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
Tsunami
a series of larger-than-normal waves, which are usually caused by volcanic eruptions or underwater earthquakes
Vulnerability
the potential of a human society to be harmed, by a natural hazard event.
primary impacts
are caused directly by the products of a volcanic eruption, e.g. a lava flow
secondary impacts
are the knock-on consequences of the primary impacts, e.g. fire caused by lava flow
Lahars
masses of rock, mud and water that travel quickly down the sides of a
volcano
Tsunami
a series of larger-than-normal waves, which are usually caused by volcanic eruptions or underwater earthquakes
ITCZ
Intertropical convergence zone is a band of low pressure around the thermal equator. Associated with thunderstorms and heavy rain. Where trade winds meet,
and tropical cyclones originate.
Atmospheric pressure
(air pressure) weight of air pressing down on the Earth’s surface
current
(ocean current) describes the motion in the ocean
wind shear
the difference in wind speeds (and direction) at higher and lower altitudes
Coriolis force
the force created by the Earth’s rotation that deflects any object moving at the
Earth’s surface
developed country
Country with very high human development (VHHD)
Emerging country
country with high or medium human development (HMHD)
Developing country
Country with low human development (LHD), a poor country
saffir-Simpson
Scale
scale used to measure strength of tropical storm
storm surge
a rise in sea level caused by tropical cyclones. The storms produce strong winds that
push the sea to the shore. This can cause flooding.
Levee
a way of stopping a river flood. Soil or another material is used to build up the banks of the river
social impact
an impact which effects people, for example homelessness
economic impact
An impact that relates to money, for example businesses close
environmental impact
An impact which effects the environment, for example loss of wildlife.
diaster relief
immediate help given after a disaster, including the emergency response such as
firefighters and search and rescue teams.
aid
help given by more wealthy nations to less well‐off nations, mainly to encourage
development
infrastructure
The transport networks and the water, sewage and communications systems that are
vital to people and their settlements and businesses.
Disaster recovery
is the process of maintaining or re-establishing vital infrastructure and systems
following a disaster
Disaster appraisal
Involves looking back at a disaster and considers whether anything more could be done to reduce the impact if a similar event were to occur again
fault
A fracture between two blocks of rock, where movement occurs when rock is under pressure.
focus
The point inside the Earth’s crust from which the pressure is released when an earthquake occurs. Also called hypocentre
epicentre
The point on the Earth’s surface directly above the focus of an earthquake.
Seismic waves
Energy released during earthquake. Also called shock waves
Tourism
is when people travel away from home for pleasure. It is an important source of
employment
geothermal energy
Heat under the ground used to generate electricity.
fertile land
Land that has soils capable of producing lots of crops.
adjustment
People altering their behaviour to prepare for natural hazards and reduce their impact
monitoring
Recording physical changes, such as earthquake tremors around a volcano or tracking a hurricane by satellite, to help predict when and where a natural hazard might strike.
prediction
being able to say when and where a natural hazard will strike. This can be done, to
some extent for volcanic eruptions and hurricanes, but not for earthquakes
preparation
Actions taken before a hazard strikes to reduce its impact, such as educating people or improving building design
risk assessment
Judging the amount of damage an area might expect from any given hazard.
