MCQ 1. With reference to the Afar Triple Junction, consider the following statements:
1. It is the only place on Earth where three divergent plate boundaries meet on land.
2. It marks the junction of the Arabian Plate, Nubian Plate, and Somali Plate.
3. It is associated with the formation of a new ocean basin.
Select the correct answer:
A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2 and 3
Explanation:
• All three boundaries in Afar Rift (Red Sea Rift, Gulf of Aden Rift, East African Rift) are divergent → Statement 1 correct.
• The three plates involved are Arabian + Nubian (African) + Somali → Statement 2 correct.
• The region is slowly splitting Africa, creating a future ocean → Statement 3 correct.
• All three boundaries in Afar Rift (Red Sea Rift, Gulf of Aden Rift, East African Rift) are divergent → Statement 1 correct.
• The three plates involved are Arabian + Nubian (African) + Somali → Statement 2 correct.
• The region is slowly splitting Africa, creating a future ocean → Statement 3 correct.
MCQ 2. The Afar region of Ethiopia is geologically important because it is the only major continental area where:
A) A subduction zone is forming inside a continent
B) Active rifting, sea-floor spreading, and volcanism occur simultaneously
C) Two continental plates collide
D) Strike-slip faulting dominates over extension
Explanation:
Afar = active continental rifting + incipient sea-floor spreading + volcanism, all in one place.
Afar = active continental rifting + incipient sea-floor spreading + volcanism, all in one place.
MCQ 3. Hayli Gubbi volcano is best classified as which type?
A) Stratovolcano formed at convergent boundaries
B) Shield volcano formed due to basaltic fissure eruptions
C) Caldera volcano formed by explosive rhyolitic eruptions
D) Mud volcano formed by sediment-gas reactions
Explanation:
Ethiopian volcanoes in the Afar region are broad, basaltic, shield-type volcanoes associated with mantle plume + rifting.
Ethiopian volcanoes in the Afar region are broad, basaltic, shield-type volcanoes associated with mantle plume + rifting.
MCQ 4. Consider the following pairs: Volcano Region – Tectonic Setting
1. Nabro (Eritrea) – Divergent boundary
2. Nyiragongo (DRC) – Divergent boundary
3. Erta Ale (Ethiopia) – Hotspot and rift-related volcanism
Which of the pairs are correctly matched?
A) 1 and 3 only
B) 1 and 2 only
C) 2 and 3 only
D) 1, 2 and 3
Explanation:
• Nabro → in Afar = divergent (correct).
• Nyiragongo → NOT divergent; it is within the Western Rift but fed by deep plume → pair 2 incorrect.
• Erta Ale → hotspot + rifting → correct.
• Nabro → in Afar = divergent (correct).
• Nyiragongo → NOT divergent; it is within the Western Rift but fed by deep plume → pair 2 incorrect.
• Erta Ale → hotspot + rifting → correct.
MCQ 5. Which of the following characteristics are typical of shield volcanoes?
1. High viscosity magma
2. Low angle slopes
3. Frequent effusive eruptions
4. Formation mainly from basaltic lava
Choose the correct answer:
A) 1, 2 and 3
B) 2, 3 and 4
C) 1 and 4
D) 1, 3 and 4
Explanation:
Shield volcano = low viscosity, basaltic, gentle slopes, effusive lava.
Shield volcano = low viscosity, basaltic, gentle slopes, effusive lava.
MCQ 6. The East African Rift System (EARS):
A) Is caused by two plates colliding
B) Represents active continental breakup
C) Is older than the Himalayas
D) Has no volcanic activity
Explanation:
EARS = active continental breakup; volcanism is widespread.
EARS = active continental breakup; volcanism is widespread.
MCQ 7. Plate boundary divergence in Afar is primarily driven by:
A) Slab pull
B) Ridge push
C) Mantle plume upwelling
D) Transform faulting
Explanation:
Afar = influenced strongly by African Superswell and Afar mantle plume → uplift + rifting..
Afar = influenced strongly by African Superswell and Afar mantle plume → uplift + rifting..
MCQ 8. Which of the following best explains why volcanoes in Ethiopia have basaltic composition?
A) Melting of subducting oceanic crust
B) Decompression melting due to rifting
C) High silica content in continental crust
D) Plate collision-induced melting
Explanation:
Rifting causes decompression melting, producing basaltic magma.
Rifting causes decompression melting, producing basaltic magma.
MCQ 9. Which African region is most likely to become a new ocean in future geological timescales?
A) Sahel Belt
B) Congo Basin
C) Afar–Somali region
D) Sahara Desert
Explanation:
The Somali Plate is separating → forming new ocean basin.
The Somali Plate is separating → forming new ocean basin.
MCQ 10. In the Afar Triangle, faulting is predominantly:
A) Reverse
B) Strike-slip
C) Normal
D) Thrust
Explanation:
Rifting → extensional forces → normal faults.
Rifting → extensional forces → normal faults.