Q. Consider the following statements regarding regional tectonic volcanic zones:
1.The East African Rift represents a major continental divergence zone where active volcanoes like Mount Kilimanjaro and Mount Kenya are located.
2.The volcanic arc of the Andes Mountains is created by the subduction of the Nazca Plate beneath the overriding South American Plate.
3.The high density of active volcanoes in the Indonesian Archipelago is primarily driven by the shallow transform faulting between the Indian-Australian and Pacific plates.
4.The Aleutian volcanic arc in Alaska belongs directly to the Mid-Atlantic Ridge tectonic system, formed via the rifting of the Arctic crust.
Which of the statements given above are correct?
Answer: A
Notes:
Explanation::
- Statement 1 is correct: The East African Rift is an active continental rift valley system where the African Plate is splitting into the Somali and Nubian sub-plates. This extension allows magma to breach the continental crust, forming massive isolated volcanic peaks like Kilimanjaro and Mount Kenya.
- Statement 2 is correct: The Western margin of South America is a classic convergent boundary. The oceanic Nazca Plate subducts beneath the continental South American Plate, melting the lower crust and fueling the extensive volcanic chain of the Andes.
- Statement 3 is incorrect: Indonesia’s high volcanic density is driven by subduction zones (convergent boundaries) where the Indo-Australian plate subducts beneath the Sunda/Eurasian plate, not by transform (horizontal sliding) faulting.
- Statement 4 is incorrect: The Aleutian volcanic arc in Alaska is located in the northern Pacific Ocean and forms a segment of the Pacific Ring of Fire, not the Mid-Atlantic Ridge. It is formed by the subduction of the Pacific Plate under the North American Plate.
