Because of soil issues, the Transbay Terminal (Salesforce) builders had to anchor the foundations in the bedrock, which is unfortunately deep under layers of landfill and soft sand. But this fill and sand is exactly what will get liquified during a big one, so they didn't have much choice.
But what's weird, IMO, is that some of the shorter highrises like the Millennium Tower were approved to be built not anchored, but on pylons floating in the soil layer:
I mean, sure, as long as things are stable, the weight of the building will keep it in place. But I don't think anyone knows how the soft layer underneath most of SOMA will behave, when a big earthquake comes. People know it will undergo liquification, but by how much, and what will it do to buildings on "floating" foundations, that's not certain...
You assume, based on the journalists' innuendo, that friction piles are per se not seismically safe. That's wrong. Friction piles are well studied and used for tall towers in seismic zones all around the world, including Japan.
That the Millennium Tower is sinking asymmetrically doesn't necessarily mean the design was flawed, even in a high-risk earthquake zone. It could be flawed, but the very fact that it's sinking doesn't tell us that. It could merely be that out of the hundreds of towers constructed globally each year, Millennium Tower was the unlucky outlier which defied the otherwise carefully weighed odds.
Even if that isn't the case, the Millennium Tower is literally across the road[1] and could fall in the wrong direction considering "Millennium Tower has sunk almost a foot and a half and is leaning 14 inches toward neighboring high rises"
Is 14" of lean a lot on a high rise? Certainly that is a small fraction of a degree of total lean.
The sinking does seem like a concern and is no doubt related. It seems like someone underestimated how much foundation work would be needed on that building.
How does the front door work? Do they have steps down into the lobby now?
A really long way. The center of mass has to move past the edge of the base for something to fall over. I can't find how big the Millennium Tower is to work it out, but I'd guess at least 30 feet.
I this "lean" is measured at the top, and the buildings weight is equally distributed from top to bottom (i.e. its centre of gravity is right in the middle) it can lean half its radius until the CoG is no longer above its support and it should topple.
That's very rough of course. Many bad things could happen much earlier, such as unexpected forces causing structural damage.
Note also that the WTC didn't exactly "fall over". It collapsed on itself.
Here’s an article about what they did. (Skip the fluff in first third, it does get down to details later.)
http://www.structuremag.org/?p=11635