arc-trench gap

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arc-trench gap (fore-arc) The region between an oceanic trench and the adjacent volcanic island arc. The arc-trench gap is at least 100 km wide in nearly all cases, and up to 570 km at the eastern end of the Aleutian arc. The width of the arc-trench gap increases with time through the growth of an accretionary wedge and the development of a fore-arc basin.