WadatiBenioffi

The Wadati–Benioff zone, sometimes spelled Wadati–Benioffi, is a planar zone of earthquakes that defines the descending slab in a subduction zone. The term honors Kiyoo Wadati and Hugo Benioff, who independently studied the pattern of deep earthquakes and recognized a dipping zone of seismicity extending from the trench to depths of several hundred kilometers.

Seismicity within the zone extends from shallow crustal events near the trench to deep-focus earthquakes reaching depths of about 700 kilometers or more within the subducting plate. The earthquakes typically align on a near-vertical to moderately dipping plane that traces the geometry of the subducting slab.

Geophysical significance: The Wadati–Benioff zone provided crucial evidence for plate tectonics, showing how oceanic lithosphere sinks into the mantle. Its observation helped map the geometry of subduction zones and proffered explanations for the origin of deep-focus earthquakes, which occur at depths beyond the brittle failure of rock.

Hazard and research: Understanding the zone informs seismic hazard assessment along subduction margins, including interplate and intraplate processes. The study of the zone continues to illuminate slab dehydration, mineral phase changes, and mantle rheology that influence earthquake behavior.