Tuesday, November 20, 2012

Living Here: Earthquakes


There was a strong earthquake centered off the coast of Guatemala on November 7, and it was felt all over southern Mexico.

Sismos, quakes, normally don't merit front-page headlines in Yucatán, which is not known for seismic activity, but this one was felt in Mérida. I didn't notice it, but the newspaper reported the next day that the quake had been felt in the upper levels of some multi-story buildings in the north part of the city.

Various friends of mine in Mexico and Oaxaca states, closer to the epicenter, commented about the quake on Facebook. I called one friend in Oaxaca who reported that while startling, the quake seemed to have caused no damage in her area.

Since that time several more strong quakes have been felt in Mexico. All of this recent activity brought back to me a cascade of earthquake memories. All through my years in Alaska, quakes and smaller earth tremors were a normal occurrence. I also felt quakes as a teen in Colombia and later on visits to California. But fortunately the only loss we ever experienced from quakes was a few dishes and decorative bottles of Mom's that fell in the kitchen during a Fairbanks quake in 1967.

When the 1985 quake hit Mexico City I was in Israel, picking bananas on a farm in the Western Galilee. Several of my co-workers were Mexicans. What I recall vividly is how frantically they followed the news, and how one of them tried, for days before achieving success, to get word of her family. Now, interestingly, I know several chilango families who moved from Mexico City to Mérida in the aftermath of that event.

In August 2002, as I was searching for a home in Mexico, I visited the city of Colima, just a bit inland from Manzanillo on the Pacific Coast. I was enchanted by the area and its mountains, Colima's proximity to the coast, and interesting old houses in the city center. I looked at several that were for sale. Then a few months later back home in Alaska, I tuned in radio news one morning to learn that a massive quake had shaken the area. When I had time to watch video and see photos of the damage, I saw that some of the very streets and buildings that I'd looked at were now rubble. As a result, Colima moved quite a few notches down my list of possible Mexican hometowns.

I really like old Mexican architecture, but one of its problems is that although the stone, brick or adobe buildings with their thick walls are stout, they can be extremely fragile in quakes because they are heavy and built without reinforcing steel of any kind. Yucatán is not known for earthquakes, and Mérida has more intact colonial buildings than any city in the country outside of Mexico City itself. That so many of these very old, un-reinforced buildings are still standing was to me a good sign that Yucatán is a fairly earthquake-safe zone. A year after visiting Colima and eight months after the Colima earthquake of 2003, I bought my house in Mérida.

However, earthquakes do originate on the Yucatán Peninsula, according to an interesting news item published in El Diario de Yucatán a few days after the recent tremors in Mérida. The article relates that the most notable in recent times was a quake of magnitude 4.2 on the Richter scale, centered in Quintana Roo in 2010. This shaker was strongly felt in Ticul, little more than an hour's drive from Mérida.

The article quotes an investigator in the Dept. of Seismology at the Universidad National Autonoma de Mexico (UNAM) in Mérida as saying that little is known about what seismic faults exist in the Peninsula, and for this reason temblors in the Yucatán are little understood. He urges additional research into the matter, stating, "We need to further investigate the active faults, to see if they are large or small, and to find out if a disastrous earthquake could occur in the Peninsula."

Mérida and the Yucatán's population is growing rapidly. We have lots of old buildings here, and new construction often is not built with earthquakes in mind. This suggestion sounds like a good idea.


8 comments:

  1. Sometimes, the earth needs to move before we do.

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    1. How very true.

      Interestingly, the final draft of this post was about twice as long when it included all of my old earthquake memories. I posted, then decided it was terribly long (a problem of mine...), so I went back in to cut most of the Alaska quake memories out in the interest of keeping readers from tuning out prior to the final paragraphs. But the cut material demonstrated your statement even better than the material I didn't edit.

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  2. It is interesting and surprising to hear more and more about unmapped earthquake faults in different countries. New Zealand's devastating one occurred on a previously unknown fault. On the West Coast maps, many faults appear to stop right at the U.S./Canada border (on the U.S. side). I've read that prior to the Haiti quake in 2010, that region's fault lines had not received as extensive study as other seismically active areas in the region.

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    1. Yes it is interesting to discover that we really do not know much about faults outside of a couple of very well-known and heavily-populated areas, California, for instance. There is a lot we don't know; in fact we've barely scratched the surface. That certainly keeps things interesting.

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  3. A few years ago Lin Dorton (Crazy Gone Native) mentioned a quake site on her blog which I've found very useful, checking it often: http://earthquake.usgs.gov/earthquakes/map/

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    1. Thanks Eric. It's interesting. At this time it is possible to see a large swarm of aftershocks in the area of the Nov. 7 quake off Guatemala.

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  4. Chaffee has it with the USGS site, a very good source. I follow a site called AGU Blogospere for my geology fix every day. Good science people every one.
    I think the risk in northern Yucatan is from waves more than anything. There are any number of subduction zones offshore that can do weird things with the surface water. I had a friend killed in Cabo by a 2.2, the slippage was only a few miles away but it was on the sea floor-two fifteen footers came in and swept him off the rocks he was fishing on. I'm off to Antigua Guatemala in a few weeks, I worry more about the smokers there...

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  5. I was having lunch with friends recently and one of them said that she had just heard on the news of a quake, 7.7 on the Richter scale, in Vancouver, B.C.. I panicked, as that is a huge earthquake and Vancouver, my hometown, is comprised of closely packed high-rises. As it turned out the epicenter of the quake was off the Queen Charlotte Islands and the resulting tsunami that hit Vancouver Island was only about 26 centimeters.

    Obviously this was a relief but we have been told, in Vancouver, for years that "the big one" is coming. I think it is on the same fault line that runs up from San Francisco. When it finally happens it is likely to be devastating. Very worrisome.

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