SHAKER STATS
Florida, Iowa, North Dakota, and Wisconsin
September 15, 2007
Holly Deyo
2007 is shaping up to be a big-bang-year for earthquakes! Indonesia's 8.4 Indonesian event has been followed by numerous large aftershocks.
Below you will find USGS earthquake statistics for the last 16 years. At the far right are two columns in purple and green. These compare the actual number of 2007 quakes to what usually occurs in any year and the percentage fulfilled for each magnitude.
In September 2003, USGS made an 'adjustment' to quake averges. The number of Richter 7's, 8's and 9's was revised DOWNWARD based on data since 1900. Instead of 2 magnitude 8's, now only 1 is considered normal. As of today's, we've seen 4.
Averages for magnitudes 4, 5 and 6 were revised UP based on observations since 1990.
The light green column reflects these 'new norms' while the light purple column shows what used to be considered average. Either way, Richter 8's are definitely up for this year. So are all of the other magnitudes except Richter 7's, looking at the pre--2003 figures. It is likely Richter 7's are lower due to the higher number of mag. 8's occurring. This indicates more energy is being released.
To see the percentage of quakes occurring for either the new or ol figures, look at the dark purple and darker green columns.
As for Richter 4, 5 and 6 events, we have either already exceeded expected quake numbers (by the old norms) or are very close to meeting the averages based on the new norms.
To say the least, 2007 is busy and there are nearly four months to go.
GLOBAL EARTHQUAKES JANUARY 1, 1992 - SEPTEMBER 13, 2007 (click on "Visit Author's Website" to view this chart)
*NOTES: At the end of September 2003, the USGS adjusted earthquake global averages for magnitudes 4, 5, 6 and 7. Most have increased, one magnitude decreased in shaker averages. This indicates an overall increase in earthquake activity. To get a fair comparison, both the "old" and "new" averages are included in the chart above.
The exact number of deaths from the January 26, 2001 India earthquake will never be known. According to the Red Cross, "Death toll reports vary widely, with some ranging from more 20,000 to as many as 100,000."