November 13, 2012 – Global Earthquakes by Month: I downloaded global earthquakes greater than or equal to 6.0 magnitude, from January 1, 1973 to November 13, 2012; and graphed the average by month (see above). For example, Jan. has 14.3 average earthquakes per month. Thus 443 earthquakes divided by 31 days in the month equal 14.3. This is done for each of the 12 months. February’s average number of days per month is 28.25.
This produces an interesting graph in that the high months of March (16.0), April (16.1) and October (16.0) are almost two standard deviations above the mean; while July is almost two standard deviations below the mean. This means that this is not a normal distribution and there is something else at work here. Additional, in depth research, is needed to ascertain what causes earthquakes to be distributed in this way. This is a complex question.
Over the coming months I will explore the causes of earthquake. I will discuss predicting an earthquakes magnitude, depth, location and time. The depth of an earthquake is very important in that a shallow low magnitude quake can cause significant damage, e.g., the Christchurch, New Zealand quake. This quake was 5+ magnitude but occurred directly under the city at a shallow depth, causing considerable damage.
Of course, the magnitude is all important as witnessed by two mega-quakes and tsunamis e.g., December 26, 2004 off the coast of Sumatra, Indonesia and March 11, 2011 off the coast of Honshu, Japan.
The Master of Disaster