Mariana Trough
active back-arc basin in the western Pacific Ocean
The Mariana Trough is an active back-arc basin in the western Pacific Ocean (Stern, Fouch & Klemperer 2003). It is an integral part of the Izu–Bonin–Mariana Arc system.
Location and Bathymetry
The Mariana Trough stretches 1300 km from north to south, about the distance from Los Angeles CA to Portland OR, Tokyo, Japan to Seoul, Korea, or London, England to Rome, Italy. The Mariana Trough has roughly the dimensions and areal extent of Japan or California. The Trough is crudely crescent-shaped, opening on the south; it is bounded to the east by the active Mariana arc, to the west by the remnant arc of the West Mariana Ridge (Karig 1972), and to the south by the Challenger Deep, part of the Mariana Trench. It narrows northward until the Mariana arc and West Mariana Ridge meet at about 24°N. It is widest in the middle, at 18°N, where it is about 240 km wide, and narrows to about half this at its southern, open end. Depths in the basin are distributed asymmetrically, being greater adjacent to the West Mariana Ridge than next to the active arc, due to a westward-thinning wedge of volcaniclastic sediments derived from the active arc, and also less thermal buoyancy of the mantle. Where not covered by sediments, the seafloor is deeper and bathymetry more rugged than normal. The most recent, "zero-age" seafloor of the Philippine Sea, including the Mariana Trough, lies at a mean depth of 3200 m compared to normal zero-age seafloor depths of 2500 m (Park, Tamaki & Kobayashi 1990).
Extension style
The extension axis for the Mariana Trough can be subdivided along strike into a southern two-thirds characterized by slow seafloor spreading and a northern third characterized by rifting.
The public source identifies “Mariana Trough” as active back-arc basin in the western Pacific Ocean. This brief keeps that definition visible, then builds a research path around Mariana, Trough and active.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Mariana Trough”, the useful work is to connect “active back-arc basin in the western Pacific Ocean” to the records capable of establishing context and consequence.
Maps, plans, fabric surveys and administrative records can establish how the site’s name, extent and function changed over time. The source revision retrieved here is dated Dec 28, 2025. The linked authority identifier is Q6762070. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2003, 1300, 1972 and 1990.
Architectural summaries often privilege surviving fabric and can understate demolished phases, contested use or displaced communities. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
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Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
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Questions for further research
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This entry incorporates text from “Mariana Trough” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.