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Anonimo

Apr 27, 2009, 1:09 PM

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Ahora, encima de todo

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An earthquake today in Mexico City.
http://www.eluniversal.com.mx/notas/593976.html

Saludos,
Anonimo



Rolly


Apr 27, 2009, 1:27 PM

Post #2 of 9 (2296 views)

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Re: [Anonimo] Ahora, encima de todo

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The epicenter was near Acapulco, not Mexico City, according to the US Geological Survey. The shaking was felt in DF about 145 miles away.

More details here.

Rolly Pirate


La Isla


Apr 27, 2009, 2:19 PM

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Re: [Rolly] Ahora, encima de todo

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The epicenter was near Acapulco, not Mexico City, according to the US Geological Survey. The shaking was felt in DF about 145 miles away.

More details here.


This was a piece of cake compared to all the museums being closed in the D.F.! I was downtown when it happened and didn't see or feel a thing.


Anonimo

Apr 28, 2009, 1:24 AM

Post #4 of 9 (2236 views)

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Re: [La Isla] Ahora, encima de todo

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I wrote to an amiga in DF. She said that they had not noticed any damages in their area of the city. She lives in Colonia Roma Sur, which had terrible damage in the September, 1985 sismo.

Saludos,
Anonimo


Papirex


Apr 28, 2009, 10:00 AM

Post #5 of 9 (2190 views)

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Re: [Anonimo] Ahora, encima de todo

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We were aware of the quake here in Cuernavaca yesterday, although we did not feel it. My wife noticed that the glass doors on our entertainment center were trembling. When we looked at it we noticed the reflections on the glass were jumping all over the place, but we didn't feel anything here, the house was not moving at all.


We didn't get any phone calls from our family in México City, and someone always calls us whenever anything unusual happens there, snow, a particularly cold spell, etc. My suegra's apartment was destroyed in the 1985 quake there. I was raised in California which has a lot of quakes, and I spent the last half of my life in Alaska which is the most seismically active state in The US, earthquakes are at least a weekly event up there, so earthquakes are not unusual or terrifying for me.


Many people do not understand how the Richter scale is set to measure the severity of earthquakes. Every number indicates a doubling of the severity. A rating of 5 is fairly severe, a rating of 5.1 indicates a doubling of the severity, 5.2 indicates a doubling of a 5.1 quake, etc.


The second most severe earthquake ever recorded was the 1964 “Good Friday” earthquake in Anchorage, Alaska. The tsunami caused by that quake traveled across The Gulf of Alaska, when it reached Canada it killed a few people there, it then traveled down the west coast, the last people killed by it were a couple of fishermen in their boat in the bay in Eureka, California. That tsunami was only about two feet high when it passed San Francisco.


The most severe earthquake ever recorded occurred in Chile a few decades earlier. The tsunami from that quake traveled across The Pacific Ocean and killed some people in Japan.


We were not in México City when the 1985 quake occurred, but we went there as soon as travel to the city was again allowed. The damage was horrendous. There were collapsed buildings with bodies inside them all over the city. There was a collapsed medical clinic just a few blocks from my suegras destroyed apartment. The 20 nurses that were working there and all the patients in the clinic were missing and their bodies were presumed to be buried under the rubble. That site was not cleaned up for a couple of years.


There were tent cities all over México City for about ten years or more. Every park, and park strip was full of tents for people that had lost their homes in the quake. There were still people living in tents there in 1997. The city government was having a hard time getting residents to vacate them.


Besides the obvious cheating on building specifications and standards, the typical masonry construction used in México is particularly vulnerable to earthquake damage. A rigid building, no matter how strong, will be the first to collapse during an earthquake. A flexible building, such as a wood framed house, or a building specifically engineered to flex during an earthquake is the most likely to survive.


All buildings will collapse if the quake is severe enough though. A good rule to follow is if a severe quake lasts uninterruptedly for one minute, get out of the building. If you are taking a shower on a freezing night, if you want to live, get the hell out.


Yesterdays quake was kind of a non-event at this distance from the epicenter.


Rex
"The supreme happiness of life is the conviction that we are loved" - Victor Hugo


tonyburton


Apr 28, 2009, 10:44 AM

Post #6 of 9 (2179 views)

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Re: [Papirex] Ahora, encima de todo

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A minor correction to Papirex's description of Richter scale variations. Each whole number increase (ie from 5.0 to 6.0) represents a ten-fold increase in amplitude (or about a 30-fold increase in energy). Because the Richter scale is logarithmic, the way in which this difference (between whole numbers) is divided between each decimal place is not uniform. Hence, for example, the difference between 5.1 and 5.2 is not the same as the difference between 5.4 and 5.5.
Searching using a famous search engine will get you more than you ever wanted to know about this topic!


Papirex


Apr 28, 2009, 12:15 PM

Post #7 of 9 (2160 views)

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Re: [tonyburton] Ahora, encima de todo

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You are right Tony. I am aware that the severity indicated by the numbers and fractions on the Richter scale are not lineal, but it has been many years since I saw the definitions of that scale, and I did not feel like doing the research again for my last post. The doubling of the severity for each decimal is simply a rule of thumb, it is accurate enough for a layman I think.


Rex
"The supreme happiness of life is the conviction that we are loved" - Victor Hugo


tonyburton


Apr 28, 2009, 12:56 PM

Post #8 of 9 (2149 views)

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Re: [Papirex] Ahora, encima de todo

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Rex, For what it's worth, a doubling for each decimal point would amount to 1024 times the energy for each whole number increase on the scale, as compared to the (approximately) 30 times increase in actuality. It's a bit like grains of rice on a chessboard... Students are always amazed if you suggest that you'd be happy to work for only $0.01 for the first hour of a course, and then $0.02 for the next hour and $0.04 for the next and so on. It doesn't sound like much, but even for a 30-hour course, it amounts to a very handsome return! Tony.


Papirex


Apr 28, 2009, 2:00 PM

Post #9 of 9 (2135 views)

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Re: [tonyburton] Ahora, encima de todo

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You're right again Tony. It reminds me of the old doggerel we used to say when I was a kid, “The way to become a millionaire is to start with one Dollar and double your money every day for a month.” The next time I post something like this, I will not be so specific with my generalizations.


Rex
"The supreme happiness of life is the conviction that we are loved" - Victor Hugo
 
 
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