2.1: Earthquakes and Volcanoes (Paper 1 and 2) Flashcards
Explain the types of volanoes: (2)
Shield Volcano: A gently sloping volcano produced by very hot, runny lava
Cone/Composite/Strato Volcano: Steeply sloping volcano produced by thick lava
Explain the features of volcanoes: (3)
Crater: Depression at the top of a volcano following a volcanic eruption. It may contain a lake.
Vent: The channel through which volcanic material is ejected
Magma Chamber: The reservoir of magma located deep inside the volcano
Explain the features of earthquakes: (3)
Epicentre: The point on the Earth’s surface directly above the focus of an earthquake. The strength of the shockwaves generally decrease away from the epicentre
Focus: The position within the earth where an earthquake occurs. Earthquakes may be divided into shallow-focus and deep-focus earthquakes depending on how far below the earths surface they occur.
Intensity: The power of an earthquake that is generally measured using the Richter Scale, or sometimes the Mercalli scale.
Explain the distribution of volcanoes (4)
Uneven: The distribution of earthquakes is very uneven (1)
Plate Boundaries: They are mostly along plate boundaries (1)
Crustal Instability: Which are regions of crustal instability and techtonic activity. (1)
Hotspots: Some occur in the middle of a plate known as hotspots (1)
Explain the distribution of earthquakes: (3)
Most of the earths earthquakes occur in linear chains along all types of plate boundary (1)
- Some earthquakes occur in the middle of a plate due to movement (1)
- Some may occur as a result of human activity like mining and building large dams (1)
Explain the plate movement and boundaries and the effects (4)
Constructive/Divergent: Two plates move apart from each other and exposes the magma, as a result of this the volcano erupts. Destructive plate boundaries can cause both earthquakes and volcanoes (1)
Convergent (Destructive) : One oceanic and one continental plate move towards each other. The oceanic plate subducts because of its greater density. Friction between the continental and oceanic plates causes heat which melts the rock into magma which is built-up. The magma then rises and cracks through the surface and eventually erupts explosively. Destructive boundaries can cause both earthquakes and volcanoes. (1)
Convergent (Collision): Two plates of the same density move towards eachother. They then collide and because they have the same density the land is pushed upwards and forms fold mountains. Volcanoes can form here but its mostly earthquakes (1)
Transform/Conservative: Two plates move past each other in opposite directions or in the same direction in different speeds. The plates will eventually lock and cause an earthquake to occur. (1)
Explain the causes of an earthquake: (3)
- Build up of pressure as a result of plate movement (1)
- Earthquakes are weaker at constructive plate boundary because they move apart (1)
- At the rest, they are all stronger because plates are moving towards each other (1)
Explain the causes of a volcano: (4)
- Build up of pressure as a result of plate movement (1)
- Hotspots where the magma burns through the thin layer of crust (1)
- At destructive boundaries, since a composite volcano is formed, they are explosive
- At constructive boundaries, since a shield volcano is formed, the volcano is less explosive. (1)
Explain the effects of earthquakes on people and the environment:
People (4)
Environment (3)
PEOPLE:
- Loss of infanstructure (1)
- Disruption to water and sewage systems (1)
- Loss of electricity and gas (1)
- Spreading of water-borne diseases (1)
ENVIRONMENT:
- Floods may damage the environment (1)
- Release of hazardous material (1)
- Spreading of water-borne diseases (1)
Explain the effects of volcanoes on people and the environment
People (5)
Environment (3)
PEOPLE:
- Destruction of infrastructure (1)
- Loss of life (1)
- Loss of Farmland (1)
- Destruction of transport (1)
- Disruption of communication (1)
ENVIRONMENT:
- Loss of life (1)
- Loss of forests (1)
- Acid rain from volcanic ash contains toxic chemicals (1)
Explain the hazards volcanoes bring to people:
Direct (4)
Indirect (4)
DIRECT:
- Pyroclastic flows
- Lava flows
- Volcanic gases
- Volcanic Bombs
INDIRECT:
- Ash fallout
- Landslides
- Tsunamis
- Acid rainfall
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Explain the opportunities volcanoes bring to people (4)
- Geothermal Power
- Fertile soils
- Soils rich in minerals
- Attracts tourism
Explain how we can reduce the impacts of earthquakes: (4)
- Better forecasting and warning (monitoring plate movements)
- Building location
- Building design (steel-framed buildings and deep foundations)
- Emergency procedures
Define the following terms:
- Ash (1)
- Cinders (1)
- Magma (2)
- Lava (2)
- Ash: Very fine-grained volcanic material
- Cinders: Small-sized rocks and coarse volcanic materials
- Magma: Molten rock within the earth. However its called lava when it reaches the surface
- Lava: Molten magma that has reached the earth’s surface. It may be liquid or may have solidified
Define the term Pyroclastic flow (1)
Superhot flows of ash, pumice and steam at speeds of over 500km/h
