Our Restless Planet Flashcards
Describe the structure of the Earth.
Inner Core
Outer Core
Mantle
Crust
Name most of the tectonic plates.
PAANSIE
Pacific Plate
African Plate
Antarctic Plate,
North American Plate,
South American Plate
Indo-Australian Plate,
Eurasian Plate
Name the 4 plate boundaries where tectonic plates meet.
Constructive (divergent)
collision
conservative
destructive
These are just different ways that two tectonic plates could interact.
Explain the location of volcanoes.
60% of all active volcanoes occur at the boundaries between tectonic plates.
Most volcanoes are found along a belt, called the “Ring of Fire” that encircles the Pacific Ocean.
Describe what comes out of a volcano.
Lava.
Describe the impact of a volcanic eruption on people in Merapi.
353 people were killed
577 people were injured
Overcrowded evacuation centres led to poor sanitation, no privacy and a serious risk of disease.
People, particularly farmers, lost their homes and livelihoods.
350,000 people were made homeless.
Describe the impact of a volcanic eruption on people in Montserrat.
Destroyed between 100 -150 houses.
Farmland - Some farmers regularly returned to the Exclusion Zone to care for animals or tend to crops. After the eruption much of this land was destroyed by volcanic deposits.
19 people were killed by the pyroclastic flows and surges. Common injuries to the seven people injured were severe burns to the feet as a result of walking on ash deposits only about 1-2 cm deep.. Other survivors suffered burns to various parts of their bodies, including inhalation injuries and burns to the nostrils and mouth.
Transport - Debris from the pyroclastic flow came within 50 metres of W.H. Bramble Airport. The airport was undamaged but since then the airport has not re-opened. Although the capital, Plymouth, was no longer occupied the port was still in use. On the day of the eruption a fuel tanker was connected to the port to deliver fuel for vehicles. The tanker was notified and fuel lines to the port were disconnected. Although the port was not destroyed by this eruption, an emergency jetty was built in the north of Montserrat. Many of the islanders relied on cars and vans to get themselves about the island.
Describe the benefits that volcanoes can bring and why someone might want to live in a volcanic region.
Volcanic rock and ash provide fertile land which results in a higher crop yield for farmers.
Tourists are attracted to the volcano, which increases money to the local economy.
Geothermal energy can be harnessed, which provides free electricity for locals.
Minerals are contained in lava, eg diamonds - these can be mined to make money
What is the difference between magma and lava?
Magma for molten rock that is underground and lava for molten rock that breaks through the Earth’s surface.
Describe where earthquakes occur?
Over 90% of earthquakes – including almost all of the largest and most destructive ones – happen at or near so-called plate boundaries.
What affects temperature variations in the Earth’s centre?
The fluctuating temperatures in the core depend on pressure, Earth’s rotation, and the varying composition of core elements.
Describe a collision plate boundary.
If two continental plates collide, neither can sink and so the land buckles upwards to form fold mountains.
Describe a constructive plate boundary.
At constructive plate boundaries, the tectonic plates are moving away from one another. The Earth’s crust is pulled apart to create a new pathway for rising hot magma to flow on to the surface. Volcanoes can sometimes form in these setting; one example is Iceland.
Describe how a composite volcano is formed and some of its characteristics.
Composite volcanoes are found on
convergent plate boundaries, where the oceanic crust
subducts beneath the continental crust.
Composite volcanoes have the following characteristics:
Andesitic magma, which is lower in temperature, has more silica and a lot of dissolved gases and is more likely to explode when it reaches the surface.
Acidic lava, which is very viscous (sticky).
Steep sides as the lava doesn’t flow very far before it solidifies.
Alternate layers of ash and lava. For this reason, they’re also known as
stratovolcanoes. Strato means layers.
Violent eruptions.
Longer periods between eruptions.
Mount Fuji in Japan and Mount Shasta in California are examples of composite volcanoes.
What is Pyroclastic flow?
A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases. It occurs as part of certain volcanic eruptions.
Describe how a shield volcano is formed and some of its characteristics?
Shield volcanoes are found on
divergent plate boundaries, where two plates move away from one another.
Shield volcanoes have the following characteristics:
basaltic magma, which is high in temperature, very low on silica and with low gas content - this type of magma produces fluid lava with very little explosive activity
basic lava, which is non-acidic and very runny
gentle sides as the lava flows for long distances before it solidifies
no layers, as the volcano just consists of lava
less violent eruptions
shorter periods between eruptions
Describe a conservative plate boundary.
A Conservative plate boundary is where two crustal plates slide past each other, and the movement of the plates is parallel to the plate margin. The plates move with relative horizontal movement which is either sinistral (left) or dextral (right).
Describe a destructive plate boundary.
A destructive plate boundary is a convergent plate boundary where two plates (oceanic plate and the continental plate) meet, and the more dense oceanic plate is forced under the continental plate. The subduction zone is point at which the plates meet and the friction created heats up the plates forming a magma chamber.
How do we monitor volcanic activity?
Tiltmeter
Describe the structure of a volcano.
magma chamber
- this is where the molten rock is stored beneath the ground
main vent
- this is the channel through which
magma
travels to reach the Earth’s surface
secondary vent
- some magma may escape through the side of the volcano, particularly if the main vent becomes blocked
crater
- this is found at the top of the volcano, where the magma erupts from
Name some of the negative effects of a volcano?
Volcanoes are dangerous. They can kill people and damage property.
Economic activity can suffer as it is hard for businesses to operate after an eruption.
Habitats and landscapes are damaged by lava flows.
What is a tilt meter?
A device that measures any changes in the ‘tilt’ of the landscape. It is used often for studying volcanoes.
Describe the composition/state/temp of the different layers of the Earth.
Inner Core - solid - 6000 - iron and nickel
Outer Core - liquid - 5000 - iron and nickel
Mantle - liquid - 3000 - magma
Crust - solid - 22 - oceanic (younger/denser) and continental (older/thicker) crusts.
Describe ash.
Fine rock particles.
Can travel a long distance.
Near to a volcano, it can be thick (like fog) but the further it travels, the thinner the layers.
It can cover a large surface area.
It can cuase lung damage or lung disease.
Can obstruct people’s vision.
Can block sunlight.
Can interfere with a plane’s engines.
Desribe volcanic bombs.
They do not travel a lenghty distance.
Can be various sizes.
Can injure or kill you.
Start fires.
Damange plants.
Describe the damage lava can cause.
Covers large areas.
Covers the ground in rock.
Pushes down houses.
Starts fires.
Describe the damage lahars can cause.
Volcanic mudflow. They are fast-moving mixutures of water, ash, hot rocks and debris.
Heavy rainfall can wash the volcanic rock down from the volcano sides.
Can be very destructive to anything in its path.
Can flow much faster than someone can run.
Can occur at any time, even months or years after the eruption.
Describe volcanic gases.
Range of types of gases such as water vapour, sufur dioxide, hydrogen chloride, carbon dioxide and flourine.
List some primary effects of an earthquake.
Building collapsing.
Falling objects.
Land being destroyed.
Properties being destroyed.
List some secondary effects of an earthquake.
Fire.
Tsunami.
Disease.
Some communications may be weakened.
Impact on tourism and the economy.
How are earthquakes measured?
Richter scale - total amount of energy released from the earthquake.
Mercalli scale - total amount of damage caused by an earthquake and it a scale of 1-12.
What precious materials can be found in volcanic areas?
Gold
Aluminium
Diamonds
Nickel
Lead
Zinc
Copper
What is a volcanologist?
Someone who studies and monitors the Earth’s volcanoes in all stages of activity, all over the planet.
