posted on Dec, 10 2012 @ 01:46 PM
I was just looking at some earthquake frequencies myself. I have a question that I'm sure has an answer but it seems odd to me.
If you look at the USGS website here,
you can see their frequencies for
earthquakes world-wide and in USA.
At the bottom of each chart is "no-magnitude" quakes. What exactly are no magnitude? Are they just quakes below .1?
The reason I ask is because of the astounding drop offs on the chart for no-mag quakes.
For the years 2000 - 2012 worldwide: no-magnitude quakes
2012: 3 ???
What happened? If you click back through the charts for the 90's the numbers range from 1826 to 5054 no-mag quakes per year. No big drop offs.
The same is true if you look at the USA's chart for 2000-2012 as well. It begins around the 400's and then ends at 8 in 2011 and 3 in 2012.
It seems the 1.0-1.9 mags go from the thousands to double digits from 2000-2012 for worldwide.
I'm sure there is a reason for this, I'm guessing some sort of technological advancements or something. Just curious what this is all about.
Nevermind, I'm a dummy. The USGS stopped monitoring earthquakes below 4.5 mag worldwide starting in 2009. Hence the large drop off. They only note
ones that were felt and had some kind of damage. I guess that doesn't explain the slope in the USA quakes, though.
edit on 10-12-2012 by
tport17 because: (no reason given)