(7) A simple location map¶
Many scientific papers start out by showing a location map of the region
of interest. This map will typically also contain certain features and
labels. This example will present a location map for the equatorial
Atlantic ocean, where fracture zones and mid-ocean ridge segments have
been plotted. We also would like to plot earthquake locations and
available isochrons. We have obtained one file, quakes.xym
, which contains the
position and magnitude of available earthquakes in the region. We choose
to use magnitude/100 for the symbol-size in inches. The digital fracture
zone traces (fz.xy
) and isochrons (0 isochron as ridge.xy
, the rest as isochrons.xy
) were
digitized from available maps [1]. We create the final location map
with the following script:
#!/bin/bash
# GMT EXAMPLE 07
#
# Purpose: Make a basemap with earthquakes and isochrons etc
# GMT progs: pscoast, pstext, psxy
# Unix progs: echo, rm
#
ps=example_07.ps
gmt pscoast -R-50/0/-10/20 -JM9i -K -Slightblue -GP300/26:FtanBdarkbrown -Dl -Wthinnest \
-B10 --FORMAT_GEO_MAP=dddF > $ps
gmt psxy -R -J -O -K fz.xy -Wthinner,- >> $ps
gmt psxy quakes.xym -R -J -O -K -h1 -Sci -i0,1,2s0.01 -Gred -Wthinnest >> $ps
gmt psxy -R -J -O -K isochron.xy -Wthin,blue >> $ps
gmt psxy -R -J -O -K ridge.xy -Wthicker,orange >> $ps
gmt psxy -R -J -O -K -Gwhite -Wthick -A >> $ps << END
-14.5 15.2
-2 15.2
-2 17.8
-14.5 17.8
END
gmt psxy -R -J -O -K -Gwhite -Wthinner -A >> $ps << END
-14.35 15.35
-2.15 15.35
-2.15 17.65
-14.35 17.65
END
echo "-13.5 16.5" | gmt psxy -R -J -O -K -Sc0.08i -Gred -Wthinner >> $ps
echo "-12.5 16.5 ISC Earthquakes" | gmt pstext -R -J -F+f18p,Times-Italic+jLM -O -K >> $ps
gmt pstext -R -J -O -F+f30,Helvetica-Bold,white=thin >> $ps << END
-43 -5 SOUTH
-43 -8 AMERICA
-7 11 AFRICA
END
The same figure could equally well be made in color, which could be rasterized and made into a slide for a meeting presentation. The script is similar to the one outlined above, except we would choose a color for land and oceans, and select colored symbols and pens rather than black and white.
[1] | These data are available on CD-ROM from NGDC (www.ngdc.noaa.gov). |