Where 2011 Ranks Historically in Terms of Magnitude 7.0 & Greater Earthquake Activity

Earlier this year I published a study about trends in magnitude 7.0 and greater earthquake activity over the past 100 years and a study about trends in magnitude 8.0 and greater earthquake activity over the past 100 years.

• In August I provided an update to the study on the trends in magnitude 7.0 and greater earthquake activity after a 5.8 magnitude earthquake impacted the east coast of the U.S.

Now that it is the end of the year I thought it would be good to provide another update to the study about trends in magnitude 7.0 and greater earthquake activity. Today I’ll show you where 2011 ranks historically in terms of magnitude 7.0 and greater earthquake activity.

I again utilized two data sources to account for the magnitude 7.0 and greater earthquakes that have taken place since 1900.

• The U.S. Geological Survey’s Centennial Earthquake Catalog data set. I rely on this data set to account for magnitude 7.0 and greater earthquakes that have taken place from 1900-1972.

• The U.S. Geological Survey’s Preliminary Determination of Epicenters (PDE) data set. I rely on this data set to account for magnitude 7.0 and greater earthquakes that have taken place between 1973 and today.

The following (updated) graph illustrates magnitude 7.0 and greater earthquake activity each year from 1900 to today (link to the chart in case you are unable to see it on your screen).

Recall that I also used the U.S. Geological Survey’s data to calculate the following summary statistics about magnitude 7.0 and greater earthquake activity from 1900 to 2010:

• Average # Per Year: 15.78
• Median: 15
• Standard Deviation: 4.82

We had 20 magnitude 7.0 and greater earthquakes this year. In view of that, 2011 was an above average year compared to what happened from 1900 to 2010. In fact, 2011 ranks as one of the Top 17 most active years since 1900.

Magnitude 7.0 and greater earthquakes did not occur at regular intervals this year. The first three months of 2011 saw a lot of magnitude 7.0 and greater earthquake activity while next three months saw relatively little activity. Magnitude 7.0 and greater earthquake activity picked up in the third quarter of 2011, but quieted down in the final part of the year. The following table provides a comparison of magnitude 7.0 and greater earthquake activity at different periods in 2011.

Time Period	# of 7.0+ Magnitude Earthquakes
January 1- March 31	8
April 1- June 30	2
July 1 – September 30	7
October 1 – End of 2011	3
Total	20

I hope you found this article on where 2011 ranks historically in terms of magnitude 7.0 and greater earthquake activity informative. Despite the slight decline in activity this year from 2010 levels, I still expect the number of large magnitude earthquakes to increase in the coming years as we approach the End Times…