Disaster Dictionary

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.
Arson
- the crime of intentionally and maliciously setting fire to buildings, wildland areas, vehicles or other property with teh intent to cause damage.
Ash clouds
- tiny jagged particles of rock and natural glass blasted into teh air by a volcano that can be blown by the wind for thousands of kilometres.
Asphyxiation
- suffocation or insufficiant 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.
Bubonic plague
- a contagious, often fatal, epidemic disease caused by the bacterium Yersinia pestis, transmitted by the bite of fleas from an infected rodent, especially a rat.

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.
Drawdown
- water receding from the shoreline before returning as a fast-moving wall of water.

E

El Niño 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

Influenza
- a viral infection of the respiratory system
Intra-plate earthquakes
- Earthquakes that occur away from the plate boundaries.

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.

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.

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.
Shoaling
- the bunching up of water that increases the wave height.
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.

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.