On the Hypothesized 188 Day Quake Cycle

For the last year or two, conspiracy theorists have made a big ruckus every 188 days because they think that a big earthquake will hit. Some say that it is a sign of God at every 188 days there is a huge earthquake; others think that it has a link to solar flares or Coronal Mass Ejections. However, with some simple math and fact-checking, this "pattern" can be disproven.

So, let's start with the numbers:

Starting with the 188-day date of 2012/03/20, and going back 5 years takes us to 2007/03/20. Between these two dates, there are (365)*(5)=(1825) approximate number of possible days. The total number of 7<x<7.9 quakes that happened in those 1825 days are 86; the number of >8 quakes in the same time period was 7. Thus, the total number of significant quakes between 2007/03/20 and 2012/03/20 were (86)+(7)=(93).

Now, we can find the probability of a >7 magnitude quake occurring on any given day over the 5 years by dividing 1825 into 93. The answer is approximately 0.05, or 5%. So, let's look and the quakes closest to the 188-day periods:
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 can calculate the probability of quake greater than magnitude 7 occurring exactly 188 (even 189 if you wanted to) days apart in a 5 year period of 1825 days by figuring (10)/(1825), or 0.05 or 5%. This leaves a 0.995 or 99.5% chanctat 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)=(0.6)=(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, and 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 odds.

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.

This means that there are two possibilities:

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, not 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.

You can choose for yourself, but facts and numbers speak for themselves. Please check your facts; even if I'm wrong on the math, I think I have established that there is no pattern here.

Probability:
http://www.easycalculation.com/statistics/learn-multiple-event-probability.php
http://www.easycalculation.com/statistics/probability.php

Quake Stats:
http://earthquake.usgs.gov/earthquakes/eqinthenews/2012/
http://www.easycalculation.com/statistics/learn-multiple-event-probability.php

Date Math:
http://www.timeanddate.com/date/dateadd.html