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How can I plot earthquake epicenters on a MapViewer map using the pin size to indicate magnitude and color to illustrate depth?

Pin maps plot symbols at exact x,y locations but can only control symbol size and color with a single data variable. Symbol maps on the other hand can control symbol size and symbol color with two separate data variables, but they plot at the centroid locations of a boundary file rather than at exact x,y locations. Using a combination of these two map types, you can get the exact result you’re looking for.

 

Earthquakes.png

2015 Earthquakes within 100 KM of the coast of South America. Symbols are sized by magnitude and colored by depth

 

To get a boundary file of your pin map locations:

  1. Click Map | Create Map | Pin.
  2. In the Open Data File dialog, choose your data file and click Open.
  3. On the Map page in the Property Manager, change the Method to Uniform symbol.
  4. On the Symbol page, change your symbol Size to 0.001.
  5. If there are any labels displaying, go to the Pin Labels page and uncheck the box next to Show label.
  6. Click File | Export.
  7. In the Export dialog, set the Save as type to GSB Golden Software Boundary (*.gsb), give your file a name, and click Save.
  8. In the first Export Options dialog, check the boxes next to Export basic object IDs, Export object attribute list, and Export all worksheet data if PIDs match, then click OK.
  9. In the second Export Options dialog, click OK to complete the export.

 

To plot your symbol map:

  1. Click File | New | Plot to open a new plot window.
  2. Click Map | Create Map | Symbol.
  3. In the Import dialog, choose your GSB file and click Open.
  4. In the Import Options dialog click OK.
  5. In the Open Data File dialog, choose your data file and click Open.

 

To edit the symbol map to show two variables of data:

  1. On the General page in the Property Manager, set the Variable column to your magnitude column.
  2. If desired, in the Data Limits section, check the box next to Use user-defined limits and then specify a custom Min limits and Max limits.
  3. Click on the Map tab in the Property Manager.
  4. Set Proportional properties to Size and color.
  5. In the Size section, set the Proportional method, Minimum size and Maximum size. The minimum will be the size of the data point with the Min limits value form the General page, the Maximum will be the size of the data point with the Max limits value from the General page, and the Proportional method will dictate how points between those values will be sized.
  6. In the Color section, set the Data column to your depth column.
  7. Set the Fill colors and/or Line colors colormaps by clicking the existing colormap and choosing from the list of presets, or clicking the Custom colormap button to define a custom colormap.

 

Updated October 16, 2016

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