Two volcanic regions are located in different tectonic settings: Region X lies above a subduction zone. Region Y sits over a hotspot in an oceanic plate. Both regions experience volcanic activity, but their eruptions differ significantly in style and structure. Which explanation best accounts for the difference in eruption style between Region X and Region Y?

At a subduction zone, water and other volatiles from the descending plate enter the mantle and contribute to magma formation. This magma is often more viscous and gas-rich, so pressure can build and eruptions can be explosive. An oceanic hotspot typically produces dry, basaltic magma that flows more easily, favoring gentler eruptions. Thus, the magma source and resulting magma properties best explain the difference.

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