TECTONICS Flashcards
(21 cards)
Lithosphere
The surface layer of the earth is a rigid outer shell composed of the crust and upper mantle.
Seismic hazards
Generated when rocks under surface come under such stress they break and become displaced.
Intra-plate earthquakes
These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes.
Oceanic crust
Thin, composed of primarily basalt.
Continental crust
Thicker, composed primarily of granite.
Paleomagnetism
Results from the zone of magma ‘locking in’ or striking the earths magnetic polarity when it cools. Can be used to determine historic periods of large scale tectonic activity.
Locked fault
A fault that is not slipping because of frictional resistance on the fault is greater than the stress across the fault, it is stuck.
The Benioff zone
An area of seismicity corresponding with the slab being thrust downwards in subduction zone.
Hypocentre
The focus point within the ground where the strain energy of the earthquake stored in the rock is first released.
Locked fault
A fault that is not slipping because the frictional resistance on the fault is greater than the shear stress across the fault, that is, it is stuck.
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.
Intensity
A measure of the ground shaking.
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.
Epicentre
The location on the earth’s surface that is directly above the earthquake focus.
Focus
The point where an earthquake originates.
Fault
A fracture in the rocks that make up the earth’s crust.
Seismic waves
Waves that transmit the energy released by an earthquake.
Tectonic hazard profile
A technique used to try to understand the physical characteristics of different types of hazards. Also can be used to analyse and assess the same hazards at contrasting locations or at different times.
Tectonic hazard profile criteria
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Magnitude Speed of onset Duration Areal extent Spatial predictability Frequency
Governance
The sum of the many ways individuals and institutions, public and private, manage their common affairs.
Disaster hotspot
A country or area that is extremely disaster prone for a number of reasons.
