Unit 1 : Topic 1 : World At Risk Flashcards
Hazard
A perceived natural event that has the potential to threaten both life and property.
Disaster
A hazard becoming reality in an event that causes death and damage to goods/property and the environment.
Geophysical
A hazard formed by tectonic/geological processes (earthquakes, volcanoes, tsunamis).
Hydro-meterological
A hazard formed by hydrological (floods) and atmospheric (storms and droughts) processes.
Risk
The probability of a hazard event occurring and creating loss of lives and livelihoods.
Plate
Rigid, less dense ‘slabs’ of rock floating on the asthenosphere.
Magma
Molten material that rises towards the Earth’s surface when hotspots within the asthenosphere generate convection currents.
Lithosphere
The crust of the Earth, around 80-90km thick.
Asthenosphere
A semi-molten zone of rock underlying the Earth’s crust.
Conservative boundary
A boundary between plates where the movement of the plates is parallel to the plate margin and the plates slide past each other.
Constructive boundary
A boundary between plates where the plates are diverging.
Destructive boundary
A boundary between plates where the plates are converging.
Island arc
A chain of volcanic islands resulting from subjecting lithospheric plates.
Pyroclastic flow
A dense cloud of lava fragments thrown out by an erupting volcano as a result of bursting gas bubbles within the magma.
Lahar
A flow of volcanic debris, either dry or mixed with water as a mudflow.
Subduction
The zone where an oceanic plate descends back into the mantle.
Fault line
A fractured surface in the Earth’s crust where rocks have travelled relative to each other.
Greenhouse effect
The warming of the Earth’s atmosphere due to the trapping of heat that would otherwise be radiated back into space - it enables the survival of life on Earth.
Enhanced greenhouse effect
This occurs when the levels of greenhouse gases in the atmosphere increase, owing to human activity.
Milankovitch cycles
Theory developed by a Serbian scientist, arguing that the surface temperatures of the Earth change over time because of the Earth’s orbit, axis tilt and axis wobble.
