Re: [Paddlewise] Seiche

Joan Spinner wrote:
> 
> This sounds like a description of what happens in Back Bay at Virginia Beach.
> We were told the winds had blown all of the water out of the north part of
> the bay a week or so before we arrived and that only a couple of days before
> we got there the wind had changed and blown it back in.

Joan, your description fits a variation of "storm surge," a different
phenomenon.  A seiche can be set in motion by wind, landslide, tsunami, tidal
exchange, or any other sizeable disturbance of the surface of the water.  In
bathtub terms, it is "sloshing" tuned to the natural period of slosh of the
tub.  Certain to incur the rath of Mom/Dad when you are small.

> wanewman_at_uswest.net wrote:
> 
> > [snip]it is not at all a rare occurance to have
> > Seiche activity on the Great Lakes.  On any given day you will be able to
> > measure cycles of rising and falling water level over a period of a few
> > hours to half a day or so.

Due, no doubt, to that humongus "baby" sloshing around in the other end of the
lake <G>.

Willard Bascom's Revised edition of *Waves and Beaches* has a lucid treatise on
seiche -- pages 104-111.  Out of print, but probably in the earth science
section of any well-equipped public library.  Seiches triggered by a passing
tsunami can be huge, and have been noted in open bays (Monterey Bay, Los Angeles
Harbor).  In addition, an extremely large undersea earthquake generates a
seismic sea wave that can *travel around the world,* one in the North Pacific
triggering seiches in harbors in the Atlantic (for example).  Thanks to Karen
Hancock for leading me to that factoid a couple months ago. (see: 
http://wwwneic.cr.usgs.gov/neis/eqlists/USA/1964_03_28.html for the rest of the
story on the '64 quake, a piece of which is quoted below)

> This shock generated a tsunami that devasted many towns along the Gulf of
> Alaska, and left serious damage at Alberni and Port Alberni, Canada, along
> the West Coast of the United States (15 killed), and in Hawaii. The maximum
> wave height recorded was 67 meters at Valdez Inlet. Seiche action in rivers,
> lakes, bayous, and protected harbors and waterways along the Gulf Coast of
> Louisiana and Texas caused minor damage. It was also recorded on tide gages
> in Cuba and Puerto Rico. 

-- 
Dave Kruger
Astoria, OR
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