Tuesday, August 16, 2005

EARTHQUAKES NOT ALL THE SAME

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By Elaine Meinel Supkis

Yesterday, as usual, I visited IRIS earthquake monitor to see what was going on. The previous week, the Australian plate once again jerked forwards in its long, hard push towards Japan as the continental plate cartwheels across the Pacific plate, devouring the seabed as is moves north.

It is no surprise to see Japan suffering from a fairly large earthquake, like all of them this year, in the north. A 7.2 earthquake is quite substantial but in this case, very few people were hurt due to many factors. One obvious one is that Japan, the land of earthquakes, is built to handle earthquakes unlike many other places. For example, in the last ten years, the places in the world with similar quakes had 20,000+ people die because of the building materials used to make houses. In Iran, an entire town disappeared, killing nearly everyone and the quake was similar in intensity.

The use of mud bricks is very incompatible with earthquakes.

Today's quake didn't produce a tsunami because it was a back and forth quake and not an up and down one with the land either rising suddenly or falling precipitously. There was only one landslide. The Kobe quake was not only greater in magnitude but of the much more dangerous up and down type.

True to predictions, the earth continues to shudder from the side effects of the Great Boxing Day Quake. The energy released by that tear is still not finished expressing itself. It will cause the earth to ring like a bell for a long time. This is why there is always a pause in the 4-6 magnitude quakes that have been steadily shaking for the last year. Only a few times since December has the earth had no mid level quakes at all and each time lasted less than 24 hours and ended always with a 7+ quake. Like the vibrations of a bell as the clapper hits it with each swing, the vibrations cease right before the clapper strikes again.

Japan, like Indonesia or New Zealand or other island/mountain chains, is a landmass created by pressure from plates pushing up the ocean's floor. Pressure is relieved fairly easily. But California, with lower magnitude ratings, gets much greater violence because unlike these chains and much more like the Middle East or where India is striking Asia, there is a great continental landmass resisting the push of the ocean plates so the energy is expended in the up/down shaking rather than side to side. And the shape of the land usually changes violently with each quake. Very seldom does the West Coast get quakes greater than 7.9 but those are real doozies.

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Note in this latest map of California that the San Andreas fault is trembling at the top and the bottom while faults that bisect it in the center are trembling, too, the center itself is ominously quiet. Which means it is frozen and will release with a bang.

California in particular is a problem because it is like the Great Rift Valley of Africa, namely, the continent is being torn off at the edges by lateral movement as well as compression. Due to housing pressures, in California they are stacking taller and taller buildings on increasingly precarious cliffs. Recently, the NYT featured some really nicely designed future coffins perched on a sheer hillside that is in the process of growing upwards in violent jerks, the top of which was filled in over a waste dump and then houses built there, typically, landfills turn to jelly when there are earthquakes. The people at the top have a much greater chance of surviving when their homes inevitably slide downhill. The unfortunate people on the lower slopes will have a terrible time of it, when the quake will happen.

As it shall. This is why building recklessly should have been stopped by the authorities. But anxious to get more tax money and with developers warping the political process via bribes and glad handing, what with people refusing to understand the basics of geology, this is a tragedy that will be inevitable.

It is not like we don't know this will happen, either. The feeling is akin to faith: the belief that it will happen to someone else in another time period. The blessings of today will not end except after one is gone or one sells to another, unfortunate person.

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