An Update on 2011’s Large Magnitude Earthquake Activity

Yesterday a 5.8 magnitude earthquake in Virginia dominated news headlines in the U.S. For those living outside the U.S. who may wonder why a 5.8 magnitude earthquake would be the top news story in the U.S., most people living on the east coast of the U.S. are not accustomed to experiencing earthquakes like other areas of the world and like other areas of the U.S.

After watching U.S. television news coverage of the earthquake, including one television show where the host wondered whether we are seeing an increase in earthquake activity, I thought it would be a good idea to provide an update on where we stand this year versus other years in terms of large magnitude 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. Magnitude 8.0 and greater earthquakes are so rare that there is no need at this time to update that study (in fact, none have occurred since I published my studies). However, there have been several magnitude 7.0 and greater earthquakes since I published my study about trends in magnitude 7.0 and greater earthquake activity earlier this year.

• Today I’ll provide an update to my study about trends in 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).

• Note: the U.S. Geological Survey reports that a 7.0 magnitude earthquake occurred today in Peru. This earthquake has not yet been included in the PDE data set. I have included this new earthquake in the graph.

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

Thus far, we have had 15 magnitude 7.0 and greater earthquakes this year, including #15 in Peru today. In view of that, 2011 would approximately be an average year compared to what happened from 1900 to 2010 if the year ended today. However, the year does not end today as we still have more than four full months remaining this year.

• If magnitude 7.0 and greater earthquake activity continues at its 2011 pace, we would finish 2011 with approximately 23 magnitude 7.0 or greater earthquakes or one more than the number that we had in 2010. If that were to occur, 2011 would qualify as one of the Top 10 most active years since 1900.

Magnitude 7.0 and greater earthquakes have not occurred 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 has picked up since July 1. 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 – August 24	5
Total	15

In sum, we are still on track for a well above average year in terms of magnitude 7.0 and greater earthquake activity. In fact, we almost already have an average year’s worth of magnitude 7.0 and greater earthquake activity in the first eight full months of this year.

There’s no guarantee that we will see many more magnitude 7.0 and greater earthquakes for the rest of the year. However, there is also no guarantee that we won’t see many more magnitude 7.0 and greater earthquakes for the rest of the year. We’ll just have to see what happens for the rest of the year…

Regardless of what happens for the rest of the year in terms of earthquake activity, I personally expect the number of large magnitude earthquakes to increase in the coming years as we approach the End Times…