Geomorphology of the Pacific

The drawing above illustrates the phenomenon of plate tectonics discussed on the Geography page of SouthPacific.org. East of Fiji, the Indo-Australian Plate faces the Pacific Plate with the Tonga Trench between the two. To the north, the Pacific Plate is separated from the Eurasian Plate by the Marianas Trench. The islands east of these trenches are largely volcanic or coralline while those to the west are more likely to be continental. Friction along the Pacific `Ring of Fire` between the plates causes earthquakes and volcanic eruptions and the flexing makes islands rise or fall. As volcanoes sink, coral accumulates converting high islands into atolls. Of course, this is a very simplified glimpse of a complicated subject.