Plate Boundaries and Hazards

Divergent Plate Boundaries

plates move apart

• associated with earthquakes and volcanic eruptions (basaltic, not explosive)

• decompression melting

Transform Fault Boundaries

plates slide past each other horizontally (ex: san andres fault)

• great earthquake hazard

• strike-slip faults

Convergent Plate Boundaries

plates collide (subduction zones and continent-continent)

Subduction Zones

denser oceanic plate goes underneath an oceanic or continental plate (less dense)

• associated with explosive volcanoes (andesitic or rhyolitic); severe landslides, earthquakes, mudflows, ash flows too (more than 80% subaerial eruptions)

• water from subducting plate causes mantle melting

• composite cones and stratovolcanoes

Continent-continent

collision zone

• crust too low in density to subduct

• associated with earthquakes and high topography (mountains), affecting climate