07 January 2010

Sanborn's and the Quake






Sanborn's is a large department store chain in México City. The store downtown features a grand restaurant in the middle, an obviously popular place among the office workers for late breakfast and lunch.





The restaurant in Sanborn's is just another great restaurant in this city.




The real reason that I post an entry about Sanborn's is portrayed in these photos. Click on them. In the background you will see wire fencing material wrapped around that column. The column along with one of the other columns was damaged in the 1985 earthquake. The wire is there to prevent chunks of stone from breaking loose and falling out into the dining area. You can also see wire wrapped around the column in the far background of this photo:




The earthquake in México City in 1985 is interesting in many respects. I wish to mention just a couple here. First, México City does not lie on or near a fault line as our Pacific coast cities sit in proximity to the San Andreas Fault. There is no fault line anywhere near México City. The slippage that occurred in 1985 took place on a fault line clear over off the Pacific coast of México.

The problem arose from the fact that México City is built on that lake bed. When the tremors reached that area, the lake bed simply “liquefied,” which enhanced the tremors. That is not a very scientific explanation, but perhaps you get the idea.

Moreover, there was a weird congruity between the resonance of the tremors and the natural resonance of the lake bed and the natural resonance of the taller buildings in México City. The frequencies coincided. The result was that the old colonial buildings of no more than two or three stories survived with some little damage. However, the destruction among the taller, modern buildings in the city was enormous.

The quake was felt as far away as Los Angeles and Houston. Approximately 10,000 people died in the México City earthquake of 1985.



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