Quote:
Originally Posted by wakamesalad
I predict Millennium will be dismantled within a short time frame from now. Hopefully they can put a nice 800 footer in its place (bolted solidly to bedrock).
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There is very minimal to no bedrock anywhere below downtown San Francisco (unless you drill way way way down). Most of downtown is built on sand, silt or mud, with only a few pockets of harder rock base. Otherwise, the majority of the land is frighteningly susceptible to liquefaction if an earthquake with enough intensity were to strike the area (God-forbid; such a thought terrifies me).
And while designing with seismic issues in mind is required in California, the desired effect is to minimize damage as much as possible in order to protect and ensure the health, safety and welfare of occupants (essentially the same credo for architects in general).
Here is a great resource that shows the soil composition of every part of the Bay Area:
https://earthquake.usgs.gov/regional/nca/soiltype/map/