Mapping failure,advanced edition

GG has complained a few times about poor maps in the professional literature, but a new entry has carried this to a new level. A new and intriguing paper by Alessandro Verdecchia and Sara Carena contains this figure:


This has the now-familiar “computer stupid” projection that GG complained about (and others have defended): 1 degree of longitude is shown as having the same length as one degree of latitude, a relationship only true at the equator. The scale shown is correct for north-south distances, but overestimates east-west distances by about 20% or so.  Strike 1.

What carries this to the next level is that important information here is the orientation of the faults. A Mercator projection will preserve angles (that is what it was always good for), but this projection will not.  A fault trending N45E, for instance, will be drawn here as trending about 52 degrees away from a north-south line. Strike 2.

The stereonets shown for focal mechanisms are not so distorted, so you cannot compare the orientation of nodal planes with the trends of faults as accurately as you should be able to. Strike 3.

Grr. As GG has said before, there is no excuse in the age of GMT and ArcInfo for stuff like this.  We can hope that the authors’ codes do not mirror their abuse of mapping software.

This again is the sort of mistake (and there is no defending this one!) that biases GG to question the ability of authors producing such maps. This is not what you want to do as an author!

Hopefully we’ll get a chance to come back and explore the suggestion here that the data available allow us to refine earthquake forecasts in complexly deforming regions.

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