Ok, so I thought I would take a crack at this.... mostly because I have followed quakes rather closely for a number of years (due to my fascination
with their link to solar flares/CMEs) and would have seen this 188 day pattern emerge sooner. Plus, everyone on the internet is freaking out without
doing some simple math and fact-checking, so I thought I would ease the minds of the few who care to listen.
It's been a while since I've done probability so there is a chance (no pun) that I could be wrong, but I don't think I am.
So, let's start with the numbers:
Starting with 2012 and going back 5 years to 2007, taking us to 3/20/2007 to the day:
365 * 5 = 1825
- approximate number of possible days (possible outcomes)
2007-2012 total 7-7.9 quakes = 86
2007-2012 total 8+ quakes = 7
Total significant quakes = 93
(number of possible events)
Probability of a quake greater than 7 magnitude occurring on any given day over the 5 year period: 93:1825 = 5%
Now we need to know the total possible outcomes over the 5 year period for the 188 day cycles:
3/20/2012 (7.6 Mexico)
3/20/2012 - 188 days = 9/14/2011 (7.3 Fiji - 9/15/2011)
9/14/2011 - 188 days = 3/10/2011 (7.9/9.0 Honshu Japan - 3/11/2011)
3/10/2011 - 188 days = 9/3/2010 (7.0 New Zealand - 9/3/2010)
9/3/2010 - 188 days = 2/27/2010 (8.8 Chile - 2/27/2010)
2/27/2010 - 188 days = 8/23/2009 (closest is 8.1 on 9/29) off by +36 days
8/23/2009 - 188 days = 2/16/2009 (closest is 7.2 in Indonesia on 2/11) off by -5 days
2/16/2009 - 188 days = 8/12/2008 (nothing in August) completely off
8/12/2008 - 188 days = 2/6/2008 (closest is 7.4 in Indonesia on 2/20) off by +14 days
2/6/2008 - 188 days = 8/2/2007 (7.2 Vanatua - 8/1/2007)
This gives us 10 distinct events that have the possibility of occurring.
Using the same variables for possible outcomes, we calculate the probability of a greater than magnitude 7 quake occurring EXACTLY 188 (even 189 if
you wanted to) days apart in a 5 year period of 1825 days.
This gives us a probability of 10:1825 = .5% possibility of occurrence
that an earthquake will occur every 188 days AND be magnitude 7 or
greater. (or .995 = 99.5% chance it will NOT
happen exactly 188 days apart)
This is incredibly low odds.
Out of a 5 year period and a possible 10 attempts to fall within the 188 day cycle with a +/- of 1 day, we get 6 solid hits of 10. This gives a
probability of 6:10 = .6 = 60% that a greater than magnitude 7 quake will occur out of our 10 possible events.
This clearly shows that it is a
coincidence over the last 5 years, regardless of the last 5 occurrences being 188 days apart, the rest are not. The pattern would need to continue to
repeat going back to 2007 to be even close to giving this a real probability of greater than 90% (which is what you want to establish a pattern of any
kind, is to get as close to 1 as possible.) and it breaks down in 2009.
Take the .5% possibility that a 188 day cycle can occur, then factor the 60% chance that a magnitude 7+ quake can occur in that window, the odds
that a magnitude 7 quake occurring exactly 188-189 days apart in a 5 year period with the sampling of data is .003 or .3% - which again, is very low
For the sake of this argument, you can basically say the possibility of both the cycle and the quake occurring together perfectly are less than 1%.
Taking the 188 day cycle, and looking for a repeatable pattern that occurs, you can see that it is not a consistent pattern and the odds of it
occurring are so low, that it is almost impossible for it to happen as expected in a statistical probability of occurrence.
What this means:
1) There is no pattern. This is the most likely explanation. Geologically speaking, a 5 year window is nothing but it is enough to set a baseline
sample, so the fact that the pattern breaks down only halfway through that time slice demonstrates that it is a significant coincidence
a statistical probability of any kind
2) There is a pattern emerging
. This will require CLOSELY monitoring the next 188 days to see if another major quake occurs and then the
numbers will change, but not by much, because if we go back beyond 5 years, the probability decreases even more as there are fewer hits and greater
possible outcomes. This decreases probability, not increases it, contrary to what most people would like to believe.
3) The mind sees what it chooses.
Choose for yourself, but facts and numbers speak for themselves.
I don't believe there is a pattern here as much as I would LOVE for there to be one.
Please check your facts people. Even if I'm wrong on the math, I think I have established that there is no pattern here.... yet.