Wednesday, August 26, 2015

Earthquakes - Part I

     I have spent my entire life in Southern California.  And so I am reasonably accustomed to earthquakes.  Although I must admit that I have never been in a building with significant damage caused by an earthquake. 
    The highest magnitude earthquake that I have felt was the 1952 7.3 Magnitude Tehachapi (Kern County). In Taft, where I lived, the Modified Mercalli Intensity was VII on the intensity scale, although it was much greater in Tehachapi.
Main Street, Tehachapi, after the earthquake of July 21, 1952. The two-story concrete (with wood floors and roof) structure in the background is the Catholic Youth Center. Despite the fact that most of Tehachapi's business section was at least partially destroyed, this building suffered little damage1. (Photo: World Wide Photo)
     One of the largest quakes after Europeans arrived in North America were the 1811-1812 earthquakes in New Madrid, Missouri.  From information on the USGS website2, people as far away as New York and Washington D.C. were awakened by the quake.  The extent of the area that experienced damaging earth motion, which produced Modified Mercalli Intensity greater than or equal to VII, is estimated to be almost 250,000 square miles.  Estimates are that moderate shaking (Intensity V or greater) occurred across one million square miles. Chimneys were toppled and log cabins were thrown down as far distant as Cincinnati and in many places in Kentucky. So it would be safe to assume that my ancestors who lived in Nelson County, Kentucky would have certainly felt the quake and possibly would have seen buildings that suffered damage.  I wonder what they would have thought about the quake.  Was there damage to their property?
My ancestors, who lived in Central Kentucky,
would have experienced an Intensity level of VII during the New Madrid Quake.

At the time of the Tehachapi Quake,
I lived in the region which is labeled with an Intensity VII

1. "Earthquake damage in Tehachapi - California Digital Library." 2008. 15 Aug. 2015 <>
2. "New Madrid Earthquakes 1811-1812 - Earthquake Hazards ..." 2009. 15 Aug. 2015 <>
3.The New Madrid Seismic Zone. 26 Aug 2015
4. California Earthquake Map Collection, 26 Aug 2015

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