Tectonic plates
The earth's surface is made up of two types of crust:
- Oceanic crust - found underneath the oceans. It is denser than continental
crust and can be subducted.
- Continental crust - found under land masses or continents. It is generally older
than oceanic crust and is less often destroyed.
Earthquakes are found along all types of plate margins, Volcanoes however, only
occur at constructive and destructive plate margins.
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3 types of plate boundaries
- destructive
As the plates collide, the oceanic plate is forced beneath the continental plate. This is known
as subduction. This happens because the oceanic plate is denser (heavier) than the
continental plate.
- constructive
At a constructive plate margin the plates move apart from one another. When this happens
the magma from the mantle rises up to make (or construct) new land in the form of a shield
volcano. The movement of the plates over the mantle can cause earthquakes.
- Transform (Conservative)
At a conservative plate margin, the plates move past each other or are side by side moving
at different speeds. As the plates move, friction occurs and plates become stuck. Pressure
builds up because the plates are still trying to move. When the pressure is released, it sends
out huge amounts of energy, causing an earthquake. The earthquakes at a conservative
plate boundary can be very destructive as they occur close to the Earth's surface. There are
no volcanoes at a conservative plate margin.
—————————————————————————————————
Types of waves
Primary - arrives first,fast moves through solid rock and fluids, pushes and pulls in the
direction of travel
The earth's surface is made up of two types of crust:
- Oceanic crust - found underneath the oceans. It is denser than continental
crust and can be subducted.
- Continental crust - found under land masses or continents. It is generally older
than oceanic crust and is less often destroyed.
Earthquakes are found along all types of plate margins, Volcanoes however, only
occur at constructive and destructive plate margins.
————————————————————————————————
3 types of plate boundaries
- destructive
As the plates collide, the oceanic plate is forced beneath the continental plate. This is known
as subduction. This happens because the oceanic plate is denser (heavier) than the
continental plate.
- constructive
At a constructive plate margin the plates move apart from one another. When this happens
the magma from the mantle rises up to make (or construct) new land in the form of a shield
volcano. The movement of the plates over the mantle can cause earthquakes.
- Transform (Conservative)
At a conservative plate margin, the plates move past each other or are side by side moving
at different speeds. As the plates move, friction occurs and plates become stuck. Pressure
builds up because the plates are still trying to move. When the pressure is released, it sends
out huge amounts of energy, causing an earthquake. The earthquakes at a conservative
plate boundary can be very destructive as they occur close to the Earth's surface. There are
no volcanoes at a conservative plate margin.
—————————————————————————————————
Types of waves
Primary - arrives first,fast moves through solid rock and fluids, pushes and pulls in the
direction of travel
