Old Patriot's Pen

Personal pontifications of an old geezer born 200 years too late.

NOTE The views I express on this site are mine and mine alone. Nothing I say should be construed as being "official" or the views of any group, whether I've been a member of that group or not. The advertisings on this page are from Google, and do not constitute an endorsement on my part.

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Location: Colorado Springs, Colorado, United States

I've been everywhere That was the title of a hit country-and-western song from the late 1950's, originally sung by Hank Snow, and made famous by Johnny Cash. I resemble that! My 26-year career in the Air Force took me to more than sixty nations on five continents - sometimes only for a few minutes, other times for as long as four years at a time. In all that travel, I also managed to find the perfect partner, help rear three children, earn more than 200 hours of college credit, write more than 3000 reports, papers, documents, pamphlets, and even a handful of novels, take about 10,000 photographs, and met a huge crowd of interesting people. I use this weblog and my personal website here to document my life, and discuss my views on subjects I find interesting.

Monday, March 28, 2005

Why No Tsunami This Time?

I'm not a geologist or a geophysicist, but I've done more than a little studying in that field, and have a little practical experience. I think the major reason there was no tsunami from the latest major earthquake near Sumatra is because of the location where the quake took place, and the depth at which it happened.

The original earthquake took place along the edge of a major ocean trench, and was a result of the Indus plate slipping under the Sunda (or Burma - I can't remember which) plate. This kind of fault is sometimes called a plunging fault. What happens when a portion of one plate slips under another is a tremendous release of energy, and usually some movement along either or both plate boundaries. The upper plate is usually shoved up even higher, and the lower plate is shoved down (See Figure 1). Whenever the land moves up and down, and there is contact with water, the energy of the land's movement is transferred to the water, and you have one or more tsunami waves.

This latest earthquake, based upon where it's located and its depth, was more likely a simple horizontal strike, or one where the two plates slid on top of one another. It also appears that there was little up/down motion, which is what causes tsunamis.


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