Tectonics Flashcards
Where do most earthquakes occur?
At plate boundaries or intraplate regions, due to stress build-up
Where are most volcanoes found?
Convergent and Divergent
Hotspots
What percentage of volcanoes occur at the Ring of Fire?
75%
What are intraplate volcanoes?
Volcanic activity found in the middle of oceanic and continental plates
What happens at oceanic intraplate volcanoes?
Magma melts through surface of outer core
What happens at continental intraplate volcanoes?
The plate is stretched, creating weakness for magma to break through
What are mantle plumes?
Isolated plumes of heat that cause hotspots
Where do plates move at divergent boundaries?
Away
What type of eruptions do divergent plates tend to have?
Effusive, with basaltic magma
Where do plates move at conservative boundaries?
Past each other
Where do plates move at convergent boundaries?
Towards each other
What is the inner core?
Solid centre of Earth
What is the outer core?
Liquid layer creates magnetic field
What is the mantle?
Solid layer between core and lithosphere
/What is the asthensophere
Semi-molten layer that causes convection currents
What is the lithosphere?
Brittle upper mantle and crust
What is Wegner’s theory?
Continental drift (1912)
What is the one land mass called?
Pangea
What is mantle convection?
Heat from core circulates in mantle
What is Palaeomagnetism and seafloor spreading?
Resulting from minerals cooling aligned with the magnetic polarity of Earth
What is subduction?
Crust pulls apart further from oceanic ridge, subducted crust cools, becomes increasingly heavy
What is slab pull?
The denser plate sinks back into the mantle under the influence of gravity. It pulls the rest of the plate along behind it.
What is seafloor spreading?
Hot magma pushes through, and cools forming new oceanic crust
What is ridge pull?
The denser plate sinks back into the mantle under the influence of gravity. It pulls the rest of the plate along behind it.
What is the Benioff Zone?
Zone of seismicity
What is focal depth?
Depth from the earth’s surface to the earthquake’s energy orgin
