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This unusual 3-D view of the northwestern Pacific Ocean Basin and northeastern Asia was created using ocean bathymetry (i.e., depth) data and surface topography data from the National Geophysical Data Center. These data were reprocessed to produce two shaded-relief topographic models of the ocean floor from two different perspectives. These images have been combined to give us a 3-D view of part of the seafloor, which covers 70% of the Earth’s surface but cannot be seen directly. The geology of the western Pacific region is dominated by plate tectonics. Earth’s outer crust is divided into a series of large plates. The Pacific plate (forming the ocean floor) is being subducted or thrust beneath the Eurasian plate (to the upper left), forming a series of connected arcuate deep sea trenches and associated volcanic island arcs that nearly circle the Pacific Ocean. These subduction zones are sources of volcanism and earthquakes and together form the “Ring of Fire.” The subduction process is unique to Earth (with the possible exception of several arcuate structures on Venus). At the same time, new crustal material is continually being formed at mid-ocean ridges. Island arcs parallel ocean trenches and form when heat in the Earth’s mantle partially melts the descending plate. This molten material rises as magma, forming arcuate chains of volcanos, such as the Kurile Island and Aleutian Island arcs (upper center and upper right, respectively). Mount St. Helens (slide #8) and Klyuchevskaya (slide #9) are examples of these volcanos. The large arcuate mountain range at center left is Japan, which is a volcanic arc formed over a fragment of continental crust. The seafloor is also dotted by numerous volcanic seamounts. The Emperor Seamount chain extends along center right. Image Width: ~6500 kilometers Right click here to download a high-resolution version of the image (465 KB)
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