A dangerous undersea topography for a tsunami is a seafloor that becomes shallower and shallower, as it allows the waves to build up dramatically -- see the illustration here: http://www.pmel.noaa.gov/pubs/outstand/gonz2088/images/image4.jpg . With an island atop a steep abutment, as with some Pacific atolls, the wave can just pass through, causing no harm. If that weren't the case I would have died in 1964. And the same island, Kwajalein, got through the recent tsunami without damage. Recently I heard that tsunami comes from the word for "harbor wave," because harbors are likely to have shallowing bottoms and a bowl-like structure that funnel the power of the tsunami in. But I have suspect that when one hits a really wide shore it causes damage regardless of the ocean bottom. Thanks, Joe --- On Fri, 3/18/11, erikhansen@thebluezone.net <erikhansen@thebluezone.net> wrote:
From: erikhansen@thebluezone.net <erikhansen@thebluezone.net> Subject: Re: [Utah-astronomy] Japan Earthquake Discussion To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Friday, March 18, 2011, 3:38 PM
Anyone remember the Missouri earthquake? It was an area no one believed was at risk.
Salt Lake is full of houses that are poor in an earthquake, a 9th mag earthquake would ruin Salt Lake City.
BTW, did a little digging about tsunamis, seems the worse scenario is a steep shore line. This concentrates the kinetic energy on the shoreline. The initial event determines the energy contained in the waves.
Incidentally, I am currently working on a rehabilitation, including a
seismic upgrade, on a stone and adobe house in Ephraim. The Japan quake has me thinking more about these issues even more than usual. If you live in an unreinforced masonry home, make sure your will is in order.
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Rodger C. Fry Sent: Friday, March 18, 2011 2:01 PM To: utah-astronomy@mailman.xmission.com Subject: [Utah-astronomy] Japan Earthquake Discussion
This is mildly off topic but does talk about crustal tides and earthquake predictions.
I don't know much about this guy but what he is saying may provide for an interesting discussion.
Time will Tell.
Follow this link:
http://www.youtube.com/watch?v=xQXDt4VdS0E
Rodger Fry
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