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Exploring Africa's Physical and Cultural Geography Using ArcView

Activity 4: Plate Boundaries, Earthquakes, and Volcanoes

Instructions for Students

Goal: In this lesson you will create a map and examine the location and patterns of plate boundaries, earthquakes, and volcanoes in Africa and the world.

GIS Skills Involved: Map symbolization and spatial queries

Materials: To complete this lesson you will need ArcView software and the Africa Lesson data (Download the Data for Activities 4-7).

Map of global plate boundaries

Step 1.Let’s create a map of the world showing the locations of plate boundaries, earthquakes, and volcanoes. Open ArcView and click "OK" in the pop up window (this will create a new project with a new view). The next screen will ask if you would like to add data to the view. Click "Yes" and add the following shapefiles (navigate to the folder where you saved the Africa Lesson data and hold down the shift key to add more than one shapefile at a time): Continent.shp, Plates.shp, Earthquakes.shp, and Volcanoes.shp. Put a check mark next to each one to make them visible.

Step 2. Choose "Properties" from the View pulldown menu and rename the view to "Plate Boundaries, Earthquakes and Volcanoes". Click OK.

Step 3. Rename the themes to Earthquakes, Volcanoes, Continent and Plate Boundaries. To do this, make the theme active by clicking on its name (i.e., its name appears raised). From the Theme pulldown menu choose "Properties" and change the name. Do this for all themes.

Step 4. Make the Continent fill pattern transparent. Double-click on the Continent theme, double-click on the colored box, and click on the blank box in the upper left-hand corner in the Fill Palette (see image below). Click the "x" box in the upper left to close the Fill Palette. Click "Apply" in the lower right of the Legend Editor, and close the Legend Editor.

Image of Legend Editor window

Step 5. Now let’s change the size and color of the symbol for Earthquakes to blue circles. Double-click on Earthquakes, double click on the dot symbol, and click on the thumbtack icon to bring up the Marker Palette Marker icon. In the Marker Palette window change the size to 8. Click on the paintbrush icon to bring up the Color Palette Paintbrush iconand choose a bright blue color. Click Apply and close the Legend Editor.

Step 6. Now change the size and color for the Volcanoes and Plate Boundaries themes the same way you changed the Earthquakes. Make the Volcanoes theme red triangles and the Plate Boundaries theme a thick brown line.

Step 7. Arrange the themes in the View window so they are in the following order: Plate Boundaries, Volcanoes, Earthquake, Continent. To do this, simply click on the theme and drag it up or down while holding the mouse down.

Step 8. Answer the following questions using this map setup.

A) Where are the majority of the earthquakes in the world located in relationship to the plate boundaries? Why?

 

B) Where are most of the earthquakes in Africa located in relationship to the plate boundaries? Why?

 

C) A rift zone is where a continent is believed to be spreading apart, but not on a plate boundary. A rift zone causes magma to rise to the surface and erupt in a line of volcanoes. Zoom in on the continent of Africa. Based on the above information, in what African countries is the rift zone located (to see the country name click on the Identify tool identify tool icon and then click on the country)?

 

Step 9. Zoom back out so you can see the entire world. Let’s open the theme table and sort by a particular field. Make the Earthquakes theme active by clicking on its name. Open the Earthquakes theme table by clicking the Open Theme Table Button open theme icon. When the table opens, widen the window until the Magnitude column is displayed. Select this field by clicking on the field name "Magnitude". Click on the Sort Descending button sort descending icon to sort the records by Magnitudes from largest to smallest. Click on the first field, which should be the largest magnitude earthquake (9.3). The corresponding point should be highlighted in yellow on the map (you may need resize your windows and zoom in and out to find the point).

image of theme table window

D) When, and on which continent, did the largest magnitude earthquake occur (you may need to turn the continent labels on)?

Step 10. Now let’s figure out which volcano in Africa has the highest elevation by performing a spatial query. Click on the Query Builder tool and double click "Elevation" under the "Fields" category. Click the "greater than" symbol and enter a value of 2000 and click "New Set". All the volcanoes in the world with an elevation greater than 2000 should now be selected on your map. You will notice there are several volcanoes in Africa that meet this criteria. Go back and enter 3000, then 4000. Keep entering new values until only one volcano in Africa remains selected.

E) What is the name and elevation of the tallest volcano in Africa and where is it located?

 

Save your map and exit ArcView.

*** End of Africa Activity 4 for ArcView ***

 

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