The ones in SOMA and the new UCSF campus are all built on land reclaimed from the bay. In other words, rubble. When an earthquake hits, they are within a liquifaction zone. This is a zone that during earthquakes, behaves a little like a liquid.

The buildings they are putting up there, however, have foundations drilled down so deep, they are well in to the bedrock below. They aren't going to come down.

I don't know how I feel about being on the street if that happens, though.