The slide happened as a result of heavy rains (surprise). City officials said that the slide happened on private property, and the owners would be responsible for stabilizing the hillside. The San Francisco Chronicle has a good article with photos and figures.
According to CNN, and you can probably see it in some of the photos, a portion of the hillside was already stabilized in 2000, apparently with soil nails or possibly some kind of Tecco type system. The property owners effected by this slide had the opportunity to contribute to the pool of funds used for the stabilization, but opted out.
Here is a video from YouTube showing some of the work to stabilize the slide at the base of the condos at the top of the hill and the preparation for excavating a pit or shaft for the geologists and geotechs to check out the slope.
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Also, check out some additional video at the local CBS affiliate’s website.