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Exploring Africa's Physical and Cultural Geography Using ArcView

Activity 5: Earthquakes, Volcanoes, and Faults in Africa

Instructions for Students

Goal: In this lesson you will examine the locations of earthquakes and volcanoes in relationship to faults, and the impact on the countries in Africa to gain a better understanding of the human dimension of natural hazards in Africa.

GIS Skills Involved: Map symbolization and creating map layouts

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

Step 1. Let's make a map in ArcView showing the locations of large earthquakes, recently active and historic volcanoes, earthquake faults, and population densities in Africa. 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): country.shp, popden.shp, faults.shp, afr_eq.shp, volrecen.shp and volafr.shp. Put a check mark next to each one to make them visible.

• The popden.shp file contains population density information for Africa.
• The faults.shp file contains faults in Africa.
• The afr_eq.shp contains earthquakes greater than or equal to magnitude 6.5 on the continent of Africa.
• The volrecen.shp file lists the last eruption of volcanoes that have been active within the last 50 years on the continent of Africa.
• The volafr.shp file contains all known volcanoes in historic and modern time periods on the continent of Africa.

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

Step 3. Now let’s rename the themes. 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:

• Rename the afr_eq.shp layer to Earthquakes
• Rename the volrecen.shp layer to Recent Volcanoes
• Rename the volsafr.shp layer to Historic Volcanoes
• Rename the faults.shp layer to Africa Faults
• Rename the popden.shp layer to Population Density

Step 4. Arrange the themes so they are in the following order – Recent Volcanoes, Historic Volcanoes, Earthquakes, Africa Faults, County, and Population Density.

Step 5. There are two types of faults in our Africa Fault theme: normal faults (referred to here as rift faults) and thrust faults. Let’s display them both as Unique Values. Double-click on the Africa Faults theme to bring up the Legend Editor. In the Legend Editor window select "Unique Value" as the Legend Type and "Type" for the Values Field. Double-click on the line symbol next to the value "rift" to bring up the Pen Palette. In the Pen Palette window change the size to 2. Click on the paintbrush icon to bring up the Color Palette and choose a bright green. Next, double-click on the line symbol next to the value "thrust-fault" and change the size to 2. Click on the paintbrush icon to bring up the Color Palette and choose a light blue. Click Apply in the Legend Editor to apply your changes to the view.

Step 6. Now let's display the Population Density Theme as a Graduated Color. Double-click on the Population Density theme to bring up the Legend Editor. In the Legend Editor window select "Graduated Color" as the Legend Type and "Density" for the Classification Field. Select "Yellow Monochromatic" for the Color Range (see image below). Click "Apply" in the Legend Editor to apply your changes to the view.

A) What areas in Africa have high population densities (6-9), and also have some risk from earthquakes and volcanoes?

Step 7.Change the colors, sizes, and symbols of the remaining themes:

• Make the Country theme transparent.
• Make the Earthquakes symbol a blue color and size 10.
• Make the Historic Volcanoes symbol red triangles, size 10.
• Make the Recent Volcanoes symbol purple triangles, size 14.

B) Where (country) and when (year) did the last volcano erupt? Hint: Sort one of the fields in the Volcanoes Theme Table in descending order (it might also help to turn the other themes off so you see just the volcanoes).

C) Which country in Africa has the most historic volcanoes (to see country names make sure the Country theme is selected and use the Identify tool to find the country name)?

D) Which country in Africa has the most recent volcanoes and is most at risk from volcanoes that may erupt in the future?

Step 8.Create and print a few different map layouts. Select a few different theme combinations and print the layouts. For example, you can make a map showing recent and historic volcanoes and countries (turn the country labels on by going to Theme —> Auto-Label), or a map showing Earthquakes and Faults.

Save your project and exit ArcView.

*** End of Africa Activity 5 for ArcView ***

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