Volcanic Activity Along Mid-Atlantic Ridge

The Mid-Atlantic Ridge is a significant underwater mountain range, formed by plate tectonics where the North American and Eurasian plates are pulling apart (divergent boundary). This process is known as sea-floor spreading.

Analyzing Assertion (A)

• Assertion (A) states that islands along the Mid-Atlantic Ridge are highly prone to volcanic activity.
• At divergent boundaries like the Mid-Atlantic Ridge, magma from the Earth's mantle rises to fill the gap created by separating plates.
• This rising magma leads to volcanic eruptions, forming islands such as Iceland and the Azores, which are situated on the ridge.
• Therefore, Assertion (A) is factually correct.

Analyzing Reason (R)

• Reason (R) claims that sea-floor spreading is the main cause of earthquakes in the Atlantic Ocean.
• Sea-floor spreading involves the movement and fracturing of the Earth's crust as plates diverge.
• The tectonic stresses and movement along the Mid-Atlantic Ridge generate numerous earthquakes, making sea-floor spreading a primary cause of seismic activity in the Atlantic.
• Therefore, Reason (R) is factually correct.

Evaluating the Explanation

• The question asks if Reason (R) correctly explains Assertion (A).
• Sea-floor spreading is the fundamental process occurring at the Mid-Atlantic Ridge.
• This spreading involves the upwelling of magma, which directly causes volcanic activity (Assertion A).
• Simultaneously, the tectonic forces and crustal adjustments during sea-floor spreading cause earthquakes (Reason R).
• Thus, the mechanism of sea-floor spreading inherently links both volcanic activity and earthquakes in this region.

Conclusion

Both Assertion (A) and Reason (R) are true statements. Furthermore, the process described in Reason (R) (sea-floor spreading) is the direct geological mechanism causing the volcanic activity described in Assertion (A).

Therefore, Reason (R) is the correct explanation of Assertion (A).