Y9 Geog HWK 1.9 Keywords

composite volcanoes

steep-sided volcanoes found at constructive plate margins

collision plate boundary

where two continental plates collide and push the land upwards creating mountains but not volcanoes

conservative plate boundary

two plates sliding alongside each other, in the same or different directions

constructive plate boundary

tectonic plate margin where rising magma adds new material to plates that are diverging or moving apart

continental crust

the low density, thick outer layer of Earth which forms our continents

convection currents

circular movement of heat within Earth which drive the movement of tectonic plates

destructive plate boundary

tectonic plate margin where two plates are converging and oceanic plate is subducted – there could be violent earthquakes and explosive volcanoes

earthquake

a sudden or violent movement within the Earth’s crust

fold mountains

uplifted land that is crumpled by the collision of two plates

hot spots

Where mantle plumes occur under the Earth’s crust causing it to melt and thin so magma is able to break through the surface, forming volcanoes

lava

magma that has erupted from a volcano on the earth’s surface

magma

molten rock beneath the Earth’s surface

mantle

a hot, dense layer of Earth found between the crust and core

oceanic crust

the dense, thin outer layer of Earth that mostly lies underneath the ocean

plate margin / boundary

the border between two tectonic plates

primary effects

initial impact of a natural event on people and property, caused directly by it, i.e. the buildings collapsing following an earthquake

secondary effects

after-effects that occur as indirect impacts of a natural event, sometimes on a longer timescale, i.e. fires due to ruptured gas mains, resulting from the ground shaking

seismicity

the frequency and distribution of earthquakes in a certain area, recorded by seismographs

shield volcano

broad, flat volcano with non-violent eruptions formed at constructive margins and at ‘hot spots’

subduction

at a destructive margin, where the denser oceanic plate moves beneath the less dense continental plate

tectonic hazard

natural hazard caused by the movement of tectonic plates (i.e. volcanoes and earthquakes)

tectonic plate

section of the Earth’s crust about 100km thick

tsunami

huge waves caused by earthquakes uplifting the sea bed

volcano

an opening in the Earth’s crust from which lava, ash and gases erupt