Statistics can be analyzed in quite a number of ways, many of which are neither right nor wrong, but simply different ways of looking at the data.
Similarly, while using USGS earthquake data, we can choose to view statistics in a number of ways. One interesting method is to view year-to-date statistics rather than using a rolling time frame (e.g. the past 12 months, etc…).
The USGS publishes statistical earthquake data, which we will use going back to the year 1990.
Annual Average number of earthquakes since 1990
Magnitude 8+ (1)
Magnitude 7 – 7.9 (14)
Magnitude 6 – 6.9 (134)
Magnitude 5 – 5.9 (1,319)
First, we let 30 days go by so as to avoid an unreasonable view of early fluctuations. Naturally, the further into the year, the more reasonable the viewpoint.
For example, since the average number of magnitude 7 – 7.9 earthquakes are 14.3 per year, how reasonable is it to say that we have a trend if we have already had 4 in this magnitude range, up through day number 39 of the year? This results in a YTD statistic, 262 percent of average! This is actually the present situation today.
14.3 per year = 0.03914 per day (14.3/365)
Today’s date, 8-Feb-2011, is the 39’th day of the year
39 times 0.03914 equals 1.526 (average number of mag.7 quakes up through day 39)
4 divided by 1.526 equals 2.62 (2.62 times the average, or 262% of avg.)
Although the magnitude 7 earthquakes are today 262 percent of the average, and while it does raise an eyebrow, the average will drop to 148 percent if we do not get another magnitude 7 quake for another 30 days, etc…
You see, as we proceed further into the year, we could begin to draw more reasonable conclusions as to being above or below average, although it is an interesting way to look at the data, even early on.
Up to date statistics using this method will be kept on this site (left sidebar) throughout the year. Let’s see how much shaking will be going on…
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