Topic 1: Tectonic Processes and Hazards

What is a hotspot volcano?
A hotspot volcano is typically found in the middle of tectonic plates and are thought to be fed by underlying mantle plumes that are unusually hot compared with the surrounding mantle.
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What would be an example of a convergent plate boundary?
An example of a convergent plate boundary is the Himalayas.
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What would be an example of a divergent plate boundary?
An example of a divergent plate boundary is the Mid-Atlantic Ridge.
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What are the two types of crust?
The two types of crust are the THIN oceanic crust and the THICKER continental crust.
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What are the two important factors of an oceanic crust?
The oceanic crust underlies the ocean basins and is composed primarily of basalt.
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What are the two important factors of a continental crust?
The continental crust underlies the continents and is composed primarily of granite.
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What is the lithosphere?
The lithosphere is the surface layer of the Earth with a rigid outer shell composed of the crust and upper mantle. It is on average 100km deep and always moving.
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Where does sea floor spreading occur?
Sea floor spreading occurs at divergent boundaries under the oceans. It is an input of magma forming a mid-ocean ridge for example the Mid-Atlantic Ridge.
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What is the Benioff Zone?
The Benioff Zone is an area of seismicity corresponding with the slab being thrust downwards in a subduction zone, it determines the position and the depth of the hypocentre.
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What is a subduction zone?
A subduction zone is a broad area where two plates are moving together and subduct.
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What is a locked fault?
A locked fault is a fault that is not slipping because of frictional resistance on the fault that is greater than the shear across the fault, that is, it is stuck.
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What is an example of a locked fault?
An example of a locked fault is the Andes.
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How does an earthquake happen?
1 - tectonic strain, elastic energy stored in crustal rocks. 2 - pressure exceeds the strength of the fault, rock fractures. 3 - energy release, seismic waves. 4 - brittle crust rebounds at each side of the fracture, ground shaking = earthquake.
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What is the hypocentre?
The hypocentre is the “focus” point within the ground where the strain energy of the earthquake stored in the rock is first released.
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What are the three types of seismic waves?
The three types of seismic waves are primary waves, secondary waves and love waves.
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What are primary waves?
Primary waves are vibrations caused by compression which spread quickly from the fault at around 8km/sec.
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What are secondary waves?
Secondary waves are waves that more more slowly at around 4km/sec which vibrate at right angles to the direction of travel and CANNOT travel through liquids.
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What are love waves?
Love waves (also known as Q waves) are surface waves with the vibration occurring in the horizontal plain. They have a high amplitude.
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What is one of the most serious second hazards of an earthquake?
One of the most serious second hazards of an earthquake is soil liquefaction.
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What does soil liquefaction do?
Soil liquefaction causes buildings to settle, tilt and then collapse. In some earthquakes tilts of up to 60 degrees have been recorded, for example Japan.
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What is soil liquefaction?
Soil liquefaction is actually the process by which water-saturated material can temporarily lose normal strength and behave like a liquid under pressure of strong shaking.
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What is the epicentre?
The epicentre is the location on the Earth’s surface that is DIRECTLY ABOVE the earthquake focus, i.e the point where an earthquake originates.
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What is another important secondary factor regarding earthquakes?
Another important secondary factor regarding earthquakes is landslides.
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Why are landslides so dangerous?
Landslides are so dangerous because they form on highly susceptible slopes and research from the USGS suggests that over the last 40 years 70% of all deaths caused by earthquakes globally are attributable to (secondary) landslides.
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Landslide statistics to prove how dangerous they are?
Landslide statistics include - 2005, Kashmir and 2008, Sichuan, in both cases landslides caused A THIRD OF ALL DEATHS.
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Card 2

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What would be an example of a convergent plate boundary?

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An example of a convergent plate boundary is the Himalayas.

Card 3

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What would be an example of a divergent plate boundary?

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Card 4

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What are the two types of crust?

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Card 5

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What are the two important factors of an oceanic crust?

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