Why are so many volcanoes found on the ring of fire around the margin of the pacific ocean?

The Ring of Fire runs along the borders of the Pacific ocean.

Explanation:

The Ring of Fire is also known as the Circum-Pacific Belt. It is a line of volcanos (and subsequent earthquakes) that surrounds the Pacific Ocean; this is where the majority of earthquakes and volcanic eruptions on Earth occur.

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answer at the divergent plate boundary in the middle of the ocean;