hazards -how do plates move Flashcards
how many theory’s are there that explain how plates move?
3
what are the 3 theory’s to how plates move?
.convection currents
.ridge push
.slab pull
what helps to create convection currents?
.higher temperatures from the Earth’s core, and heat released by radioactive decay of elements within the mantle
where do convection currents occur?
.in the asthenosphere
what do convection currents do?
.transfer heat from the core to the earth surface
what causes the continuous circulator motion in the asthenosphere?
.zones of hotter, more liquid magma exhibit a continuous circulatory motion
where does ridge push occur?
.occurs at mid-oceanic ridges at constructive plate margins
how does ridge push create plate movement?
.hot magma rises to the surface and heats surrounding rocks
.these expand and become elevated above the sea floor forming a slope .as new rock forms it cools and becomes denser
.gravity then causes it to slide down the slope, away from the mid-ocean ridge
what results from gravity causing new rock to slide down, away from the mid-ocean ridge?
.sea floor spreading
what happens where the sea floor spreads?
.new crust is formed through volcanic activity causing the plates to move apart from each other
where does slab pull occur?
.destructive plate margin
how does slab pull cause plate movement?
.subducting ocean plate is denser than the surrounding material so as the plate begins to sink into the mantle it pulls the rest of the plate behind it
what evidence is there that suggests there may be more than one force for plate movement?
.plates move at their own rate, which suggests that it could involve a combination of forces
