Earthquakes Flashcards
What is an earthquake?
An earthquake is the result of a sudden release of energy in the earth’s crust. The energy creates waves.
A wave that travels through the earth is called a SEISMIC WAVE.
These can be measured with a SEISMOMETER.
How do earthquakes happen?
- Plates on the earth’s crust move due to convection currents in the mantle.
- Plates try to move past each other and ‘stick’ which builds up tension and stress.
- When the force of the moving plate overcomes this tension, the resultant jolt or shock causes and earthquake.
What’s the focus and epicentre?
The focus is the point where the jolt happens underground.
The epicentre is the point on the surface immediately above the focus.
Short term effects of earthquakes.
- buildings collapse
- debris falling causing injury/death
- roads destroyed
- water and gas pipes burst
- electricity off
Long terms effects of earthquakes.
- people lose jobs
- mental trauma
- landslides
- tsunamis
- disease
Limiting the damage - Plan
- emergency services can practice for the disaster eg. Earthquake drill.
- stockpile medicines, food and blankets.
- educate the public about what to do during and after.
Limiting the damage - Protect
- construct buildings that can withstand shaking.
- eg. Include deep + firm building foundations + rubber shock absorbers beneath it.
- eg. Automatic shutters come down over the windows.
- eg. Rolling weights on the roof to counteract the shock waves.
Limiting the damage - Predict
-predicting earthquakes accurately enough to evacuate it is nearly impossible.
-some signs may be : water levels changing in wells + lakes
: small fore shocks potentially detected by a seismometer
: tilt meter to detect movement within a rock
Where did the Japan earthquake happen?
It happened off the Pacific coast of Tohoku, Japan.
When did the Japan earthquake happen?
It took place on 11th March 2011 at 2:46pm.
Why did the Japan earthquake happen?
It was caused by the sudden movement of the Pacific tectonic plate under the Eurasian plate with a 8.9 magnitude and a tsunami.
Who was affected by the Japan earthquake?
Around 20,000 deaths were recorded and 2,500 people missing.
What were the effects of the Japan earthquake?
The damage cost reached 25 trillion yen or £232 billion. Farms, factories, roads, railways + electricity lines were destroyed and almost half a million people were made homeless.
Buildings were then made earthquake proof with shock absorbers + deep foundations. Schools now do an earthquake drill every month.
