[Gibbon1]

Yeah really depends one distance and local conditions. And sometime 'micro' local conditions.

Friend of mine that lived in Oakland during the 89 earthquake mentioned seeing a 'line' of damaged buildings that snaked through a neighborhood. One or two houses on a block were wrecked. The houses across the street were also wrecked. Houses next to them were fine. Go the next street over same thing.

He thinks that line followed an old creek bed that developers filled in. So those houses were built on mud overlain with poorly compacted fill. During the earthquake the mud liquefied and sloshed around and the fill settled.

Flip side, friend in the Santa Cruz mountains a couple of miles from the epicenter. His house is built on top of a hard shale outcrop. His house suffered no damage at all.

[DrScump]

The weakness of poor fill was also demonstrated by the collapse of row houses in the Marina district of SF.

One striking effect was the directionality of the damaging waves. Bookcases and such that were perpendicular to the waves from the hypocenter went over; those that were parallel were fine.