Plate Tectonics And Distribution Of Volcanoes Flashcards
What is the tectonic cycle
Is the constant formation and destruction of the earths crust
What is plate tectonic theory
Describes how the earths lithosphere is split into large slabs called plates that move because of heat from the earths core causing upper mantle to move in huge slow moving convection currents which drag plates and cause them to collide, separate and slide past each other
Where do volcanoes occur
Where plates collide and separate and hotspots
Where are constructive boundaries found
Mostly under the ocean
What plates are separating to form Mt Hekla in Iceland
Eurasian and North American plate
What is the long split called that separating plates form
Rift valley
What is a mid ocean ridge
Is a long ridge of volcanic mountains formed from magma rising through rift and cooling on surface - e.g Mid Atlantic Ridge
What volcano forms at destructive plate boundaries
Mount Fuji Japan
What two oceanic plates collide
The pacific and Philippines - the pacific plate sinks and subducts
What is subduction
When a plate sinks beneath another plate and is absorbed back into the mantle - less dense than the mantle
How are volcanic island arcs formed
When recycled material from plates rises through cracks in crust until it reaches the surface through the vent - they are curved chains of volcanic islands which mark subduction zones
What type of magma is at destructive boundaries
Very acidic magma which forms steep-sided volcanic cones - Mount Pinatubo in Philippine islands
Example of a hotspot
Hawaiian islands of the pacific
What is a hotspot
Sometimes magma from the mantle is able to reach the surface of the earth in the middle of the plate as a fountain or plume of magma rises to the surface and forces through the crust
What type of volcano forms at hotspots
Shield volcanoes with basic magma
