Hazardous Environments Flashcards
Natural hazard
A natural event (for example earthquake, flood, landslide, volcanic eruption) that
threatens or causes damage, destruction and death
Natural disaster
The results of a natural hazard taking place, such as deaths, injuries and destruction
of property.
Volcano
An opening in the Earth’s crust out of which lava, ash and gases erupt
Earthquake
violent shaking of the Earth’s crust
tropical cyclone
a weather system of very low pressure formed over tropical seas and involving
strong winds and heavy rainfall
risk
the potential of the hazard to do harm
plate boundaries
these are where tectonic plates meet.
Tectonic plate
A rigid segment of the Earth’s crust which can ‘float’ across the heavier, semi‐molten rock below. Continental plates are less dense, but thicker than oceanic plates.
Movement occurs
crust
the outermost layer of Earth, made of solid rocks
mantle
layer within the Earth between the crust and the core. It is composed
of mostly molten rocks.
Convection currents
occur within the molten rock in the mantle, act like a conveyor belt moving the tectonic plates above.
Conservative plate boundary
The plates are slipping past each other, either in the opposite direction, or in the same direction but at different rates. The plates do not pass each other smoothly. Also referred to as a transform plate boundary.
Destructive plate boundary
The plates are moving towards each other. Usually a continental plate and an oceanic plate, with the denser oceanic plate being forced underneath the
continental plate
Constructive plate boundary
The plates are moving apart from one another. Also known as a divergent plate boundary.
Collision plate boundary
Where two continental crusts collide. As they are of similar density, neither can sink, instead they push into each other forming mountains
hot spot
is a plume of magma that rises vertically through the mantle. The magma pushes
through the crust forming shield volcanoes.
sheild volcano
a gently sloped (shield-shaped) volcano, formed by the cooling of low viscosity (‘runny’) lava. Gentle eruptions and typically not dangerous
Composite volcano / stratovolcanoes.
steep-sided volcano formed by a sequence of explosive eruptions. Can be highly explosive and dangerous.
VEI
the Volcanic Explosivity Index is a relative measure of the explosiveness of volcanic
eruptions.
lava flows
streams of lava that have erupted from a volcano onto the Earth’s surface
Ash
small particles of rock and volcanic glass that land after a volcanic eruption has blasted them into the air.
Gas eruptions
when volcanic gases (including water vapour, carbon dioxide and sulphur
dioxide) that were dissolved in the magma are released into the atmosphere during an eruption.
pyroclastic flows
a mixture of dense hot rock, lava, ash and gases ejected from a volcano, which move very quickly across the Earth’s surface
Lahars
masses of rock, mud and water that travel quickly down the sides of a
volcano