Topic 1 -Hazardous Earth: EQ3 (Tectonic Activity) Flashcards
What is the lithosphere?
the rigid upper part of the earth consisting of the crust and upper mantle
What is the asthenosphere?
the upper layer of the mantle where convection currents move plates
What is the lower mantle?
The inner layer of the mantle where convection currents occur
What is the outer core?
the upper layer of the earth’s core
What is the inner core?
the inner layer of the earth’s core
What are the properties of the oceanic lithosphere?
- solid
- basalt
What are the properties of the continental lithosphere?
- solid
- granite
What are the properties of the asthenosphere?
- dense mobile layer which can flow slowly
- peridotite
What are the properties of the lower mantle?
- solid
- peridotite
What are the properties of the outer core?
- very dense liquid
- iron and nickel
What are the properties of the inner core?
- the densest layer, solid
- iron and nickel
What is a tectonic plate?
A section of the earth’s lithosphere
How do convection currents cause plate movement?
- radioactive decay/residual heat in the mantle and core releases a lot of heat
- when parts of the mantle heat up, become less dense and rise slowly
- as they move upwards they cool down, become more dense and sink
- these circular movements create drag on the base of tectonic plates which causes them to move slowly
What is radioactive decay?
the process where unstable nuclei undergo to become stable
What is residual heat?
heat left over from when the earth was formed
What is a plume and how does it break through the crust?
column of hot, molten material that rises from the Earth’s mantle due to convection currents via volcanoes or hotspots
What happens in a convergent plate boundary (oceanic and continental)? What features are produced?
The more dense oceanic plate is subducted under the less dense continental plate. This can create earthquakes, tsunamis, composite volcanoes and ocean trenches.
Give an example of a convergent oceanic and continental plate boundary
Nazca- oceanic
subducted by
South American continental plate
>creating the Andes mountains in Peru and Chile
What happens in a convergent plate boundary (continental and continental)? What features are produced?
The plates collide and crumple as they are too buoyant, producing fold mountains as the crust is pushed upwards. They can also produce earthquakes due to the stress and pressure from the collision
Give an example of a convergent plate boundary (continental and continental)
The Eurasian and Indian continental plates push into each other
as they are too buoyant
->they crumple and fold, creating the Himalayas in India and Nepal
What happens in a divergent plate boundary? What features are produced?
As the plates move apart, magma from the mantle rises to fill the gap, creating new crust. This can create shield volcanoes and volcanic land if it is underwater. It can also cause earthquakes as tension builds up
Give an example of a divergent plate boundary
The Eurasian and North american oceanic plates pull away from each other
->Creating the Mid-Atlantic Rdige in Iceland
What happens in a conservative plate boundary? What features are produced?
Plates slide past each other or plates slide together at different speeds. They often cause sudden big earthquakes and small daily tremors
Give an example of a conservative plate boundary
The North American and Pacific plates sliding past each other creates tension. As pressure builds up, large cracks are created as the stress is released
->creating the San Andreas Fault in the USA
