Tectonic Processes and Hazards Flashcards
Asthenosphere
The part of the mantle, below the lithosphere, where the rock is semi-molten.
Benioff zone
The area where friction is created between colliding tectonic plates, resulting in intermediate and deep earthquakes.
Collision plate boundary
Where two plates move towards each other causing a very slow collision which is likely to cause folding and faulting of crustal rocks and the uplift of continental crust to form fold mountains.
Community adaptation
People within communities, either whole or parts of settlements, work together to change their way of life so that the impact of a tectonic hazard event is not as hazardous.
Community preparedness
People within communities, either whole or parts of settlements, work together to change their way of life so that the impact of a tectonic hazard event is not as hazardous.
Conservative plate movement
Where two plates meet and move alongside each other in a similar direction or opposite direction, usually at different speeds. Friction between the two plates is great and stresses and strains build up to create shall earthquake foci.
Also transform plate boundary.
Constructive plate boundary
Where two plates move in opposite directions, leaving a zone of faulting and a gap into which magma from the asthenosphere rises.
Also divergent plate boundary.
Constructive plate boundary
Where two plates move in opposite directions, leaving a zone of faulting and a gap into which magma from the asthenosphere rises.
Also divergent plate boundary.
Convection currents
Hot, liquid magma currents moving in the asthenosphere.
Convergent plate boundary
Where two plates move towards each other and at the boundary the denser oceanic plate (basaltic) is subducted beneath the less dense continental plate (granitic), creating surface features such as a trench, and deep features such as the Benioff zone.
Also destructive plate boundary.
Crustal fracturing
When energy released during an earthquake causes the Earth’s crust to crack.
Disaster
The realisation of a hazard when 10 or more people are killed or 100 or more are affected
Epicentre
The point on the Earth’s surface directly above the focus of an earthquake.
Focal depth
The depth at which an earthquake starts (focus). It is divided into shallow, intermediate and deep. Shallow earthquakes have the greatest impacts, as the seismic waves have not lost as much of their energy by the time they reach the surface.
Focus
The point inside the Earth’s crust from which the pressure is released when an earthquake occurs.
Also hypocentre.
Geological structure
The arrangement of rock in layers, or folds and the joints and bedding planes within them.
Governance
The many ways that institutions and individuals manage their common affairs
Hazard
A perceived natural event that has the potential to threaten life and property
Hazard-management cycle
A theoretical model of hazard management as a continuous four-stage cycle involving mitigation, preparation, response and recovery.
Hazard profile
A technique used to understand and compare the physical characteristics of different types of hazard e.g. duration
Hot spot
Points within the middle of a tectonic plate where plumes of hot magma rise and erupt.
Hydrometeorological hazards
Natural hazards caused by climate processes (including droughts, floods, hurricanes and storms).
Intra-plate earthquakes
Earthquakes which occur in the middle or interior of tectonic plates, rather than on plate margins.
Jokulhlaups
Glacial outburst floods caused by volcanic activity melting ice