GeologyLesson 3 of 4 in the course Plate tectonics

Subduction: Slab Dynamics, Arc Formation, Hazards, and Earth-System Effects

5 flashcards · 5 quiz questions · 5 match pairs · 3 fill-in sentences · English

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Summary

Subduction recycles lithosphere into the mantle and helps drive plate motion. This lesson introduces the process, the materials involved, and the forces that make it possible.

Subduction is the sinking of one tectonic plate beneath another at a convergent plate boundary. The descending part of the plate is called the slab. It carries oceanic crust, uppermost mantle, sediments, and some water into the mantle, where these materials are recycled.

All flashcards

What is a subducting slab?
The portion of a tectonic plate that descends into the mantle.
What is negative buoyancy?
The tendency of material denser than its surroundings to sink under gravity.
What is slab pull?
The pull exerted on a plate by its sinking, negatively buoyant slab.
What is flux melting?
Melting promoted when added water lowers the melting temperature of mantle rock.
What is a Wadati–Benioff zone?
An inclined band of earthquakes that follows a descending slab.

Quiz questions

  1. What does a Wadati–Benioff zone reveal about a subduction zone?Answer: Earthquakes occur along an inclined band following the descending slab.
  2. What can flat-slab subduction do to volcanism above the nearly horizontal part of a slab?Answer: It can create a volcanic gap above that part of the slab.
  3. How does water released from a subducting slab promote magma formation?Answer: It lowers the melting temperature of mantle rock above the slab.
  4. How can a megathrust earthquake generate a tsunami?Answer: Rapid seafloor displacement moves a large volume of seawater.
  5. What is spontaneous initiation of subduction?Answer: A sufficiently dense plate founders and sinks beneath a neighboring plate.

Based on the Wikipedia article Subduction, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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