Goal: In this lesson you will examine the locations of earthquakes that have caused tsunami effects in Africa and the effects these tsunamis have had on the country.
GIS Skills Involved:Map symbolization and measuring distances on a map.
Materials: To complete this lesson you will need ArcGIS software and the Africa Lesson data (Download the Data for Activities 4-7).
Step 1.Let’s make a map in ArcGIS showing tsunami’s in Africa. Open ArcGIS and start with a new empty map.
Step 2.Use the Add Data tool to add the following shapefiles: country.shp, cities.shp, t_source.shp, and t_effect.shp.
Step 3.Now let’s rename the layers. Right-click on the layer name, select "Properties" and click on the "General" tab. You can enter the new name in the box next to "Layer Name".
Step 4.Display the Cities layer as a Graduated Symbol. Double click on the Cities layer to access the Layers Properties and click on the Symbology tab. Click on "Quantities" and select "Graduated Symbol". Select "Population" for the Value Field, click Apply and close the Layer Properties dialog box.
Step 5. Display the Tsunami Effects as bright blue stars. Double-click on the Tsunami layer to bring up the Layer Properties, and click on the dot symbol. Pick the green star symbol, change the size to 14 and make it a bright blue color.
Step 6. Next, make the Countries layer transparent and the Tsunami Sources symbols red. Open the Layer Properties or click on the symbol to open the "Symbol Selector" for Countries and choose "Hollow". For the Tsunami Sources layer, change the size to 8 and the color to red.
Step 7. Arrange the layers in your view window in the following order - Tsunami Sources, Tsunami Effects, Cities, and Countries.
A) Use the Identify tool and find the two cities with a population greater than 2 million that you believe to be most at risk from a tsunami in Africa.
B) Why do you believe these two cities are the most at risk?
C) Open both the Tsunami Effects attribute table and the Tsunami Sources attribute table (right click on each —> Open Attribute Table). Arrange the two tables next to each other so that you can compare the dates. By comparing the date columns, determine which Tsunami Sources caused Tsunami Effects in more than one location. Leave the tables open for the next question.
D) When an earthquake causes a disturbance in a lake rather than in the ocean it is called a "seiche". Determine the date and name of the city and country where the Tsunami Effect was a seiche rather than a tsunami.
Step 8.Now let’s use the Measure tool to determine the distance between the 2 tsunamis on the northwest coast of Africa. First we must make sure our map is set to the correct projection. Go to View —> Data Frame Properties and click on the Coordinate System tab. Click "Predefined" and then "Geographic Coordinate Systems". Select "World" and choose "WGS 1984" and click "OK". Next, click on the on the Measure tool on the tool bar. Click once on a starting point and double click on the ending point. A pop up box will appear with the value (see image on right). The distance should be approximately 515 km or 319 miles. You can change the units by using one of the tools on the pop up box.
E) Zoom back out to the full extent of the map using the Full Extent tool . Examine the tsunami source in the Atlantic Ocean northwest of the coast of Morocco. What year did it occur? How far did the tsunami travel from its source to where it hit the shore? Hint – use the Identify and Measure tools.
Step 9.Print a copy of your map layout (View —> Layout View).
Save your project and exit ArcGIS.
*** End of Africa Activity 6 for ArcGIS ***
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