A) [Countries with high population densities 6-9, and also at risk from earthquakes and volcanoes: Ethiopea, Kenya, Rwanda, Burundi, Uganda, Nigeria, and Mozambique.]
B) [Nyamuragira Volcano last erupted in 1996.]
C) [Ethiopia has the most historic volcanoes.]
D) [Rwanda is most at risk from erupting volcanoes – it has 3.]
This map of East Africa shows some of the historically active volcanoes (red triangles) and the Afar Triangle (shaded, center) -- a so-called triple junction (or triple point), where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian and the Somalian) splitting along the East African Rift Zone.
In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. The actively splitting African Plate and the Arabian Plate meet in what geologists call a triple junction, where the Red Sea meets the Gulf of Aden. A new spreading center may be developing under Africa along the East African Rift Zone. When the continental crust stretches beyond its limits, tension cracks begin to appear on the Earth's surface. Magma rises and squeezes through the widening cracks, sometimes to erupt and form volcanoes. The rising magma, whether or not it erupts, puts more pressure on the crust to produce additional fractures and, ultimately, the rift zone. For more information, visit: http://pubs.usgs.gov/publications/text/understanding.html
*** End of Activity 5 for ArcView Answer Key ***
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