5.6 Shaking – What does that mean?

According to the US Geological Survey, the earthquake that shook my house had a 5.6 magnitude, making it the strongest earthquake in Oklahoma to ever be recorded.

Can anyone tell me what 5.6 means in comparison to California earthquakes?


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Mere Havoc
  • A 5.6 is a good sized quake.  For comparison, the Loma Prieta earthquake of 1989 (during the world series) was a 6.9, and the Northridge quake of 1994 was a 6.7.  Those were two strong ones that I remember.  Here’s a list of the CA quakes though (the famous SF quake of 1906 was a massive 7.8):


    • jim_m

      Remember also that the Richter scale is logarithmic so every 1 point increase in intensity is a factor of ten times more powerful.

      • You know it.  So there’s a big difference between a 5.6 and a 6.9, that’s for sure.  But still, a 5.6 is pretty solid.  Definitely enough to cause damage.

  • Anonymous

    I’ve lived in Caifornia virtually my entire life…a 5.6 earthquake out here is one that makes people say: “Hey, I think that was an erthquake”.  Not too much more.   

    When it gets above 6.0 then we take it more seriously…seriously.

    BUT, the Midwest (and most of the country except here) has lots and lots of unreinforced masonary structures…and that is NOT GOOD in any size earthquale.  The mortar liquifies and bad things happen.

    Be safe, ya’ll.

    • Anonymous

      Yeah.  5.6 will wake you up.  And which point you’ll roll over and go back to bed.  What most folks don’t realize is that the Richter Scale is logarithmic.  Each increase of a whole number (example from 4 to 5) means the quake is TEN TIMES bigger than the previous number.  By the time you get to a “6”, you’ve got some serious shaking going on.

  • Anonymous

    5.6 is Mother Nature’s way of saying “Mr. Norris, your martini is ready.”


  • Tanuki Man

    It wasn’t an “earthquake.” It was a Sooner Boomer.

  • OP

    5.6 gets your attention in CA, and pretty much anywhere here on the west coast. With no structures or roadways built to earthquake codes in OK, a 5.6 could cause a fair amount of damage depending on the duration—and it looks like it did. (Duration of the quake is what gets to me. I was in San Jose during the ’89 6.9 quake and that lasted only 15 seconds. Then I was in the ’01 Nisqually quake here in Seattle and that was a 6.8 that last 45 seconds, and that was far, far worse because it felt like it wouldn’t end.)

    But in terms of strength, the ’89 quake was 89 times stronger than the 5.6 quake you felt. Here’s a calculator.


  • Anonymous

    It means Gorebal warming is true!

  • Anonymous

    The New Madrid line is waking up after a 200 year snooze..  You might want to check into earthquake insurance.

    Here’s what I check every day (but relocated to your environs):


    You might also want to keep an eye on this map:


    I check this one but I don’t think you have much to worry about there:


    • Anonymous

      If New Madrid goes, I don’t think insurance will help much. You might not be around to collect. Or the insurer might not be around to collect from…


  • Anonymous

    It means your friends from California will make jokes about you for the next six months.

  • Anonymous

    I think I can add a fair perspective here, as a Califonian living in DC.  While I have always felt myself to be fairly knowledgable on seismology, the idea that the East Coast earth crust is fundamentally different than the West, thus allowing seismic waves to travel much farther, was news to me.

    I can tell you that the August 23rd, 5.9 quake was as strong as any I have ever felt. (I STILL can’t get over it. DC!!! f’r criminy sakes!) I was floored to hear it was felt in Connecticut and in tall buildings in Madison, WI. So the type of rock/crust involved is apperantly a huge factor along with the actual Richter numbers. 

  • Anonymous

    Aside from the magnitude, the form of the waves (compressional, horizontal shear, vertical shear, some combination) can also have a significant effect on the type and severity of the damage.