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Name: brandon s pincus
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1999


Question:
How many earthquakes are there usually in a year?


Replies:
Nobody knows exactly how many earthquakes there are per year since many of the really small earthquakes go unrecorded. Generally, an earthquake must be at least magnitude 5 to assure that it is recorded by a seismograph somewhere on earth. Over the last ten years or so, there have been an average of 1656 magnitude 5 or larger earthquakes each year. (This information is from the National Earthquake Information Center of the U.S. Geological Survey in Golden, Colorado.)

As a rule of thumb, for every magnitude you drop down, there are roughly ten times more earthquakes. So, if there are 1656 magnitude 5 or larger earthquakes per year, there are about 16,560 magnitude 4 or larger earthquakes per year. Nobody is sure how far down this rule of thumb applies, but just for fun, let's take it down to magnitude 1. We would expect 10,000 times more magnitude 1 earthquakes than magnitude five earthquakes following our rule of thumb; this would give 16,560,000 earthquakes larger than magnitude 1 each year. Yikes!

-Grant



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