Earthquakes - Senior Library collection
How the Earth was made [videorecording]
ASIN B00126808K
Volcano [kit]
Discover the power of volcanoes and earthquakes-- from hot spots to tsunamis.
Natural disasters
Natural Disasters details the most catastrophic events that have shocked the world since history began. These are events that people have no control over - the sheer power of monster waves, booming avalanches and raging bushfires. Discover how rescue teams operate, and how experts try to predict and prevent disaster.
Countdown to disaster : the world in danger!
The world is in danger! From gigantic eruptions to asteroid collisions natural disasters have the power to devastate life on Earth. Find out why these disasters occur, what effects they have on our surroundings and how likely each disaster is to strike again. Find out what we are doing to avoid disasters in the future, and how people are learning to live with the threat of an earthquake or volcano on their doorstep.
Earthquakes Ian Graham
Describing how and why earthquakes occur, this text introduces geological science and the use of seismology to detect movement beneath the earth's surface. Topics include famous earthquakes of the past, the anatomy of a quake, the behaviour of tsunamis, and new techniques for detecting tremors with satellites.
Earthquakes and Tsunamis
Offering examples of beauty and danger this book will help readers experience and understand the full awesome power of nature and our Earth.
What is an earthquake?
An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's plates (plate tectonics). Earthquakes can happen along any type of plate boundary.
Earthquakes occur when tension is released from inside the crust. Plates do not always move smoothly alongside each other and sometimes get stuck. When this happens pressure builds up. When this pressure is eventually released, an earthquake tends to occur.
The effects of an earthquake can be devastating - they can destroy settlements, change landscapes, and cause many deaths.
What is the focus and epicentre of an earthquake?
The point inside the crust where the pressure is released is called the focus (or hypocenter). The point on the Earth's surface above the focus is called the epicentre.
Earthquake energy is released in seismic waves. These waves spread out from the focus. The waves are felt most strongly at the epicentre, becoming less strong as they travel further away. The most severe damage caused by an earthquake will happen close to the epicentre.
What are the seismic waves of an earthquake?
Earthquake energy is released in seismic waves. These waves spread out from the focus. The waves are felt most strongly at the epicentre, becoming less strong as they travel further away.
Properties of seismic waves
| p-waves | s-waves | |
|---|---|---|
| Type of wave | longitudinal | transverse |
| Relative speed | faster | slower |
| What can they travel through? | solids and liquids | solids only |
P-waves are longitudinal waves like sound waves, and s-waves are transverse waves like light waves.
The most severe damage caused by an earthquake will happen close to the epicentre.
Test your knowledge about earthquakes!
How to measure earthquakes?
The size of an earthquake is measured on a Richter scale 0-10 of magnitude using an instrument called a "seismograph". Seismographs are basically pens suspended over a paper-covered rotating drum. When the earth trembles the pen makes a larger squiggle on the drum, allowing the size of the shaking to be measured. Each whole number on the Richter scale represents an earthquake 30 times larger than the number below it. Earthquakes that measure less than 3.0 are not usually felt, while one of 5.0 produces the same amount of energy as the Hiroshima atomic bomb. Earthquakes measuring around 7 or 8 on the Richter scale can be devastating. The largest recorded quake happened in Chile in 1960 and measured 9.5.
Impact of earthquakes
Earthquakes can destroy settlements and kill many people. Effects of earthquakes are often classified as primary and secondary impacts. Primary effects occur as a direct result of the ground shaking, eg buildings collapsing. Secondary effects occur as a result of the primary effects, eg tsunamis or fires due to ruptured gas mains. It is also possible to classify the impacts of an earthquake by taking the following factors into account:
| Social impacts | Economic impacts | Environmental impacts | |
|---|---|---|---|
| Short-term (immediate) impacts | People may be killed or injured. Homes may be destroyed. Transport and communication links may be disrupted. Water pipes may burst and water supplies may be contaminated. | Shops and business may be destroyed. Looting may take place. The damage to transport and communication links can make trade difficult. | The built landscape may be destroyed. Fires can spread due to gas pipe explosions. Fires can damage areas of woodland. Landslides may occur. Tsunamis may cause flooding in coastal areas. |
| Long-term impacts | Disease may spread. People may have to be re-housed, sometimes in refugee camps. | The cost of rebuilding a settlement is high. Investment in the area may be focused only on repairing the damage caused by the earthquake. Income could be lost. | Important natural and human landmarks may be lost. |
Earthquake safety
BEFORE AN EARTHQUAKE:
- Have a disaster plan.
- Choose a safe place in every room. It’s best to get under a sturdy piece of furniture like a table or a desk where nothing can fall on you.
- Practice DROP, COVER AND HOLD ON! Drop under something sturdy, hold on, and protect your eyes by pressing your face against your arm.
- If you live in an earthquake prone area, bolt tall furniture to the wall and install strong latches to cupboards.
- Prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food and a can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water.
DURING AN EARTHQUAKE:
- DROP, COVER AND HOLD ON!
- Stay indoors until the shaking stops.
- Stay away from windows.
- If you’re in bed, hold on and stay there, protecting your head with a pillow.
- If you’re outdoors, find a clear spot away from buildings, trees and power lines. Then, drop to the ground.
- If you’re in a car, slow down and drive to a safe place. Stay in the car until the shaking stops.
AFTER THE SHAKING STOPS:
- Check for injuries.
- Inspect your home for damage.
- Eliminate fire hazards, so turn off the gas if you think its leaking.
- Expect aftershocks. Each time you feel one, DROP, COVER AND HOLD ON.
Can earthquakes be predicted?
Scientists have tried many different ways of predicting earthquakes, but none have been successful. One basic idea behind quake prediction is that faults send out subtle but detectable warnings before they slip. Scientists have looked at a host of potential warning signals, or "precursors," including foreshocks, weird animal behavior, and changes in the water table, stream flow, well levels, and patterns of electrical currents in the ground. However, on any particular fault, scientists know there will be another earthquake sometime in the future, but they have no way of telling when it will happen.
Case studies of destructive earthquakes
You need to learn the causes and consequence of some major earthquakes from case studies. Click the images or links below to go to the case studies.
The Haiti earthquake
At 4:53 pm on January 12 2010, the worst earthquake to hit the Caribbean in 200 years struck the impoverished nation of Haiti. The epicentre of the 7.0-magnitude earthquake was only 25 kilometres from the country’s capital, Port-au-Prince. The damage was massive and immediate, with the death toll to reach 230,000.
What decisions would you make as an earthquake survivor, aid worker, or journalist in Haiti after the earthquake? Inside the Haiti Earthquake is a first-person simulation based on documentary footage from Haiti and real-life decision scenarios. Try it now below to obtain your first hand experience about the devastating earthquake.