Plot earthquakes between specific concentric circles using equidistant projection

Hi, I am new to GMT. I have plotted earthquakes data using azimuthal equidistant projection. My code and plotted map are;

Code.dat (562 Bytes)
Earthquakes data:
earthquakes.dat (412.2 KB)
Plotted map:

My query is;

  1. How to plot earthquakes data only between concentric circles of 70, 140 degrees as shown in blue colour on plotted map considering (centerN, centerE) values?

Kindly help me. Thanks.

Several possible ways I think:

  1. Use mapproject -G<lon/lat>+ud to compute distance in degrees from your center, then use gmtselect -Z to only pass those in your 70-140 range to plot.
  2. Lay down a clip path so that you only see the ones you want in that donut. This means making a polygon in geographical coordinates or work with Cartesian circles given you map size.

I would do option 1 I think.

Thanks for help. I have plotted map using option 1, which you mentioned. The commands which I used are below, have a look on these commands to see these are correct.

  1. calculate distance in degrees from center
    gmt mapproject earthquakes(lon,lat) -G$centerE/$centerN+ud > earthquakes_distance_degrees
  2. plot earthquakes only between 70-140 degrees
    gmt select earthquakes_distance_degrees -Z70/140 | gmt psxy -Rg -JE -Sc0.16c -Gbrown > Map

Apart from this, I want to label my map as in attached image.

My query is how to draw lines from center to outer frame circle (black lines) and label these lines at outer frame with values (0,60,120…) degrees. What way/commands can be use to do this task. Kindly help.

Well, would it not just be an layer of basemap using basic polar (cylindrical) projection -JP?

Hi, I have plotted the map with labels of outer circle using (JP) projection. Following way used to get it;
gmt psbasemap -Rg -JP5i+a -B30g30 --FORMAT_GEO_MAP=+ddd

" Now adding above layer to the first map of this post:
gmt begin Map png
gmt psbasemap -Rg -JP5i+a -B30g30 --FORMAT_GEO_MAP=+ddd
gmt pscoast -Rg -JE141/39/170/5i -A100000 -Gdarkgrey -Swhite
gmt psxy -Rg -JE -SE- -W0.6p,blue << EOF
$centerE $centerN 15540
$centerE $centerN 31080
gmt end show

Output map:

I think the way which I used above for adding outer frame with label is correct?

Now how to draw lines from map center (centerE=141, centerN=39) to the outer circle frame annotation points (0-330). Thanks.

Please, wrap your code in triple backticks ```