Mapping Earthquakes in Northern California

Table of Contents

  1. Mapping Earthquakes in Northern California
  2. Setting Up Your Workspace
  3. Downloading Data from Natural Earth
  4. Download Data from the Northern California Earthquake Data Center (NCEDC)
  5. Skill Drill: Download Data from the United States Census Bureau
  6. Adding California as a Basemap Layer
  7. Skill Drill: Adding the Humboldt County Boundary as a Basemap Layer
  8. Adding XY Data
  9. Changing the Map Projection of the Data Frame
  10. Representing Earthquake Magnitude Using Graduated Symbols
  11. Changing the Map Size and Position
  12. Creating an Inset Map
  13. Inserting A Map Title
  14. Inserting a Map Legend
  15. Inserting a North Arrow, Scale Bar, and Acknowledgments
  16. Exporting your map as a PDF file

Inserting a North Arrow, Scale Bar, and Acknowledgments

Cartographers use north arrows as a directional indicator. Not all maps need a north arrow, but including one is often expected. It is most important to include a north arrow when the top of the map is not due north.

From the main menu select Insert, then select North Arrow. As you can see, there are many styles from which to choose. It is often tempting for the novice mapmaker to choose elaborate and decorative styles. Picking gaudy north arrows is considered bad practice since it draws attention away from the map content. Always consider the map’s purpose and audience when choosing a north arrow style. Scroll through the north arrow styles and pick a north arrow appropriate for an earthquake map. When you are ready, click OK.

An image of the North arrow selector window
Click to view a larger sized image.

Find an inconspicuous spot to place you north arrow. Resize the north arrow symbol as needed.

You will need to include two scale bars, one for the main map, and one for the inset map. From the main menu select Insert, then choose Scale Bar. On the Scale Bar Selector, choose a scale bar style. Then, click the button that says Properties.

An image of the scale bar selector window
Click to view a larger sized image.

There are many properties you can change on the scale bar including color, font, and units of measurement. In this instance, you will change the Division Units to Kilometers. You may leave the other settings default and click OK. Then, click OK again.

An image of the scale bar properties window
Click to view a larger sized image.

The scale bar appears in the middle of the map outlined by a blue bounding box. Move the scale bar to the lower right corner, under the legend. Use the handles on the bounding box to resize the scale bar. As you change the size, notice that the numbers change. Scale units should be in round numbers that the map user can efficiently use and understand.  Resize the scale bar so that the number ends in an even 400 Kilometers.

An image of the scale bar resized to 400 kilometers.
Use the bounding box to re-size the scale bar and set the length to an even number.

In the Table of Contents, right click on the Humboldt County Inset and select Activate. The inset map should now have a dotted outline. Repeat the steps to insert a scale bar. Use the same style as the main map and change the units to kilometers. Resize the scale bar so that it says 200 kilometers and place it near the bottom of the inset map.

Caution! Be sure the inset data frame is activated or your scale bar will be incorrect.

In the next step, you will add your name to the map. It is also a good idea to acknowledge your data sources. Using the text tool and 10-point font, add your name and the date near an open space at the bottom of the map. Also include the following acknowledgment, “Earthquake data for this map were accessed through the Northern California Earthquake Data Center (NCEDC). State boundaries and country boundaries were obtained from Natural Earth. County boundaries were obtained from the United States Census Bureau.” Change the font to Ariel Narrow. When done, take a moment to save your map document before moving on to the next step.

An image of the acknowledgements for earthquake map
It is usually a good idea to acknowledge your data sources.