Joe Kington | 3 Dec 04:35 2008

Re: Plotting Structural Data on a Stereonet

It seems that there were some problems in the first Examples.tar.gz file that I attached.  Here's a version that should work.


On Tue, Dec 2, 2008 at 9:20 PM, Joe Kington <joferkington <at>> wrote:
Hi everyone,

I've been plotting a lot of structural data on a stereonet lately, and while this is possible in GMT, it can't be done directly.

To make things a bit easier on myself, I put together a python program to output lat,long pairs corresponding to the line or point representing a strike/dip, plunge/bearing, pole to a plane, or rake measurement. It reads strikes in azimuth or quadrant form, and assumes RHR if no dip direction is given.  It can also "unfold" data (e.g. rotate each measurement so that a given strike/dip is horizontal), for simple cases (non-plunging folds). Coupled with various GMT tools, you can also plot contours of poles to planes, find a best-fit plane to data (using fitcircle), etc.

Forgive me if I'm reinventing the wheel, here, but I don't know of any other software to plot data on a stereonet in linux.  Rick Allmendinger's software only works on mac and windows and doesn't produce (i.m.h.o.) as nice an output as GMT does.  My script makes it much easier to analyze and plot structural data using GMT's various tools.  It requires python 2.3 or later, but should work on any platform. (OSX or any recent *nix distribution should already have what you need. Otherwise, just install the latest version of python.)

Installation should be as simple as moving the script to somewhere in your $PATH and chmod +x.  More detailed instructions (and instructions for windows) are in INSTALLATION.txt.  Also note that "stereonet" alone will try to read from stdin and print to stdout, rather than printing a help message.  Try "stereonet --help" to see the usage.

There are several examples in the attached examples.tar.gz file. 

Also, the "unfolding" function hasn't been rigorously tested.  It's probably best not to use it for anything important.  There undoubtedly various bugs, but I think (hope?) its rather robust.

Let me know if anyone finds it useful,

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Attachment (Examples.tar.gz): application/x-gzip, 5188 bytes