Key Terms Flashcards - Tectonic Hazards

Key terms for Tectonic Hazards and Processes. Definitions of key terms taken from a Hodder Education book on A-Level Geography. Please leave positive feedback or constructive criticism.

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Seismic Hazards
Generated when rocks within 700km of the Earth's surface come under such stress that they break and become displaced.
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Volcanic Hazards
Associated with eruption events.
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Intra-Plate Earthquakes
These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes.
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Volcano
A landform that develops around a weakness in this Earth's crust from which molten magma, volcanic rock, and gases are ejected or extruded.
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Plate tectonics
A theory developed more than 60 years ago to explain the large-scale movement of the lithosphere (the outermost layer of the Earth). It was based around the evidence from sea floor spreading and ocean topography, marine magnetic anomalies, etc.
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Lithosphere
The surface layer of the Earth is a rigid outer shell composed of the crust and upper mantle. It is on average 100km deep. The lithosphere is always moving, but very slowly, fuelled by rising heat from the mantle which creates convection currents.
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Paleomagnetism
Paleomagnetism results from the zone of magma "locking in" or "striking" the Earth's magnetic polarity when it cools. Scientists can use this tool to determine historic periods of large-scale tectonic activity.
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Subduction zones
Broad areas where two plates are moving together, often with the thinner, more dense oceanic plate descending beneath a continental plate. The contact between the plate is sometimes called a thrust or megathrust fault.
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Locked fault
A fault that is not slipping because the frictional resistence on the fault is greater than the shear stress across the fault; it is stuck. Such faults may store strain for extended periods that is eventually released in a large magnitude earrhqauke.
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Hypocentre
The "focus" point within the ground where the strain energy of the earthquake stored in the rock is released. The distance between this and the epicentre on the surface is called focal length.
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Soil liquefaction
The process by which water-saturated material can temporarily lose normal strength and behave like a liquid under the pressure of strong shaking. Liquefaction occurs in saturated soils and can make soil particles move easily.
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Intensity
A measure of the ground shaking. It is the ground shaking that causes building damage and collapse, and the loss of life from the hazard.
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Magnitude
The magnitude of an earthquake is related to the amount of movement, or displacement, in the fault, which is in turn a measure of energy release.
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Epicentre
The location on the Earth's surface that is directly above the earthwuakes focus, i.e. the point where an earthquake originates.
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Tsunami
The word comes from two Japanese words: tsu (port or harbour) and nami (wave or sea). Tsunamis are initiated by undersea earthquakes, landslades, slumps and sometimes volcanic eruptions. Charactarised by long wavelengths, low amplitude, fast velocity
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Hazard
A perceived natural/geophysical event that has the potential to threaten both life and property. Involves people near or at its location. Earthquakes would not be hazards if people did not live in buildings that collapse as a result of ground shaking
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Disaster
The realisation of a hazard when it causes a significant impact on a vulnerable population. CRED states that a hazard becomes a disaster when: 10+ people are killed or 100+ people are affected.
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Risk
The exposure of people to a hazardous event. More specifically, it is the probability of a hazard occuring that leads to the loss of lives and/or livelihood.
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Resilience
In the context of hazards and disasters, resilience can be thought of as the ability of a system, community or society exposed to hazards to resist, absorb and recover from the effects of a hazard.
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Development
Development is linked to an improving society enabling people to achieve their aspirations. It includes the provision of social services, acquisition of economic assets, improved productivity and reducing vulnerability to natural disasters.
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Tectonic hazard process
A technique used to try to understand the physical characteristics of different types of hazards. Hazard profiles can be used to analyse and assess the same hazards which take place in contrasting locations or at different times.
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Inequality
Usually refers to an unfair situation or distribution of assets and resources. May also be used when people, mations and non-state players have different levels of authority, competence and outcomes.
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Governance
The sum of the many ways individuals and institutions manage their common affairs. A continuing process through which conflicting or diverse interests may be accomodated and co-operative action may be taken.
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Disaster hotspot
A country or area that is extrememly disaster prone for a number of reasons.
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Other cards in this set

Card 2

Front

Associated with eruption events.

Back

Volcanic Hazards

Card 3

Front

These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes.

Back

Preview of the back of card 3

Card 4

Front

A landform that develops around a weakness in this Earth's crust from which molten magma, volcanic rock, and gases are ejected or extruded.

Back

Preview of the back of card 4

Card 5

Front

A theory developed more than 60 years ago to explain the large-scale movement of the lithosphere (the outermost layer of the Earth). It was based around the evidence from sea floor spreading and ocean topography, marine magnetic anomalies, etc.

Back

Preview of the back of card 5
View more cards

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