Studied by 4 people
continental crust
crust found underneath large land masses
oceanic crust
crust found underneath the oceans. (ocean floor)
epicentre
the Earth's surface directly above the focus
focus
where the earthquake starts below the Earth's surface
how deep under the crust are shallow-focus EQs?
0-70km
how deep under the crust are intermediate EQs?
70-300km
how deep under the crust are deep-focus EQs?
greater than 300km
Describe what a hot spot is. [2]
an area of the earth’s crust where unusually high heat flow is linked to volcanic activity
constructive plates
tectonic plates moving apart
both volcanic eruptions and earthquakes can occur here (Mid-Atlantic Ridge)
destructive plates
tectonic plates move towards one another.
The oceanic crust is forced to sink, the continental crust rises above
Conservative plates
tectonic plates move past each other
only earthquakes occur here
Collison plates
two plates move towards each other
the crust is forced upwards forming fold mountains such as the Himalayas
Convection currents
Hot currents that make plates move
what are earthquakes caused by?
EQs occur at all plate boundaries
EQs happen when tectonic plates move, causing pressure and a sudden violent shake occurs
they can also occur when humans drill or mine into the crust
Seismic waves
Shock waves from earthquakes
what does a Richter scale measure?
the magnitude of earthquakes
what are seismometers used to detect?
seismic waves from earthquakes
what does the Mercalli scale measure?
the damage caused by earthquakes (1-10)
Explain how the movement of tectonic plates at a destructive plate boundary causes volcanoes to form. [4]
The tectonic plates move towards each other and one plate is forced to subduct
this causes crust to melt due to friction
pressure in magma chamber builds up
molten material rises as it is dense
magma moves through cracks of the crust
Volcanoes are formed on the margins ___________ and __________
Constructive and destructice
State 3 features about composite volcanoes
found at destructive margins
most violent eruptions
lava is thick and heavy
state 3 features about shield volcanoes
found at constructive margins
Not as violent eruptions
Lava is thin and runny
Name the process that causes the Earth’s tectonic plates to move. [1]
convection currents
