

Japan tsunami was at least 23-metres high - erikstarck
http://www.abs-cbnnews.com/global-filipino/world/03/18/11/japan-tsunami-was-least-23-metres-high-report

======
anigbrowl
That's going to be rather awkward for California's coastal nuclear plants,
which IIRC are about 80 feet above sea level. While I'm generally pro-nuclear,
I've always doubted the wisdom of siting plants in earthquake-prone areas.
Although the San Andreas fault in southern California is not thought to be
capable of generating such a large quake, the Cascadia fault (off the coast of
Washington state) probably is.

Plus, the fact that they're operated by PG&E fails to fill me with confidence
- the company has a mediocre public safety record, and both plants were beset
with construction problems: in Diablo Canyon the seismic supports for one
reactor were built backwards, while one of the reactors at the San Onofre
plant was also installed backwards. both plants are said to be safe for
anything up to a magnitude 7 quake right next to the reactor, but hearings
that were due next month to extend operating lifetime have just been postponed
pending resolution of the situation in Japan.

The historically unusual size of the quakes at other locations around the
'ring of fire' (Chile, NZ, and now Japan) is naturally worrying to disaster
planners in California, and the problems at Fukushima demonstrate the
potential severity of a cascading failure. The 50 mile safety radius
recommended by USG would include ~7.5 million people if applied to the San
Onofre plant, which is midway between Los Angeles and San Diego, and right
next to southern California's major freeway. Diablo Canyon is about 60 miles
north of LA, albeit in a hilly area that is unlikely to be affected by a
tsunami.

~~~
ChuckMcM
It is important to understand that California earthquakes are extremely
unlikely to generate tsunamis. That is because a tsunami (or tidal wave) is
generated by a _subduction_ fault where one plate is sliding over or under the
other. When tension is released there is a sudden change in relative altitude
on either side of the fault, that if it occurs under water results in lifting
up (or dropping) a large mass of water.

California has _strike/slip_ faults, that is faults where two plates are
moving past each other. They tend to create large horizontal dislocations
along their fault rather than vertical dislocations. This does not result in
massive water movement.

That isn't to say that its not possible, at some level all things are
possible. But locally generated tidal waves (from a California fault) are even
more rare than earthquakes of magnitude 8 or higher.

That being said, two things disaster planners can take away from the Japanese
experience are; Storing more spent fuel in the pond than the pond is designed
to hold is a huge deal, it should be on the inspection list, there should be
mandatory fines if discovered and an immediate shutdown until the situation is
corrected, and additional backup power options should be available, with
infrastructure immune transport (aka helicopters), within a couple of hours.

~~~
anigbrowl
The Cascadia fault is a subduction fault, and this was the reason I mentioned
in the context of risks facing commercial nuclear plants in California (there
are none operating in Washington or Oregon).

<http://en.wikipedia.org/wiki/Cascadia_fault>
<http://walrus.wr.usgs.gov/tsunami/research1.html>

edit: I ought properly to be calling it the 'Cascadia subduction zone' rather
than a fault, because it spans several named faults where the North American
plate meets different pacific plates.

~~~
ChuckMcM
You will note I didn't mention that Oregon and Washington :-). If you look at
the USGS analysis [1] of the tsunami risk it does not extend below the western
most part of California (Eureka/Fortuna area). This is a bit of fortunate
geologic structure on the part of California. You might also note that there
are no US nuclear power plants near the coast between Eureka and the southern
border of Canada [2] so for some definition of risk avoidance, no one has
built reactors there.

Point being, in California at least, there is a very very small chance that
one of our reactor's disaster plans will be challenged by a combination 9.0
earthquake and a 30' tsunami.

[1] <http://pubs.usgs.gov/pp/pp1661b/>

[2]
[http://en.wikipedia.org/wiki/File:NRC_regions_and_plant_loca...](http://en.wikipedia.org/wiki/File:NRC_regions_and_plant_locations_2008.jpg)

