Data Viz Done Right

July 9, 2018

Makeover Monday: Have volcanoes nearest to a tectonic plate erupted more recently?

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Week 28 focused on volcanoes around the world and when they last erupted. Here's the original visualization:

What works well?

  • Including a description for how to interpret the chart
  • Ordering the volcanoes from front to back according to elevation above sea level
  • Coloring by the number of eruptions since 1893
  • Excellent tooltips

What could be improved?

  • Where is sea level? Some of the volcanoes are below sea level. You can't really size by negative feet below sea level.
  • There's no explanation for why some of the volcanoes have labels.
  • Make it more clear where the based of the volcano starts. I assume it's at the bottom of the viz.
  • Include reasoning for why 1893 is when the counting of the eruptions starts.

What I did

I started by creating an Alteryx workflow that took the volcanic eruptions data and plotted the volcanoes onto a 250 miles grid of the world.



I then created a custom Mapbox map on which I included the tectonic plates, which I got the boundaries for as a shapefile from sciencebase.gov, imported it into Alteryx, created points, got the lat/lon and exported as a CSV so that I could import it as a layer in Mapbox. Here's what I ended up with, which was fun to create, but not insightful at all.



I had to start all over, so this time I decided to look at how far each volcano was from the boundary of the nearest tectonic plate. Again, Alteryx to the rescue!


Once I had the data I needed, I created a few calculation to help me create a simple quadrant chart that clearly show that the nearer a volcano is to a boundary of a tectonic plate, the more recently it erupted. All of that totally makes sense given what we learned about geology in school.

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