Three years ago I published an article in Plus magazine debunking claims buzzing around on the internet about a supposed recent increase in earthquakes. In that article I showed in detail how anyone can analyze publicly available data to put such claims to the test. In the current post, as I did the last two years, I present an update on these earthquake statistics.
In the earlier Plus article, I showed how earthquake data can be downloaded from the USGS website and analyzed for any trends. I chose to look at earthquakes of magnitude 5 and larger (M5+), as those are the ones that can potentially cause damage or even casualties. I showed two graphs, one with monthly earthquake counts from January 1996 to December 2016, and one with yearly counts for the same range of years. For details, also on the statistical analysis, see the original article.
This data showed that there was indeed a significant build-up in number of earthquakes from the early 2000s until 2011. However, after the major M9.0 earthquake off the coast of Japan in March of 2011, there was a clear drop in number of earthquakes, bringing it back to the level it was about 10 years earlier, and staying at that level until the end of 2016.
Last year I updated these statistics up to the end of 2018, and in this post I also include all of 2019. The following plot shows the monthly M5+ earthquake counts (worldwide) from January 1996 until (and including) December 2019. The big spike is due to the March 2011 M9.0 Japan earthquake which caused many aftershocks. The red line is a 12-month running average.
The next plot shows the yearly counts for 1996 until (and including) 2019. It clearly shows that after the major 2011 event, the level of earthquakes dropped significantly and has since remained at a fairly constant level.
In conclusion, there is still no evidence at all that there has been a continuous increase in the number of earthquakes recently. There has been a significant increase during the first decade of the 21st century. However, since then things seem have gone back to “normal” levels again, and have stayed that way.
Just after posting this article I found additional data (but also based on the USGS database), with yearly M5+ counts going back to 1970. This additional data only goes up until 2012, but adding the numbers up to 2019 from my own analysis, the plot looks like this:
This makes it even more clear that post-2011 everything has been “business as usual”. The years 2007-2011 seem to have been somewhat of an exception. It will be interesting to find out if there is a known cause for this. As before, keep an eye out for next year’s update…