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In visiting the San Francisco area I have always been amazed by the concrete dam holding back the waters of San Andreas
Lake. It seems the dam is practically on top of the fault - at most just a couple hundred meters from the surface actual rip line. So, what will happen if an 8.0 quake (or less but still very strong) epicentres at the location? Seems like a stupid location for a concrete dam and lake to me and just askling for catastrophe. Was there any controversy when the dam was built? (Yes, I have read there was an earthen dam in 1906 that survived the quake then but that quake's epicentre was 30 miles away and in any case it seems to me an earthen dam would be more flexible than would be the concrete one).

2007-03-27 08:54:40 · 2 answers · asked by Hank 6 in Science & Mathematics Earth Sciences & Geology

2 answers

The topic is certainly on people's radar screens. One website suggests that catastrophic failure of both the San Andreas and Crystal Springs dams could cause up to 25,000 deaths.http://www.plsinfo.org/healthysmc/6/198.html
The Great San Francisco Earthquake of 1906 caused minor damage to the dam but the tunnel spillway that ran through the San Andreas Fault was ruined. The fault offset approximately 2 m in the locality of the dam during the earthquake.(Manuel Bonilla 1991).
Here's a link to an article in the Palo Alto Daily news about the very question you ask. http://www.paloaltodailynews.com/article/2007-2-1-bil-paul
It quotes a chief of the Field Branch, California Division of the Safety of Dams, expressed confidence in the dam, primarily because it was built with local clay. It also quotes a representative from the Public Utilities Commission suggesting that seismic damage is unlikely to be a dramatic breach, more likely to be a leak, if it occurs.

2007-03-28 15:59:09 · answer #1 · answered by luka d 5 · 0 0

Flooding. We also have at least one freeway right on top of a fault here. A major quake will topple buildings, break pipes, cause liqufaction, landslides, fires, destroy roads, communications, etc. Flooding from tsunamis, broken pipes, broken dams, liquifaction and so forth will be a major problem in a major quake. And yes, there seems to be no logic or foresite in the placement of things in the Bay Area.

2007-03-27 16:05:02 · answer #2 · answered by ? 4 · 0 0

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