Volcanoes Flashcards
What are the three layers that make up the Earth
The three layers that make up the earth are the crust, the mantle and the core
What is the crust
The crust is the layer we live on. Its a thin skin of rock around the Earth
How big is the crust
Its 8 - 65 km thick
What’s the difference between the oceanic plate and the continental plate
The oceanic plate is 6-8 km thin, while the continental plate is up to 70km thick
What is the mantle
The mantle is heavy rock that has a size of about half the Earth. The upper mantle is hard, but the lower part of the mantle is hot and soft
What is the core
The core is made up of two parts. The outer core which is liquid and the inner which is solid. Both are made up of iron and some nickel
Where do volcanoes and earthquakes occur?
Earthquakes and volcanoes occur in plate boundaries
What are plate boundaries?
Plate boundaries are the lines were plates meet
Name three possible ways in which plates move
Three ways in which plates move are, pull-apart plates, push-together plates, slide-past plates
What’s another name for “pull-apart” plates
Another name for pull-apart plates is divergent
What’s another name for “push-together” plates
Another name for “push-together” plates is convergent
Why do plates move
Plates move because of convection currents. The high temperature in the core warms the liquid in the mantle, causing it to rise upwards. It eventually meets the crust, which cools it down, causing it to sink downwards. This process is repeated over and over again in a circular manner, making the flow of liquid rock in the convection currents move the tectonic plates slowly
Name 4 types of plate boundaries
Destructive plate boundaries, Constructive plate boundaries, Collision plate boundaries, Conservative plate boundaries
What is a destructive plate boundary
A destructive plate boundary is a convergent boundary where one oceanic plate and one continental plate move together. The oceanic plate moves under the continental plate, as it has a greater density. This process is called subduction
How do destructive plate boundaries cause earthquakes
Destructive boundaries cause earthquakes by the friction of the plates. As the oceanic plate is push under the continental, their plates rub together, creating earthquakes
How do destructive boundaries cause volcanoes
As the oceanic plate is pushed under the continental, it meets with the mantle, causing to melt. Lighter elements of the plate rise as magma, forming volcanoes when it reaches the surface
What is a constructive plate boundary
A constructive plate boundary occurs when two plates move apart. Its a divergent boundary. As the two plates are pulled apart by the convection currents, magma rises between the plates. It turns into basalt that forms a new ocean floor. The ocean floor gets wider by 2cm every year
What is a collision boundary
A collision boundary is when two continental plates move together. Because of the low density of both, neither is pushed downwards. The crust is pushed up and folded to form mountains. The movement of the rock causes earthquakes.
What is a conservative plate boundary
A conservative boundary is when two plates slide past each other. It can create earthquakes, as part of the plates get stuck and then lurch free
What is magma
Magma is molten rock underneath the surface of the earth
What is lava
Lava is molten rock that has broken through the surface of the earth
What are volcanoes
Volcanoes are vents in the ground that allow magma to come out from deep inside the Earth
What are composite volcanoes
Composite volcanoes are volcanoes which are made up from lava and ash
What is a magma chamber
A magma chamber is a store of molten rock deep inside the earth
What is a crater
A crater is a funnel-shaped hole at the top of a volcano from where lava comes out
What are secondary cones
Secondary cones form if the main vent is blocked and magma must come to the surface from another way
What comes out when a volcano erupts
After a volcano erupts, lava, ash and volcanic bombs come out
Name 4 types of volcanoes
Composite volcanoes, lava volcanoes, lava volcanoes and ash volcanoes
What is an ash volcano
Volcanoes formed from ash that are usually steep sided
What is a lava volcano
A volcano with thick, slow-flowing lava that hardens quickly, forming steep-sided volcanoes
What is another type of a lava volcano
A volcano with runny, fast-flowing lava that moves and spreads easily. The volcanoes it forms have gently sloping sides
What are active, dormant and extinct volcanoes
Active volcanoes are volcanoes that have erupted recently and are likely to erupt again
Dormant volcanoes are volcanoes that have erupted in the last 2000 years but not recently
Extinct volcanoes are volcanoes that will most probably never erupt again
What are pyroclastic flows
A pyroclastic flow is a mixture of ash and hot gas erupted from a volcano. These clouds move with a speed of 300km/h and have a temperature of about 300 degrees
What are natural hazards
Natural hazards are dangers to the people and the surroundings that are caused by volcanoes
Give 3 examples of natural hazards
Floods, earthquakes, droughts
Why do people live in volcanic areas
Ash and lava released by volcanoes turns into great soil after a few centuries and good weathering
How does an earthquake occur
When two plates push towards each other, a lot of pressure builds up. When it gets too much, one of the rocks lurches upwards, resulting in the stored energy being released in seismic waves. Seismic waves travel through the earth, shaking everything around them
What is the fault of an earthquake
A crack in the Earth’s crust
What is the focus of an earthquake
The focus is the point where the waves started
What is the epicenter of an earthquake
The epicenter is the point directly above the focus
How are earthquakes measured
Earthquakes are measured by the Richter scale
What are the three P’s
Predict, Protect, Prepare
How can the three P’s reduce the impacts of earthquakes
Predict: Even though it is very difficult to do, we could try to predict when an earthquake will occur. There are a few indications of that, such as the small fore-shocks before the main earthquake or simply the fact that an earthquake hasn’t occurred in a long time
Protect: Buildings should be designed in a way that complies with strict earthquake regulations, to prevent it from falling. This can help save many lives, as many of the people that die from an earthquake is due to the fact that the building they were in collapsed
Prepare: The people should be prepared for what to do when an earthquake occurs. They should be educated, organized and ready for an earthquake to break out at any time
