Exploring Africa's Physical and Cultural Geography with GIS

Activity 6 - Answer Key

Question 1 Use the Information button   to name the two cities and the two countries with a population greater than 2 million that you believe to be most at risk from a tsunami in Africa.  

Algiers, Algeria

Casablanca, Morocco
Question 2 Why do you believe these two cities and two countries are most at risk?  Defend your answer.

They are along the open ocean and not solely on a sea (such as the Mediterranean).

They are in areas that have been affected in the past by tsunamis.
Question 3 What other cities over 2 million in population have a risk of tsunamis in Africa?

 Lagos, Nigeria

Alexandria, Egypt

 
Question 4 Make the Tsunami Sources theme the active theme and zoom to the extent of that theme. Examine the source in the Atlantic Ocean northwest of the coast of Morocco.  During what year did it occur?  How far was the earthquake from where the tsunami struck the shore?

The Year 1755


Between 490 km and 635 km
Question 5 If the same earthquake struck today, name all of the coastal cities in Algeria and Morocco that could be affected. 

Algiers and Oran, Algeria

Rabat and Casablanca, Morocco
Question 6 What is the combined population of the coastal cities in Algeria and Morocco that could be affected?  Show your work.

The sum of the above 4 cities is:   6,631,541 people


Question 7 Use the Open Theme Table Button  to open both the Tsunami Effects table and the Tsunami Sources table. Arrange the two tables next to each other so that you can compare the dates in the two tables.  

By comparing the two tables, determine which Tsunami Sources caused Tsunami Effects in more than one location. Leave the tables open for the next question.


The earthquake in the Mediterranean Sea in 1303 affected 1 location in Egypt.
The earthquake off Portugal in 1755 affected 2 locations in Morocco and Algeria.
The earthquake in the S Java Sea in 1883 affected 2 locations in South Africa.
The earthquake off Trinidad in 1911 affected 2 locations in Ghana and Togo.

The earthquake off the Gold Coast in 1939 affected 1 location in Ghana.  

The earthquake in Congo in 1957 affected 1 location in Congo.
Question 8 Which tsunamis actually caused some type of damage? 

1303 - Alexandria

1755 - Safi Morocco

1911 - Lome, Gold Coast
Question 9 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.  

1957 - Kivu, Congo

 
Question 10

How do you know that this was a seiche rather than a tsunami?

 

The earthquake and the tsunami were hundreds of miles from the coast. 

 

 
*** End of Activity 6 ***

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U.S. Department of the Interior
U.S. Geological Survey
Rocky Mountain Mapping Center
URL:http://rockyweb.cr.usgs.gov/outreach/africa/act6_answers.html
Last modified:   18 May 2004