Earthquakes have been a hot topic in the news lately after the M 7.1 earthquake in Ridgecrest, CA a few days ago. That strong earthquake followed a M 6.4 earthquake in Searles Valley, CA on July 4th, less than 10 miles from each other. Since the M 7.1 earthquake, there have been 41 aftershocks of M 4.0 to M 5.5.
If you include earthquakes of magnitude 2.5 or greater, there have been about 1485 earthquakes along the fault in that area over the last 7 days.
That’s certainly a lot of earthquakes registered on the Richter scale but the severity of an earthquake is more than just counting to 10. For example let’s compare a M 1.0 earthquake to a M 8.0 earthquake. The 8.0 is not just 8 times stronger than the 1 but rather 100,000,000, that’s 100 million, times stronger. Wait, what?
The Richter scale is not linear but rather logarithmic. A M 2.0 is 10 times stronger than a M 1.0. A M 3.0 is 10 times stronger than a M 2.0 and 100 times stronger than an M 1.0. A nifty trick to find out the strength of earthquakes relative to each other is to subtract the two earthquakes and than raise 10 to that power.
For example, the M 7.1 earthquake in Ridgecrest, CA minus the M 6.4 earthquake in Searles Valley, CA is 0.7. Now take 10 to the 0.7 power or 100.7 and that equals 5.01187233627. Therefor the M 7.1 is 5 times stronger than the M 6.4. That’s why higher magnitude earthquakes are so much more destructive than lower magnitude earthquakes. Anything above a 7.0 is considered to be major.