Plate Boundary Types

There are three overarching types of plate boundaries:

  1. Convergent boundaries where plates collide, one slides beneath the other, and surface area on Earth is consumed.
  2. Divergent or rift boundaries where plates separate and new lithosphere is created in the gap to generate planetary surface area.
  3. Transform boundaries where plate slide past each other and no (or very little) new surface area is created or destroyed.

In Earth Observer's map we have used the synthesis of Bird (2003) and subdivided these three types into seven classes according to whether the lithosphere that makes up the plates at the plate boundary is continental or oceanic.

Seven classes of plate boundaries:

  • OTF - Ocean Transform Fault
  • OCB - Ocean Convergent Boundary
  • OSR - Ocean Spreading Ridge
  • CCB - Continental Convergent Boundary
  • CTF - Continental Transform Fault
  • CRB - Continental Rift Boundary
  • SUB - Subduction
  • A subduction bcoundary is where oceanic lithosphere belonging a converging plate slides under either continental lithosphere of the adjacent colliding plate or an island arc on the adjacent plate. Note that many plates consist of both oceanic and continental lithosphere.
    Plate Boundary Length
    The total length of Earth's present-day plate boundaies is 260,000 km or some 6.5 times lonnger than the Earth's circumference at its equator. Although the plate boundareies have commonly been compared to seams on a baseball, in reality the pattern is much more elaborate with seams of much greater length and complexity.

    Plate Boundaries classes ranked in order of length (km) and by relative percent of total plate boundary length:

  • OSR - Ocean Spreading Ridge - 67,300 km (25.8%)
  • SUB - Subduction - 51,310 km (19.7%)
  • OTF - Ocean Transform Fault - 47,800 km (18.3%)
  • CRB - Continental Rift Boundary - 27,500 (10.5%)
  • CTF - Continental Transform Fault 26,100 km (10.0%)
  • CCB - Continental Convergent Boundary - 23,000 km (8.8%)
  • OCB - Ocean Convergent Boundary - 17,500 km (6.7%)
  • The plate boundary of greatest total length belongs to the ocean spreading ridge class. Here which the vast majority of new planetary surface area is created as oceanic lithosphere. The total length of subduction type plate boundaries is second in rank to the ocean spreading ridge. This somewhat smaller length requires that Earth's surface area must be consumed at subduction type boundaries at a faster rate than it is created at ocean spreading ridges.

    Data Source:
    Bird, P. (2003) An updated digital model of plate boundaries, Geochemistry Geophysics Geosystems, 4(3), 1027, doi:10.1029/2001GC000252.

    Further Reading: