to take advantage of my contacts through my day job for GeoPrac.net content (not without permission anyway). So I didn’t want to blog about it until it hit the mainstream media. Last week, the Arizona State Geologist blogged about the SR 87 slide moving again, as did Ken through his AEG Arizona Section blog. It was even covered on one of my favorite blogs, Dave’s Landslide Blog. I finally have a chance to wade through these blog posts and some of the reports and videos to present a summary of the situation, available information and offer my own perspective. (More after the break)