Why are there so many volcanoes near Seattle WA?

Answer 1

Because the Pacific Ocean tectonic plate is still spreading from the East Pacific Oceanic ridge while being subducted underneath at least 6 major and minor

tectonic plates

,

North American

, South American, Indian-Australian, Indonesian, Caribbean, and Antarctic. Subduction produces volcanism when subducted basaltic oceanic crust melts at 700 km or more in the mantle and the magma rises because of density differences to be erupted in volcanoes creating volcanic arcs in either the ocean, like Japan and the

Philippine Islands

and Indonesia and New Zealand, or on land, like the Andes and the Cascade and Olympic mountain. The San Andreas and associated fault systems are a transform fault system that form part of the Ring of Fire system East Pacific Rise spreading system.

Answer 2

Washington sits on the pacific ring of fire the world most volcanically active area