There has been an increase in major seismic activity from 1973 to 2009 (the years for which there is online information at USGS.gov) The following graph shows the total amount of "shaking" caused by all earthquakes of 7.0 magnitude or greater from 1973 to 2009. I assigned each 7.0 quake a value of one(1), each 8.0 quake a value of ten(10), and other magnitudes an appropriate Linear value. The proper measure of the total amount of seismic activity each year should be the Total of the Linear value of each quake times the number of quakes of each magnitude. This is because the Richter Scale is Logarithmic.  So, if you had three 6.0 earthquakes, two 7.0, and one 8.0 in "Year One", and in "Year Two" had three 6.0, two 7.0, and one 8.0 quake and one quake of 8.1; your graph would indicate an increase of 1 earthquake greater than 6.0 -- but in reality you would have experienced more than DOUBLE the amount of seismic activity ("shaking").  I...(Read Full Post)