Wednesday, January 6, 2016

Earthquake Database

Last week friends of mine felt a 4.8 magnitude earthquake on Vancouver Island. So it seems like a perfect time to post some resources on data about earthquakes. As it turns out, depending on the magnitude, there are a lot of earthquakes that happen world wide each year. And we can get that data, almost realtime, from any number of earthquake databases. I like the one that the US Geological Service provides. This lets you set a few options and search earthquakes based on those options. The default is then a map that shows the result of your search.

The Analysis

Once you chose which options to use, then you have to get the data. I suggest that you limit your searches originally to those over magnitude 6 if you are looking at an extended time period (in 2015 there were over 140. If you play around with the magnitude (say dropping the threshold to 4.5) then you could get a huge amount (which you may or may not want). For example, if you drop that threshold to 4.5 there are over 6800 earthquakes found from 2015.

Once you get the data, you can just click the Download button on the top left to choose a CSV file that can be imported into any spreadsheet or Fathom. The obvious analysis here is a single variable set of the Magnitude (they call it mag in the data set). So you could do any number of histograms, box plots, dot plots etc as well as measures of central tendency and standard deviation. It's a really good data set for having students go through all the basic calculations needed when doing a single variable analysis.

Depending on when you get your data you will get outliers.

Usually the data will come out skewed to the right as most of the quakes are typically at the low end (this is regardless of what you choose as your threshold.
You can also do a neat "heat map" plot in Fathom by plotting the Longitude and Latitude (and thus getting a map) and then dragging the Magnitude onto the middle of the graph so that it appears as a colour on the spectrum.

Sample Questions

  • Determine the measures of central tendency for the magnitude of the earthquakes
  • Determine the five number summary for the magnitude of the earthquakes
  • Which earthquake(s) were the most extreme? Where they outliers?
  • How are the measures of central tendency affected if you remove the outlier(s) when looking at the magnitude of the earthquakes?
  • Determine whether the data for the magnitude of the earthquakes is skewed to the right or left.

Other Earthquake Data

If students are trying to do something more with their earthquake data (like analyze then make sense of it) they might try getting more info at IRIS (Incorporated Research Institutions for Seismology). There they have some of the same data and more plus other info that might be relative. Thanks to @frankmcgowa for that one

Download the data

Let me know if you used this data set or if you have suggestions of what to do with it beyond this.

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