RAS question
The seismicity of Northeast India is primarily due to its proximity to which tectonic boundary?
Correct answer: (C) Collision zone between the Indian and Eurasian tectonic plates.
The seismicity of Northeast India is primarily linked to the collision zone between the Indian and Eurasian tectonic plates.
Explanation
Northeast India lies in Seismic Zone V because it is close to the collision zone between the Indian and Eurasian tectonic plates, so it falls within India's highest seismic-hazard category. The Ministry of Earth Sciences' Lok Sabha reply says the Indian sub-continent is among the world's most earthquake-prone areas, with earthquakes along the Alpine-Himalayan belt, including the Indo-Burmese and Himalayan arcs. It further attributes these earthquakes to the continued collision or subduction of the Indian plate with the Eurasian and Sunda plates. Option C is therefore the best fit because it identifies the relevant convergent plate setting, rather than an unrelated oceanic or Pacific boundary.
Why the other options are wrong
- (A) A divergent Indian-Australian boundary describes plate separation, while Northeast India's seismicity is linked to collision involving the Indian and Eurasian plates.
- (B) A Pacific Ring of Fire transform boundary is not the tectonic setting named for Northeast India by the MoES reply.
- (D) The Pacific Plate subduction zone is outside this tectonic setting; the cited cause here is the Indian plate's interaction with the Eurasian and related plate setting.
Concept
This tests the Indian geography concept of seismic zoning as an outcome of plate tectonics. It recurs in RAS because Northeast India is a standard case for linking earthquake hazard with India's active tectonic margins.