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Disaster Dictionary
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P
Q | R | S | T | U | V | W | X | Y | Z
A
Affect large areas - heatwaves can affect many states at one time, like Victoria, New South Wales and Far-North Queensland.
After-shocks - smaller earthquakes that follow the first tremor.
Air pressure - rising air is called a low and sinking air called a high.
Alluvium - sediments such as sand and clay that have been dumped over time by streams and running water.
Ash clouds - tiny jagged particles of rock and natural glass blasted into the air by a volcano that can be blown by the wind for thousands of kilometres.
Asphyxiation - suffocation or insufficient intake of oxygen.
Avalanches - the slide of either snow, rock and mud or a combination of them.
B
Back burning - controlled burning of the bush or material that can easily be set alight. This is done so that when the dry summer arrives, there is less chance of a bushfire.
Bedrock - the solid rock that lies under the earth’s surface. It is made up of sand, soil and rocks.
C
Caldera - large craters that form when a volcano collapses.
Cinder Cone - piles of loose cinders that are produced by high lava fountains during an eruption.
Critical Infrastructure - the network of important systems that deliver essential services that people rely on. It includes water and sewerage, electricity and gas, telephones and transport.
D
Desalination - a process of removing salts and other minerals from seawater so that it can be used for drinking water.
Dormant volcanoes - a volcano which is presently inactive but could erupt again.
E
El Niņo weather pattern - causes a rise in sea temperature, weak easterly winds and the movement of rain clouds away from Australia.
Electrical storm - a storm that produces highly frequent lightning strikes.
Electrons - tiny particles that are capable of creating an electrical current.
Epicentre - the area above the focus of an earthquake.
Eruptions - when the pressure of the magma inside a volcano becomes so great that the volcano splits and the magma gets out.
F
Famines - a shortage of food in an entire community resulting from war or some natural disaster such as a drought.
Fire breaks - a gap that has no flammable materials (vegetation, dry grass or chemicals) that is used to stop or slow down a fire.
Fire front - the leading edge of a moving fire.
Flash flooding - results from relatively short, intense bursts of rainfall such as from severe storms.
G
Geography - the region of the Earth where we live that includes our natural environment, climate, vegetation and landforms.
Gradient - the steepness of land.
H
Habitat - the environment that provides an animal or plant with enough food, water, shelter, and living space.
Heat stress - when too much heat is absorbed by a person, animal or plant causing stress, illness or even death.
Heat stroke - happens when a person’s core body temperature rises above 40.5°C and the body’s internal systems start to shut down.
Humidity - a measure of how much or how little water vapour is in the air.
Hypothermia - when more heat escapes from your body than your body can produce. Severe hypothermia can lead to death.
I
Intra-plate earthquakes - Earthquakes that occur away from the plate boundaries.
J
K
L
Lahars - an Indonesian word describing mudflows and debris flows that originate from the slopes of a volcano.
Lava - molten rock that has erupted and reached the Earth’s surface.
Lava Dome - lava that piles up over the vent, rather than moving away as a lava flow.
Lava flows - can cause extensive damage or destruction by burning, crushing, or burying everything in their path.
M
Magma - hot molten rock and gasses that may emerge from an active volcano as lava.
Magnitude - the energy released by the earthquake.
Molten rock - a liquid that lies beneath the Earth’s surface and is made up of minerals and gasses. Molten rock can also be found in volcanoes.
Monsoonal (wet season) rains - seasonal winds that bring heavy rains, especially during the summer months in the northern parts of Australia.
Multicellular storms - a type of thunderstorm that is made up of many other storms. These storms produce severe hail and wind; can cause flash floods and weak tornadoes.
N
Northern Hemisphere - the half of the world above the equator. The northern hemisphere includes North America and Europe, along with most of Asia, northern South America and northern Africa.
O
P
Plate-margin earthquakes - earthquakes that are caused by the movement of neighboring tectonic plates.
Pyroclastic flows - can move at speeds of over 100 kilometres/hour and reach temperatures of over 400°C.
Q
R
Rainfall deciles - a system to measure average rainfall for an area. Rainfall can be measured as ‘above average’, ‘average’ or ‘below average’.
Richter Scale - is a standard scale used to compare earthquakes. The Richter scale measures on a factor of 10, so an earthquake of magnitude 4.0 is ten times more powerful than a magnitude 3.0 quake.
Ring of Fire - a series of volcanoes which surround the Pacific Ocean.
S
Seismic - movements in the Earth’s crust that are usually caused by earthquakes, explosions or volcanic eruptions.
Seismic waves - these are vibrations that travel out from where the stress is released. They can pass through water and land.
Seismograph - a device that is used to accurately record the motion of the ground during an earthquake.
Shield Volcano - have broad, gently sloping cones.
Southern Hemisphere - the half of the world below the equator. The southern hemisphere includes Australia, Antarctica, most of South America, and southern Africa.
Southern Oscillation Index - a way of measuring air pressure to predict if Australia is going to be either very wet, or very dry.
Stratovolcano - have steep-sided symmetrical cones.
Supercell thunderstorms - are long-lived thunderstorms with strong, swirling winds rotation within their cores. These storms produce very large hailstones, extreme wind gusts, powerful tornadoes and heavy rainfall.
T
Tectonic plates - part of the Earth’s crust that moves very slowly which causes changes in the positions of the continents.
Tropics - the area around the equator, between the Tropic of Cancer and the Tropic of Capricorn.
Tsunami - giant oceanic waves caused by an earthquake beneath the ocean, landslide or a volcanic eruption.
U
Underground aquifers - an underground layer of water-soaked sand and rock that acts as a water source.
Unpopulated - few or no people living in an area.
V
W
Water recycling - reusing waste water after it has been treated.
Water-bombing - helicopters and other aircraft with large buckets use water from pools, dams or lakes and dump it onto the fire from the air.
Wavelength - the distance between one peak of a wave and the peak of the next wave.
X
Y