A Whole Lotta Shakin’ Goin’ On

I woke up this morning a little after 3:00 am because my bed was shaking.  I realized that we were having an earthquake but that we were not shaking violently enough to be worried.  My dog got up and walked over to me to make sure that his owners were safe and returned to his bed.  My daughter woke up and realized that she was feeling her first earthquake (or at least the first one that she knew about while it was happening).  My wife slept through everything.  I made a mental note to check the internet in the morning to see where the epicenter was located, the magnitude, and whether there was any damage.

But the quake was not so gentle everywhere as it was at our home.  The epicenter was north of San Francisco, in Napa.  It was magnitude 6.0 (the Loma Prieta quake in 1989 was a 6.9 – almost double the strength of this morning’s quake).  I don’t think that any deaths were caused by the quake, but there were several injuries – some quite serious.  Several gas mains broke, some water mains broke (with the result that an entire mobile home park burned without water to put out the fire), and about 30,000 people lost their power.

Earthquakes are the natural disaster here in California – but we don’t get tornados, hurricanes, bitter cold, or high humidity.  All in all, I consider northern California to be paradise – even with the earthquakes.


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5 responses to “A Whole Lotta Shakin’ Goin’ On”

  1. John Burnette says :

    I’m about to start the Exponents and Logs chapter in my PreCalculus class so I have to jump in here. The Richter Scale is a logarithmic scale so for each “bump” up by one point on the Richter Scale means the amplitude of the seismometer “wiggle” is ten times greater.

    Here’s where I learned something though: There’s a rather involved formula to calculate the energy released by an earthquake given it’s Richter Scale number. According to Wolfram Alpha, the energy released by a 6.9 quake is is 1.4 * 10^15 joules where a 6.0 earthquake releases 6.3×10^13 joules

    So if you’re measuring “size” of an earthquake by amount of energy released, a 6.9 magnitude quake is just over 22 times as big as a magnitude 6.0

    The “big one” is still out there – a la 1906 in San Francisco. That earthquake predates the Richter scale but modern estimates for the quake range from 7.7 to as high as 8.25 — significantly more than 2000 times the energy of your recent quake.

  2. John Burnette says :

    In our part of the world, the worry is getting hit by a hurricane. There’s a similar difference between a category 1 and a category 5.


    Category 1: Bring in your lawn chairs — throw a party.

    Category 5: You’ll be rebuilding your house, along with everyone else.

  3. John Burnette says :

    All of a sudden, I’m hugely concerned about what I’d consider an systemic risk to the American financial system. I was reading an article about California and the likelihood of earthquakes (the eventuality actually) and learned that only about 10% of homeowners avail themselves of specific earthquake insurance — because it’s specifically excluded from almost all regular policies.

    Given the prices of your homes out there, I’m guessing absolutely everyone has a mortgage. So, when it does happen, as statistically it almost certainly will, then it will be the mortgage holding banks which will be left holding the bag for massive losses.

    Why is this allowed to happen? If a 1906 earthquake happened today, wouldn’t it immediately cause huge numbers of bank failures?

    • Graham Burnette says :

      That is a really good point, John. A really major earthquake hitting San Francisco, Los Angeles or San Diego could impact the overall economy much like the 2008 financial melt-down. I don’t think anyone is considering that risk.

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