Chapter 6: Managing Natural Hazards

supervolcano

a volcano that erupts at least 1000km³ of material

natural hazard

a naturally occurring event that will have a negative impact on people

risk

the probability of a natural hazard occurring and the losses or damage that might result from that natural hazard

natural disaster

when a natural hazard causes damage and people cannot cope

geological hazards

earthquakes and volcanic eruptions

climatic hazards

droughts, tropical cyclones, floods

vulnerability

the characteristics and circumstances of people in a community that make them susceptible to the impacts of a natural hazard

plate tectonics

a theory that explains the formation of the important features of the earth’s surface and how the continents move

fold mountains

mountains created when two or more tectonic plates are pushed together, compressing rocks and fold theming upwards

parts of the earth

inner core, outer core, mantle, crust

inner core/ outer core

made of iron and nickel

sima

oceanic crust, rich in silicate and magnesium minerals (basalt)

sial

continental crust, rich in silicate and aluminium minerals (granite)

basalt

igneous rock formed at constructive plate boundaries

granite

igneous rock formed at destructive plate margins

asthenosphere

layer of the earth below the lithosphere

tectonic plate

a piece of the lithosphere that moves slowly on the asthenosphere

lithosphere

the outer and rigid layer of the earth that contains the crust and the upper part of the mantle

plate boundary

where two or more plates meet

constructive(divergent) plate boundary

two oceanic plates pulling away from each other, allowing magma to rise to the surface due to convection currents, forming new basaltic ocean crust

sea-floor spreading / ridge push

process by which oceans are formed at constructive plate boundaries

shield / basic volcanoes

broad volcano built up from the repeated eruption of basalt from constructive plate boundaries

rift valley

an area where a continent is being stretched and the central block moves downwards when two continental plates move away from each other

destructive(converging) plate boundary

when an oceanic plate and a continental plate / two oceanic plates / two continental plates move towards each other due to convection currents in the mantle forcing the oceanic plate to go down or subducted

slab pull / subduction

the force that causes the oceanic plate to sink below the other plate

subduction zone

a zone where the the oceanic plate is subducted

ocean trench

a depression of the ocean floor that runs parallel to a destructive plate boundary

benioff zone

a zone of earthquake foci in the upper part of a subducting oceanic plate at a destructive plate boundary

composite volcano

a volcano built up by alternating layers of layer and ash with a conical shape

acidic volcano

a volcano made up of lava with step sides and builds up into a convex cone shape

island arc

a chain of volcanoes that run parallel to an oceanic trench at a destructive plate boundary (oceanic - oceanic)

collision zone

a destructive plate boundary between two continental plates creating fold mountains