Ques re: Richmond District in SF
 

Hi all . I just recently moved to SF and am living in the outer richmond area. I know that certain areas in the city w/ landfill are considered unstable in the event of an earthquake. I know the Marina is one such neighborhood. What other areas of the city are made up of this landfill?..from what I've gathered, the Richmond areas used to be sand dunes in the past..forgive my ignorance but is this considered unstable too?..thank you in advance

You're correct - it was sand dunes - not landfill. I don't think there was any dammage out there during the '89 quake.

Stu Dudley

The Marina and many parts of SF bordering on the Bay are built on landfill (mudflats were filled in to build upon) and are therefore subject to something called liquefaction during earthquakes i.e it acts like shaking jello. As Stu noted the Richmond is not built on landfill, but sand dunes, so there is not the same effect. If you are interested here is a map that shows liquefaction areas in the northern parts of SF.
http://z.about.com/d/geology/1/0/F/3...azmapnorth.jpg

Sand dunes are not as stable as bedrock, even if more stable than landfill.

Thanks!

No place in SF will 100% safe when the Big One hits--but most of us live in denial. As newer residents have never experienced a significant quake, it is easy to either be not aware of the risks or in some cases be overly concerned; those of us who have been here longer, just accept it as a risk of living here--maybe that shapes our collective character. Anyway, yes the Richmond is not stable as areas that are built on bedrock--but if you look at the map, some parts of those bedrock hills are subject to slides.

There is no 100% guarantee that any place will be safer than the other. Factors other than geological components can come into play, such as structural soundness of the building you might be in.

I have friends who own a house in the Sunset which was built in 1948. They've had their foundations checked recently prior to remodeling, and no damage was found, although this house really rocked and rolled in the '89 quake - not to mention all the other, less famous shakers it's stood through.

In addition to landfill, areas bordering former lakes and marshes are really subject to damage. The blocks around 7th and Lincoln sustained damage in '89 that was not seen just a few blocks away. Why? Because the ball park across from Lincoln Way sits in a little depression which was part of a small lake till the building of Golden Gate Park.

I grew up in San Francisco and received regular earthquake safety drills in public school, just like fire drills. The safety tips hammered into my 7-year-old brain really stayed with me. No matter what neighborhood I'll be in during the Big One, I WON'T go running outside willy-nilly and I will brace myself in a doorway away from windows.

We lived in Jordan Park during the Loma Prieta Quake. This area has 3 spring fed lakes and many homes were damaged enough to be condemned. We lost an enormous amount of personal items which seemed meaningless at the time given others loss of life and limb.

Bernal Hgts is bedrock I think.