Hazards - Plate tectonics Flashcards
What is the inner core?
a solid ball of iron/nickel. It is very hot due to pressure and radioactive decay, responsible for the earth’s internal energy
What is the outer core?
semi-molten, made up of iron and nickel
What is the mantle?
mainly solid rocks, high in silicon. made up of the asthenosphere and the lithosphere
What is the asthenosphere?
semi-molten layer constantly moving die to convection currents, movements powered by the heat from the core, it is underneath the lithosphere
What is the lithosphere?
broken up into plates, majority within the mantle, the top of it is the crust
What is the crust?
a thin top layer of the lithosphere, both oceanic and continental crust
What is Plate tectonic theory?
the lithosphere is broken up into large slabs of rock called tectonic plates. These move due to convection currents in the asthenosphere
What happens at a destructive plate margin (continental and oceanic)?
- denser oceanic plate is subducted
- leaves a deep ocean trench
- fold mountains are formed
- magma causes pressure to build up causing explosive composite volcanoes
What happens at destructive plate margins (oceanic and oceanic)?
- heavier plate is subducted, leaving an ocean trench and fold mountains to occur
- the built up pressure causes underwater volcanoes
- lava cools, creating island arcs
What happens at destructive plate margins (continental and continental)?
- pressure builds
- no subduction occurs
- pile up of continental crust creates fold mountains
What happens at constructive plate margins (oceanic and oceanic)?
- magma rises in between the gap left by the two plates separating, forming new land
- less explosive underwater volcanoes formed
- new land forming on the ocean floor (sea floor spreading)
What happens at constructive plate margins (continental and continental)?
- any land in the middle of the separation is forced apart causing a rift valley
- volcanoes form when magma rises
- the gap is (potentially) filled with water
What is ridge-push?
gravity pushes the plates further away, causing gravitational sliding
What is slab-pull?
when a plate subducts, the plate sinking into the mantle causes the rest of the plate with it to further slide, causing further subduction
What happens at a conservative plate margin?
- parallel plates move in different directions (oceanic and/or continental)
- pressure builds up
- oceanic = displace water
- continental = fault lines
