A BIG 'N! Dumb old me.
I've always thought tidal waves had something to do with the ocean's tides. Simply “a big 'un” sweeping in over land. Now, I find they don't fit that simplified definition at all, in spite of the fact that I was not the only dummy on the beach to think it was accurate. I find a great many other people still think so.
That is especially true of those of us who now live inland and at high elevations and consider tidal waves a problem for low country dwellers, dike builders, sand-pounders and flat landers alone. They have another think coming if they have a lake nearby.
I've learned a lot recently. I now know that tidal waves, so called by some for reasons now best forgotten, who made the same assumption I did. They are really caused by earthquake activities of several sorts.
And don' t get all too sure of yourself by saying how few earthquakes we have. Statistics show we have several thousand quakes per day, not big ones, mind you, but ”quakes”, none the less. The are the result of chunks and piece of our planet rearranging themselves below below the crust of top of which we live. The natural result of such shifts is some shaking and rearrangements of contours and placement of crust materials.
<> Since more surface of our Earth is covered with water than visible land it is
logical that many such quakes will occur in the
huge mountain ranges, canyons and depths of the sea - in some places as deep as about six miles. The water above such lands exerts tremendous pressure on the all below and when the base moves, so does the water above it. If the underlying surface rises , for instance, from internal volcanic eruptions the water is force upward and forms a wall of water high in the air. It rushes in all directions as a high wave of water often at speeds of over two hundred miles per hour depending on the velocity of the upward surge.
That, then, is what we call a “tidal wave”. If the undersea rupture causes an area of the bottom to fall, the covering of water follows it and leaves a high wall of water above which rushed off in the direction of least resistance. That, too, become a tidal wave and it may seek and find a landfall far off and at high speed.
There are countless example of such monstrous waves striking coastal area often with great loss of human life and of geographic features. Entire landscapes have been changed radically by such attacks and often in the most unlikely places. No area is completely immune, it seem, although there are some which have a combination of conditions which incite volcanic activity and, hence, a increased chances of such upheavals. There is, probably, no better way for any of us to convince ourselves of the indomitable power of Nature than to study the effects of water on the site where we happen to live to live. It is not a localized thing, either. I have been surprised to learn just recently that geologists working in the Grand Canyon have come upon sediment materials found only in the Appalachain Mountains here in the Eastern section of the continent.
Read the facts about such events as the explosion of Santorini around at about 1500 B.C. to see how repeated waves hundreds of feet high swept over Crete and other isles, roared well up the Egyptian Delta, plummeted Syria and desolated much of the known world at that time and changing the coastlines dramatically. Or you can turn closer to our time in 1893 when Krakatowa let loose in Java. High waves are not uncommon in some areas.. .as much as thirty feet on the north side of the Hawaiian islands and predictable and fine setting for water sports enthusiasts. There is, however, no sporting element if a would be there an Alaskan earthquake that could send a real wall of water southward. The Galveston, Texas disaster in l903 was a terrifying example with hundred foot waves moving at a hundred miles an hour.
Don't underestimate tidal waves.
A.L.M. July 22, 2004 [c711wds]
