I’ve been thinking it would be interesting to visualize all the earthquakes which have occurred in the recent past. I started, of course, by looking for some data. Fortunately, the US Geological Survey provides comprehensive data on recent earthquakes. Unfortunately, they did not have a lot of historical information—providing 30 days, at most. So, over the past few months, I’ve been collecting the data in 30 day increments. I now have about five months of data, going back to August 16.









Earthquake Frequency

When I began to review the data set, I was shocked by the sheer number of earthquakes. I was surprised to learn that hundreds of earthquakes occur every single day. In September alone, for example, the US Geological Survey recorded 8,948 earthquakes!! Most of them were very small, falling well below the magnitude which can be felt by people (around 3.0). Alternatively, there were very few large earthquakes (greater than 6.0). This, I discovered, is how earthquakes generally work. There are lots of them at smaller magnitudes and they happen almost constantly, but larger ones occur much more rarely. The following graphic from the US Geological Survey demonstrates this quite nicely, while also showing the energy release and destructive power at each level of the scale.









Scale

With the data in hand and a better understanding of earthquakes overall, I began to visualize the data in Tableau. I started by using circles and sizing them according to the magnitude, but I quickly ran into a problem. As an example, I’ll use the Kaikoura Earthquake which occurred in November in New Zealand. Sized using magnitude, the visualization looks like this.







