# Earthquakes!!

#### What do you know about earthquakes?  Let’s find out!

##### 1. Earthquakes usually happen at the edge of tectonic plates.
• Tectonic plates are the outer layer of the Earth.
• They are made of rock and are constantly moving.
##### 2. Earthquakes occur when the plates get stuck, but keep trying to move!
• The tectonic plates are constantly moving but sometimes they get stuck.
• When they get stuck, pressure builds up and the plates will suddenly move.
##### 3. Before an earthquake, foreshocks might occur!
• Foreshocks can be one or more small earthquakes which happen in the lead up to a bigger one, which is known as the main shock.
• Scientists can often use these to predict big earthquakes.
##### 4. After an earthquake, aftershocks are likely to happen.
• An aftershock is one or more small earthquakes after the main one has occurred.
• This is because of the Earth’s crust adjusting to the effect of the main earthquake.
• They can be very dangerous as buildings might already have damage to them from the large earthquake and so it can often cause them to fall.
##### 5. The shock waves that travel through the ground are called seismic waves.
• They are very strong at the centre of the earthquake.
• The waves travel to the surface and this is when the ground shakes and destruction happens.
##### 6. Scientists use the Moment Magnitude scale to measure how strong an earthquake is.
• This scale measures the energy that is released by the earthquake which makes it very accurate.
• In the past, scientists used something called the Richter scale which measured the size of the seismic waves, however, this wasn’t as accurate as it could have been.
##### 7. The place where an earthquake starts is called the hypocenter.
• An earthquake has to start somewhere!
• It is always under ground, below the Earth’s surface.
##### 8. The ground above where an earthquake starts is called the epicenter.
• The epicenter of an earthquake is on the ground directly above the hypocenter.
• The difference between them is the hypocenter is under the ground and the epicenter is above the ground.
##### 9. The strongest ever earthquake was in Chile, in the year 1960.
• It was a 9.5 on the Moment magnitude scale which is very, very high.
• The earthquake lasted for 10 whole minutes.
##### 10. Japan is the country where most earthquakes occur.
• This is because Japan is within something known as ‘The Pacific Ring of Fire’.
• This is on the edge of the Pacific Ocean and is where there is a tectonic plate edge.
• Other countries that are affected are Philippines, United States, Chile and more.