As we trundle on to destruction on 21st December 2012 (NOT!) I thought it would be a good time to look at the year so far (To October 31).
The charts below are for Magnitude 6 or greater earthquakes using data from the ANSS catalog. Each chart can viewed full-size by clicking on the image.
Earthquakes 2012 to 31st Oct for Magnitude
The next chart shows the same figures, but with depths above the earthquakes. What is particularly curious is that the polynomial trend line of the magnitudes pretty much matches the polynomial trendline of the depths. I find that somewhat odd and have no explanation for it.
Earthquakes 2012 to 31st Oct for Magnitude with depths
Finally the energy output. To be honest this chart is difficult to read as not only are the numbers very large but the two Magnitude 8+ earthquakes swamp everything else. I have tried to make it display some part of a bar for every earthquake by setting the bottom of the scale to a negative number.
Earthquakes 2012 to 31st Oct for Energy
Converting that energy back to a magnitude the total so far for 2012 is Magnitude 8.72 if it all happened as one single earthquake.
There is a distinctly quieter period in the ‘middle’ and of later it has got busier, but this is NOT unprecedented. The Northern hemisphere often produces more earthquakes in the autumn/winter/spring months than it does in the summer. Since the bulk of the world’s land mass is in the northern hemisphere this does skew the figures slightly.