Subduction Zone
Where one tectonic plate slides beneath another, producing the planet's largest earthquakes.
A subduction zone is a boundary where one tectonic plate dives beneath another into the mantle. These zones produce the largest earthquakes on Earth, including every recorded event above magnitude 9.
The descending plate locks against the overriding one for centuries, building strain that releases in a sudden megathrust rupture. Subduction zones ring the Pacific in the Ring of Fire and account for events like the 1960 Chile magnitude 9.5, the 2004 Sumatra magnitude 9.1, and the 2011 Tohoku magnitude 9.1. They also tend to produce the tsunamis that cause the most distant damage.
Related terms
Magnitude
A number describing the energy an earthquake released at its source, on a logarithmic scale.
Hypocenter Depth
How far below the surface an earthquake's rupture began, which shapes how hard the surface shakes.
Fault
A fracture in the Earth's crust where blocks of rock move past each other, releasing quakes.