Charts should not be used as map lessons

Like Australia-based reader Ken B., I don't understand why many chart designers insist on using charts to deliver lessons to the public on map geography. Here is a recent example from Down Under, on earthquakes: (click on this link for the interactive version)

Was there a quake that shook the middle of the Pacific? Did a new geological formation give New Zealand a Pinocchio nose? No and no. The ugly presentation of the 2010 and 2011 Christchurch earthquakes -- as two ends of a dumbbell -- makes clear the straitjacket that maps are when it comes to delivering quantitative information.

Besides, the bubbles represent the relative magnitude of the quakes when one would hope that their sizes represent the geographical extent of the damage; at least, that would be information that has a spatial dimension.

The location of the quake is the only data with a spatial dimension surfaced on this plot. The only purpose of the map background is to tell us where Christchurch, Sichuan, etc. are on a map. In order to deliver this map lesson, the designer has to hide all of the more interesting data, like the relative magnitudes, the time-lines, the extent of the damage, the mortality rates, etc. In my mind, that is a very poor tradeoff.

Comments

[Basil]

Agreed this was not a very informative map. I liked the intercative nature from the link. I appreciate the blog because I now know that Christchurch is in New Zealand. I believe the little dumb bell thing is weird. It messes up the whole spatial dynamic which wasn't that great to begin with.

[Chris Pudney]

A somewhat better treatment by Peter Aldous. You can switch between spatial and histogram views, and compare casualties and magnitude.