How do subduction zones contribute to both earthquake and volcanic hazards in nearby regions?

• A. Subduction zones host megathrust earthquakes causing tsunamis and magmatic arcs that can erupt volcanically
• B. They never produce volcanoes
• C. They prevent earthquakes
• D. They reduce hazard by absorbing energy

Answer: (A)

Subduction zones generate both large earthquakes and volcanic activity because one tectonic plate sinks beneath another, creating intense friction and melting processes that drive hazards in nearby regions. The stuck plates accumulate elastic energy until they rupture in megathrust earthquakes, which can shake the ground violently and displace the seafloor, often triggering tsunamis that threaten coastlines. At the same time, fluids released from the descending slab lower the melting point of the overlying mantle, producing magma that rises to form volcanic arcs along the overriding plate; those eruptions can be highly explosive and affect nearby populations and air travel.

So these regions pose a dual risk: powerful ground shaking from megathrust earthquakes and volcanic eruptions from the associated magma activity. The idea that subduction zones either never produce volcanoes, or prevent earthquakes, or simply absorb energy to reduce hazards, doesn’t hold because the very processes at work—slab dehydration, mantle melting, frictional locking, and sudden rupture—drive both seismic and volcanic hazards.