Quote:
Originally Posted by edale
Wait, what? SF (and all of CA) is more susceptible to earthquakes because it's positioned near several major fault lines. Whether an area is hilly or flat has no bearing on whether it's susceptible to earthquakes. They happen in mountainous areas and flat areas alike. Obviously the east coast has much less seismic activity, even though small earthquakes occasionally do happen. The one that hit Philly and DC a decade or so ago caused considerable damage to the Washington Monument.
|
The soil conditions matter VERY MUCH how intense the shaking is during a quake and fault proximity being equal, the shaking and therefore the damage can go from nearly nothing to severe just because of the soil.
The map I posted above shows this very clearly (as does the historical experience of 1906): With a San Andreas quake such as 1906, there would be minimal shaking and little damage on the bedrock at the top of Mt. Davidson or Telegraph Hill but severe damage in the Marina and Mission Districts, just as there was. While it's not so much a question of hilly or flat, the fact is (and I'm sure was being alluded to) that hilly terrain in coastal California is mostly rock whereas the valleys between are sand or mud or alluvial soil.