This link gives an excellent view of what the insurance industry understands about earthquakes. The full pdf has lots of pretty pictures!
Basically, it is saying that the risk will be lower than thought for tall buildings in California. Yet this report only uses PGA (my most hated bug-a-boo of all!!!), and makes no mention of soil conditions. They also don't mention directivity, or velocity pulses.
So, in other words, the Warren Buffet clan doesn't know squat about earthquakes, and isn't that a wonderful thing....
ps. most high-rises have to be founded on rock, or they will tip over. This makes them generally happy in earthquakes, but they can really fling in a velocity pulse. Buildings up to 10 stories can be founded on mud, with a raft foundation, and are something to be avoided.