 Effects of plate movement : Earthquakes, Volcanoes, Tsunamis
Mountains, Sea-floor spreading, and Mid-ocean Ridges
 There are 3 types of plate boundaries : Convergent (plates move
towards each other), Divergent (plates move away from each
other), and Transform (plates slide past each other)
 All boundaries produce earthquakes
 Volcanoes form at divergent and convergent boundaries
 Seafloor spreading and Mid-Ocean ridges form at divergent
boundaries
 There are 3 types of CONVERGENT boundaries: OceanicOceanic, Oceanic-Continental, Continental-Continental
 Subduction zones (where one plate subduct—slides under—
another) occur at convergent boundaries involving one or more
oceanic plates.
 Oceanic-Oceanic convergent boundaries produce underwater
volcanoes, trenches, volcanic islands, and earthquakes.
 Oceanic-Continental convergent boundaries produce
volcanoes/volcanic mountains, trenches, and earthquakes.
 Continental-Continental convergent boundaries produce folded
mountains/mountain ranges, high plateaus, and earthquakes
 Transform boundaries produce earthquakes only.
 Each boundary type produces it’s own type of fault:
Divergent produces a normal fault
Convergent produces a reverse fault
Transform produces a strike-slip fault
The most famous transform boundary and strike slip fault is the
San Andreas Fault, which runs through California and Mexico for
about 800km (500mi)
 At each type of fault or boundary there is a different type of stress
(a force that is applied to the plates or rock):
There are 3 types of stress forces: Tension, Compression, and
Shear
 Tension is when the rock is pulled apart or stretched
 Compression is when rock is squeezed or pushed together until it
is folded or breaks
 Shear is when rock moves in opposite directions and breaks