Question

Which one of the following reasons best explains the occurrence of large number of earthquakes at the active plate boundaries compared to the plate interiors?

• A. Strain energy accumulation is higher at the plate boundaries
• B. Stiffness is higher at the plate boundaries
• C. Heat flow is lower at the plate boundaries
• D. Crust is thinner at the plate boundaries

Hint:

Most seismic activity occurs at plate boundaries due to the accumulation and release of strain energy during plate movements.

Answer 1

The Correct Option is A

Step 1: Understanding earthquake distribution.
Earthquakes are most commonly associated with the movement of tectonic plates at their boundaries, where plates interact through convergent, divergent, or transform boundaries. These regions are typically more seismically active due to the ongoing plate movements.

Step 2: Analyzing strain energy accumulation.
At plate boundaries, large amounts of strain energy accumulate as plates move, either colliding, sliding past, or moving away from each other. When this strain is released, it results in seismic activity (earthquakes). Hence, strain energy accumulation is higher at the plate boundaries compared to the interior, where tectonic activity is more limited.

Step 3: Analyzing option (B) – Stiffness.
Stiffness refers to the resistance of rocks to deformation. While the stiffness of rocks might influence the type of earthquakes (e.g., brittle vs. ductile), it does not directly explain why plate boundaries experience more earthquakes. This makes option (B) less relevant.

Step 4: Analyzing option (C) – Heat flow.
Heat flow is generally higher at plate boundaries due to tectonic activity, and lower heat flow is typically associated with plate interiors. However, the main cause of earthquake activity at plate boundaries is strain accumulation rather than heat flow. Therefore, option (C) is not the best explanation.

Step 5: Analyzing option (D) – Crust thickness.
While the crust is generally thinner at plate boundaries compared to plate interiors, this factor alone does not fully explain the increased seismic activity. The primary factor is the accumulation of strain energy.

Step 6: Conclusion.
The best explanation for the higher frequency of earthquakes at plate boundaries is that strain energy accumulation is higher at the plate boundaries, making option (A) the correct answer.
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