1.   This pattern coincides with a number of structural features, including mid-oceanic ridges, mountain belts, oceanic trenches and volcanic island arcs.

2.   The second category is closely related to oceanic trenches and their associated island arcs or mountain belts.

3.   Convergent boundaries between oceanic lithosphere are marked by an oceanic trench, a volcanic island arc and a Wadati-Benioff zone.

4.   As with an intra-oceanic island arc the oceanward side of a continental-margin orogen is marked by an oceanic trench associated with the downgoing oceanic lithosphere.

5.   Across the Sunda Arc there is a distinct sequence of oceanic trench, outer-arc ridge, forearc basin, volcanic-arc and back-arc zone.