Download Disasters - Colyton High School

DISASTERS STUDY NOTES
DISASTERS ASSOCIATED WITH BOTH HUMAN AND NATURAL ACTIVITY
Thredbo Landslide
When it occurred: 1997
Where it occurred: Thredbo
Consequences of the disaster: 18 people died in the landslide
An inquiry into the disaster concluded that the landslide was a result of a leaking water pipe, and
that the N.S.W RTA and National Parks and Wildlife Services were at fault
MONITORING AND PREDICTING WEATHER PATTERNS
AIR PRESSURE: Air exerts pressure. The pressure of the atmosphere at any point is the weight of
air which lies vertically above the unit area. Air pressure decreases rapidly with height.
Hectopascals is the unit of air pressure. An aneroid barometer is used to measure air pressure.
WEATHER MAPS: Show how air pressure changes from place to place –usually sea level.
Isobars on weather maps join in places having the same atmospheric pressure. Isobars form high
(anti-clockwise) and lows (clockwise). Winds are strong when isobars are close together.
 High pressure system = fine weather
 Low pressure system = wet weather
 Slow moving cold front = light, sustained rainfall
 Rapid moving cold front = heavy rain or thunderstorm
MONITORING WEATHER PATTERNS BY RADAR AND LASER
The reflective properties of RADAR waves and LASER light allow instruments to scan the
atmosphere and increase the capability of modern weather forecasting.
RADAR: radio waves are transmitted and reflected from a range of materials, including:
raindrops and ice particles. The reflected wave patterns are picked up by a receiver and fed into
computers for analysis. Radar makes it possible to map the amount, movement and intensity of
precipitation, and therefore help to track storms. Radar waves are used to: observe cloud
formation, predict storm movements and measure variation of wind velocity. Rain and snow in
weather fronts hundreds of KMs away can be seen using Radar.
LASER/LIDAR- are also transmitted and reflected from weather fronts and the reflected
patterns are fed into computers. Laser spectroscopy is used in pollution monitoring. Lidar is
similar to Radar technology currently used for wind speed determination; however it uses higher
frequency EM waves (light), allowing it to determine wind characteristics in clear conditions.
ENERGY TRANSFERS AND TRANSFORMATIONS
BUSHFIRE: chemical potential energy  heat energy  light and sound energy
WARNING DEVICE: light energy  electrical energy  sound energy
FORMATION OF TROPICAL CYCLONES AND TORNADOES
Cyclones and tornadoes are examples of extremely violent storms produced by large differences
in air pressure. They are formed when:
 An area experiences extremely low air pressure
 They are produced by extreme differences in air pressure
 Often form over water and then move on to land
Body waves: Primary-WAVES AND Secondary-WAVES
The difference in time between the arrivals of the two waves allows for the focal point of the
earthquake to be located. *look at UNITS (eg/ km>m when ‘x’Ms..x1000). *convert difference
into time…eg/ 60
RICHTER SCALE
Provides quantative data as it corresponds with the amount of energy released in an earthquake.
The magnitude can range from 0-8.9 on the Richter scale.
MAGNITUDE QUANTATIVE DESCRIPTION
Minor
3.0 – 3.9
Light
4.0 – 4.9
Moderate
5.0 – 5.9
Strong
6.0 – 6.9
Major
7.0 – 7.9
MERCALLI SCALE
Is based on qualitative data only; as it is purely descriptive in nature (eg: catastrophic). It is an
intensity scale based on the sensation of vibration felt by the observer and the amount of damage
caused. A roman numeral between I and XXII is used to rate the damage.
I
Not felt by humans
II
Felt by a few indoor (upper floor)
III
Felt slightly

VII
General alarm, difficulty in standing,
trees and bushes strongly shaken.
BUSHFIRES The speed of a bushfire depends on:
 Incline/ slope- fire travels slower downhill and faster uphill, as hot air dries the
vegetation in front of it, providing fuel. As the slope increases, the flames are carried
closer to the fuel.
 Wind speed- in high winds, fire can ‘jump’. The wind also carries embers ahead.
Flammable vegetation- eucalyptus, forest litter, many native trees and shrubs contain chemicals
in their sap which are very flammable.
CONTROLLED BURNS AND BACKBURNS REDUCE RISK OF BUSHFIRE
The planned use of fire under selected weather and fuel conditions is called ‘prescribed’ or
‘preventative’ burning. This aims to reduce the load of fuel on the grounds so that when a natural
bushfire breaks out, the effects are more controllable. ‘Fire breaks’ and ‘access trails’ are strips
of land cleared of fuel to provide access for fire control purposes.
Controlled burns: a fire is lit and watched carefully as it burns (it is kept small). The job of the
fire is to burn up all the plant material which may pose a risk in summer, to minimise fuel.
Back-burns: a fire is lit a small distance in front of the main fire. This fire is meant to use up fuel
as the fire approaches. The wind generated from the back-burn draws the flames and heat of the
backfire into itself. As the main fire and the back-burn join together, the fire runs out of fuel and
can be brought under control.
NATURAL RESOUCES TO RETARD PROGRESS OF FIRE
The conditions of fry weather, high temperatures, strong wind, low humidity, and dry vegetation
NATURAL RESOURCES ARE:
 Water: pumped from tankers and backpacks, or dropped from the air by helicopters,
fixed-wing aircraft and water scooping air tankers.
 Fire retardant plants: moist eucalyptus forests and rain forests, swamp oak and river
oak, angopheras, bush box and cedar wattle.
MINIMISING THE LIKELIHOOD OF DAMAGE BY BUSHFIRES
Planting non-flammable vegetation, store flammable liquids (petrol) in metal containers, clearing
litter, gutters and wood piles, fire-proofing houses (sub-flooring, wire screens, enclosing eaves),
installing a separate water tank and pump in low water pressure areas, prepared clothing + hoses.