Oceanic–Oceanic Convergent Boundaries Vocabulary

Vocabulary flashcards covering essential terms and concepts related to oceanic–oceanic convergent boundaries, their geology, and associated hazards.

Oceanic–Oceanic Convergence

A tectonic boundary where two oceanic crustal plates move toward each other and collide, forcing one plate to subduct beneath the other.

Subduction

The process in which the denser of two converging oceanic plates is forced downward into the mantle beneath the overriding plate.

Downgoing Plate

The oceanic plate that bends and plunges beneath another plate at a trench during subduction.

Mariana Trench

A crescent-shaped trench in the western Pacific, about 200 km east of the Mariana Islands, formed by Pacific Plate subduction and reaching depths of 10,916 m at Challenger Deep.

Challenger Deep

The deepest point on Earth (≈10,916 m/35,814 ft) located within the Mariana Trench.

Trench Rollback

The eastward migration of the Mariana Trench caused by the Pacific Plate ‘rolling back’ as it is subducted.

Ogasawara Plateau

Structure that pins the northern end of the Mariana Trench, restricting further trench migration.

Caroline Ridge

Ridge that pins the southern end of the Mariana Trench, contributing to its banana-shaped curvature.

Volcanic Island Arc

A curved chain of volcanic islands forming on the overriding plate parallel to an oceanic trench, e.g., the Mariana and Aleutian Islands.

Back-Arc Basin

An ocean basin that develops behind a volcanic arc; the Mariana system hosts one of the youngest examples.

Aleutian Trench

A 3,400 km-long trench south of Alaska where the Pacific Plate subducts beneath the North American Plate, classified as a marginal trench in the east.

Marginal Trench

A trench running along the margin of a continent, as seen in the eastern Aleutian Trench.

Forearc Basin

A relatively shallow marine basin situated between an oceanic trench and its related volcanic arc.

Accretionary Wedge

Chaotic mass of sediments and crust scraped off the subducting plate and piled against the overriding plate at a convergent margin.

Megathrust Earthquake

A powerful quake generated at the interface of a subducting and overriding plate, common in oceanic–oceanic subduction zones.

Tsunami

Large sea waves produced by sudden seafloor displacement during megathrust earthquakes in trenches such as the Aleutian.

Hydrothermal Vent

Hot, mineral-rich seafloor spring found in subduction settings like the Mariana region, home to exotic life forms.

Mud Volcano

Submarine volcanic feature extruding mud; the Mariana region hosts some of the largest on Earth.

Pacific Plate

The oceanic plate subducting beneath both the Mariana system and the Aleutian arc.

North American Plate

The overriding plate above the subducting Pacific Plate along the Aleutian Trench.

Volcanic Activity

Eruptions and magma generation resulting from melting of the subducted plate, exemplified by Mount Cleveland and Shishaldin in the Aleutians.

Plate-Tectonic Hazards

Earthquakes, volcanic eruptions, and tsunamis that arise from oceanic–oceanic convergence, affecting human communities and infrastructure.