🚀 go-pugleaf

Ralph Finch (rfinch@toe.CS.Berkeley.EDU) wrote:
: In article <4psipd$p1c@mark.ucdavis.edu> ez059768@rocky.ucdavis.edu (Brett Valle) writes:
: 
:    OK, even though your defeating the whole purpose of Doolittle's
:    "Flood Control Dam," I'll argue with your three points.  (1)
:    protect property - the dam lies on an active fault system that has
:    a significant chance of releasing in the next 50-100 years
: 
: Now here's a crock.  Earthquake probability making, like hydrology, is
: basically a statistical, not deterministic, science.  That means you
: need data, lots of it, to determine return intervals.  And you just
: don't have that in Auburn.
: 
:    of the USGS believe is quite possible), downtown Sacramento will
:    sit in 40 feet of water six hours after the rupture.
: 
: _If_ the dam happens to be brim full when the earthquake
: happens. Flooding w/o the dam is much more likely.
: 
Mr. Finch,
I hope you know of the Oroville earthquake in 1975 that just so happens 
to be the exact system the Auburn Dam will sit on.  Also, studies about 
large dams have shown STATISTICALLY to speed up the rate of recurrence 
faults under large reservoirs.  Both the scientists and engineers that 
have studied the underlying geology agree that displacement will take 
place at the dam site, they just do not agree on how much.  The whole 
problem with Auburn is that the data for either side is ambiguous, so 
taking such a serious gamble with such an expensive dam does not show 
good judgment.  
We do know that Auburn lies near an active fault, and the reservior would 
be in prime habitat for reservoir-induced seismicity.  Studies of late 
have shown significant evidence that large, deep reservoirs with radical 
changes in lake level (such as the case with Auburn) increase both 
frequency and magnitude of earthquakes.  Your theory that the dam would 
not be "full to the brim" is somewhat correct; it would likely be just 
below the brim.  With RIS, a reservoir can fill completely without any 
noticable change in tectonic activity.  This achieves a new stabilization 
for the fault; the fault remains secure as long as the pressure is 
constant.  When the reservoir starts to drop, however, the loss of 
pressure on the fault causes it slide.  "Lots of data" are present 
showing the relationship, but you still probably think the evidence is a 
"crock" considering your unwillingness to accept anything said by people 
opposed to the dam.
Brett
P.S. In regards to the vote mentioned in an earlier followup, yes a few 
years ago the dam unanimously passed.  Recently, however, a poll of 
citizens in Auburn showed 89% of them to be opposed to the dam.  A vote 
in Sacramento (where it seems like all the politicians are dead set on 
getting the dam passed) showed the dam barely passing 7-6.  On radio 
shows and newspaper clippings, about 4 out of 5 people disapproved of the 
dam.  Check your facts before making ignorant statements.