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 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
