Key terms- topic 1 Flashcards
Accretion Wedge
The accumulation of material at the point of subduction.
Asthenosphere
The upper mantle layer of the Earth. It is semi-molten and approximately 2000km wide.
Volcanic Island Arc
A series of volcanoes (often in the shape of an arc) that are formed consecutively, as a tectonic plate moves across a magma plume.
Benioff zone
A region of the subducting plate, most affected by pressure and friction, where most destructive margin earthquakes originate.
Volcanic Explosivity Index (VEI)
A measure of the magnitude of a volcano’s eruptions.
Viscosity
An internal property of a fluid that offers resistance to flow ie low viscosity= runny
Subduction
Oceanic plate is forced below continental plate, due to the oceanic plate being more dense than the continental plate.
Seismic waves
The energy released during an earthquake, in the form of Primary, Secondary, Love and Rayleigh Wave
Secondary waves
An earthquake wave causing vertical displacement within the body of rock.
Richter scale
A logarithmic measure of earthquake’s intensity.
Rayleigh waves
A surface earthquake wave causing both horizontal and vertical displacement
Pyroclastic flows
A mixture of gases and rock fragments, at high temperatures travelling at rapid
speeds.
Primary waves
An earthquake wave causing compressions within the body of rock
Parks model
A model describing the decline and recovery of a country over time, following a natural disaster.
Paleomagnetism
The alternating polarisation of new land created. As magma cools, the magnetic elements within will align with the Earth’s magnetic field, which can alternate over thousands of years
Oceanic crust
Crust, usually thinner than continental crust, that forms the sea floor. It is on average 7km thick.
Moment magnitude scale
A measure of an earthquake’s energy released, considered the most accurate measure.
Mid oceanic ridge
Parting oceanic plates at a constructive plate boundary creates a ridge, with new land at the base of the oceanic valley.
Love waves
A surface earthquake wave with horizontal displacement.
Lithosphere
The upper crust of the Earth (average thickness = 100km)
Lahars
- A flow of mud and debris