Plate Tectonics 🍽🌏 Flashcards
Name the four LAYERS of the Earth:
> Crust
Mantle
Outer Core
Inner Core
What are the 2 types of CRUST and what are they like?
The two types of crust are:
> Oceanic
> Continental
The Earth’s crust is quite thin, as little as 3 miles under the oceans, but it is much thicker under the continents, about 25 miles. So, we talk about Oceanic and Continental
Explain CONVECTION CURRENTS and how this effects the movement if the plates:
The plates float on the mantle and are made to move by convection currents
Convection currents rise up from particular hotspots near the core. As the molten magma of the mantle moves, so the plates are carried with it
Give a brief description of the CRUST:
It ‘floats’ on the surface, at the top
Give a brief description of the MANTLE:
A hot layer of semi-solid rock below the crust
Give a brief DESCRIPTION of the core(s) of the Earth:
At the centre of the Earth is the core. This is made up of two distinct parts; a thick liquid OUTER layer and a solid INNER CORE
Give a description of a DESTRUCTIVE plate boundary:
> The crusts involved are: OCEANIC and CONTINENTAL
When they meet, the Oceanic gets pushed down as it’s
HEAVIER
The point where this happens is called the SUBDUCTION zone
This leads to the formation of an OCEAN TRENCH
The FRICTION caused when it sinks can create huge earthquakes
The crust re-melts and gets forced upwards, due to pressure, to
form a volcano
Give a description of a CONSTRUCTIVE plate boundary:
> Plates which move away from each other are known as
DIVERGING plates
Magma forces its way to the surface to fill the gap created
These creates, or constructs new land once cooled
This may result in the development of underwater volcanoes and
ridges of land
The most famous example is ‘the Mid-Atlantic Ridge’
Give a description of a CONSERVATIVE plate boundary:
> This is when plates slide past each other
No crust is MADE or DESTROYED
When plates get stuck, friction builds up and eventually ‘jump’ free
unable to cope with the stress
This causes an EARTHQUAKE
Give a description of COLLISION plate boundary:
> Both plates are the SAME type of crust
They are both EQUAL in weight, meaning neither can sink
The plates crash together and start to be FORCED upwards
This creates FOLD mountains
What is the definition of a VOLCANO?
A volcano is an opening, or rupture, in a planet’s surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface
What are the 3 different types of VOLCANO?
> Active
Dormant
Extinct
What is an ACTIVE volcano?
One which is liable to erupt at any time
eg. Mount Etna
What is a DORMANT volcano?
One which has not erupted for many years
eg. Mount Pinatubo
What is an EXTINCT volcano?
One which has not erupted in a VERY long time and is unlikely to erupt again
eg. Mount Kulal
Name 3 BENEFITS of living near a volcano:
> Energy can be sourced from Geothermal energy
Rocks provide building materials and resources
Water boiled underground produces a gas which can generate
electricity
Name 2 PROBLEMS with living near a volcano:
> It can be very dangerous
Volcanic landslides can destroy buildings
Lava pollutes rivers and then burns down trees and houses in
its path
What is a TSUNAMI?
A TSUNAMI is a series of ocean waves that send surges of water, sometimes reaching height of over 100 feet, onto land. The ‘walls of water’ can cause widespread destruction when they crash ashore
What causes TSUNAMIS?
They are caused typically by undersea earthquakes at tectonic plate boundaries. When the ocean floor at a plate boundary rises or falls suddenly, it displaces the water above it and launches the rolling waves that will become the TSUNAMI
How fast do TSUNAMIS travel?
TSUNAMIS race across the sea at up to 500 miles per hour; about as fast as a jet aeroplane. At that pace they can cross the entire expanse of the Pacific Ocean in less than a day
How can we ‘prevent’ TSUNAMIS?
The best defence against any TSUNAMI is early warning that allows people to seek HIGHER ground. Seismic equipment can be used to identify TSUNAMIS at sea, then the Warnung can be given
What is an EARTHQUAKE?
> An EARTHQUAKE is caused by a sudden movement between
the plates
The ground shakes suddenly, due to a piece of the Earth’s crust
having moved
This produces very strong shockwaves that travel out from the
centre of the crust
What is the ‘FOCUS’ of an earthquake?
The FOCUS is the point where the earthquake STARTS. The waves spread out from the FOCUS. Near the FOCUS, the waves are stronger and more damage occurs
What is the ‘EPICENTRE’?
The EPICENTRE is the point on the Earth’s surface immediately ABOVE the FOCUS
How do we MEASURE an earthquake?
> The SEISMOGRAPH measures the shockwaves, or seismic
waves
The RICHTER SCALE measures the strength of the earthquake,
or the energy released
The MERCALLI SCALE measures the intensity
What are the 2 SHORT TERM effects of an earthquake?
> Landslides may occur and Tsunamis may cause flooding in
coastal areas
> People may be killed or injured, homes destroyed, communication
links disrupted, water pipes burst and water supplies may be
contaminated
What are the 2 LONG TERM effects of earthquakes?
> Shops and businesses may be destroyed. The damage to
transport and communication links can make trade difficult
and businesses may take a long time to recover from this
> The cost of rebuilding a settlement is high and could take years.
Investment in the area may only be focused on repairing the
damage of the earthquake. Income could be lost
