deep-focus earthquake

seismology

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June 25, 2026

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Deep-focus earthquakes originate deeper within the Earth than shallow or intermediate ones, typically at depths between 300 and 700 km (186 to 430 miles). While most earthquakes are shallow, a small percentage of the total energy released comes from intermediate and deep-focus quakes. These deeper earthquakes often occur in patterns known as Benioff zones, which are associated with subducting tectonic plates. These zones are commonly found along island arcs and ocean trenches. The study of earthquakes, known as seismology, uses seismic waves to understand these phenomena.12

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earthquake
Shallow, intermediate, and deep foci
The deeper-focus earthquakes commonly occur in patterns called Benioff zones that dip into the Earth, indicating the presence of a subducting slab. Dip angles of these slabs average about 45°, with some shallower and others nearly vertical. Benioff zones coincide with tectonically active island arcs such…
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The deeper-focus earthquakes commonly occur in patterns called Benioff zones that dip into the Earth, indicating the presence of a subducting slab. Dip angles of these slabs average about 45°, with some shallower and others nearly vertical. Benioff zones coincide with tectonically active island arcs such…
Read More