When there are two blocks or plates on the Earth, and one slips past the other one in a fast motion, this is called a fault. The plates are called tectonic plates when the edges move or slip past another plate. It causes the Earth to shake because of all of the energy and friction that is moving. The energy turns into seismic waves that act like ripples in a pond, and this is why the Earth shakes.
When the Earth’s crust starts to slip, this can happens because two different pieces of the Earth’s surface will slip, and this will cause the shaking and the movement.
Earthquake Facts for kids:
- On average, there are 16 major earthquakes a year
- The strongest earthquake ever happened in Chili in 1960
- The deadliest earthquake happened in China, Jan. 23, 1556 killing over 800,000 people
- The largest earthquake in the U.S. was 9.2 happened in Alaska in 1964
- The effects of earthquakes are ground shaking, ground rupture, tremors, tsunamis
- The first seismoscope was created in 1751.
- The first wave that makes it to a location during an earthquake is called a P wave.
- When an earthquake happens on the moon it is called a moonquake.
- In the Pacific Ocean, there is a zone where many earthquakes happen. This is called the “Ring of Fire.”
- There are over 500,000 earthquakes in the world.
- 100,000 earthquakes that happen in the world can be felt.
- Around 100 earthquakes are earthquakes that cause damage.
- When an earthquake happens, it can cause bodies of water to swosh around, this is called a seiche.
- California has more than 10,000 earthquakes each year.
- The intensity of an earthquake is how much shaking the earthquake makes.
- Most earthquakes happen less than 50 miles from the surface of the Earth.
- Most earthquakes happen along the plate boundaries.
- The scientist’s John Michell described earthquakes as “shifting masses of rock miles below the surface.”
- Alaska has the most earthquakes in the United States.
- Florida and North Dakota have the least number of earthquakes in the United States.
- The earthquake that killed most people happened in China with more than 250,000 people killed.
- Antarctica has icequakes that are like earthquakes, but they happen in ice instead of on land.
What Types of Earthquakes Are There?
There are four different types of earthquakes:
- Explosion earthquakes-these happen when there are nuclear or chemical devices that go off and cause the earth to quake.
- Tectonic earthquakes-these happen when the crust of the Earth breaks and causes physical changes to happen and energy waves to move rocks and plates.
- Volcanic earthquakes-Volcanic eruption happens when volcanic activity happens and causes the Earth to shake.
- Collapse earthquakes-collapse earthquakes are when earthquakes happen underground, and waves cause the rock surface to explode.
Why Do Earthquake’s Happen?
The Earth’s surface is made up of different plates.
The Earth is continually moving, and the plates of the Earth’s surface are continuously moving and shifting.
When these rocks move and shift, they cause the Earth to quake.
The stress on the Earth causes a natural disaster when the plates move, and when this happens, the shaking helps the crust to release some of the stress.
When enough stress is put on the Earth’s plates, some of the crust will break, and when they break happens, the shock dissipates through energy, and the energy moves in the form of waves throughout the Earth.
Where Do Earthquakes Start?
When an earthquake starts, it usually begins under the surface of the earth. This is called the hypocenter.
The place right above the hypocenter is the epicenter.
When an earthquake happens, it is strongest when it reaches the epicenter.
What Are the Earth’s Plates?
The Earth has large plates that are called tectonic plates.
These plates move all the time and even when the edges get stuck on other plates, they continue to move.
When the plates move, they build up the pressure because they become stuck on one another.
When the stress gets very strong, the plates will move quickly and send out a shock.
When the continents are moving around, this is called the Theory of the Plate Tectonics.
This theory says that there are many large, thin, and rigid plates that are all moving along with one another.
The plates move fast, slow, and in between and are all moving at different times and speeds.
The edges of the tectonic plates are called fault lines.
What Are Faults?
A fault is part of the area of the Earth where the plates slide back and forth past each other. These faults cause there to be cracks in the surface of the Earth.
There are four different types of faults:
- Dip-slip Faults
- Dip-slip Reverse Faults
- Strike-slip Faults
- Oblique-slip Faults
What is a Dip-Slip Fault?
A dip-slip fault is also called a normal fault.
This type of fault is a fault where part of it has moved from the top to the bottom. This happens when the plates extend.
What is a Dip-Slip Reverse Fault?
A dip-slip reverse fault is also called a thrust fault.
This fault happens when an upper block that is above the fault goes to the lower block. This happens when one plate is being pushed under another plate.
What is a Strike-Slip Fault?
A strike-slip fault is when there are two blocks in the fault that slide past each other.
There are two different types of strike-slip faults, the left-lateral strike-slip fault and the right-lateral strike-slip fault.
The left-lateral strike-slip fault is when the left black can be seen from either side.
The right-lateral strike-slip fault is when the block on the right can be seen from either side.
What is an Oblique-Slip Fault?
An oblique-slip fault has both dipping and strike characteristics.
This type of fault has to have both in order to be measured as an oblique-slip fault.
When an earthquake happens, there is a chance that there will be an aftershock.
An aftershock is a small earthquake that happens after a large earthquake.
These happen because the earthquake has caused there to be energy waves.
The leftover energy waves sometimes cause there to be more earthquakes, only smaller.
A tsunami is a string of fast-moving waves in the ocean caused by a powerful underwater earthquake.
Tsunami waves can inundate coastal areas causing widespread damage to homes, villages, and towns.
The tsunami early warning system (TWS) can help warn people of a potential wave reaching land so they have time to get to safety.
How Do Scientists Determine How Large an Earthquake Is?
When a scientist measures an earthquake, they use what is called seismic waves. A seismic wave is the shock waves that travel through the ground. The center of the earthquake has the strongest seismic waves.
Facts About Seismic Waves:
- Seismic waves travel more than 20 times the speed of sound.
- Seismic waves are measured with a seismograph.
- The size of a seismic wave is called magnitude.
- Scientists use the Moment Magnitude Scale to measure how strong an earthquake is.
- The Moment Magnitude Scale is also called the MMS scale.
- The larger the number on the MMS scale means the bigger the earthquake.
What is the Richter Scale?
The Richter Scale is one way that scientists measure how strong the earthquake is.
When the scale increases by one point, it means that there is ten times more shaking and more than 33 times more energy.
The Richter Scale is measured like this:
- Minor Earthquake -4
- Moderate Earthquake -5
- Strong Earthquake -6
- Major Earthquake -7
- Great Earthquake -8
What Should You Do If There is an Earthquake?
Earthquakes can be very dangerous, and it is important that you are prepared if you live in an area where earthquakes happen.
Here is what you need to do if there is an earthquake:
- Have a disaster plan.
- Make sure that you know where the safest place is in each of your rooms.
- Find a piece of furniture that is sturdy and get underneath it in case anything falls from the ceiling.
- Use the “Drop, cover and hold on” system. This means that you drop under something that is sturdy, you cover our head and your eyes and hold on until the earthquake is over.
- If you live in an area where there are a lot of earthquakes, you can bolt strong furniture to the walls so that they will not come down in an earthquake.
- Always have a first aid kit available.
- If you are outside, make sure that you are not under buildings, powerlines or trees.
- If you are in a vehicle, drive to somewhere safe and stay there until the earthquake is over.
Here is what you need to do after an earthquake:
- Check to see if you have any injuries or if anyone around you has any injuries.
- Check your home for any damages.
- Make sure there are no fires.
- Prepare for there to be other earthquakes or aftershock.
More information can be found on the U.S. Geological Survey website
What Did You Learn?
- How many types of earthquakes are there? There are four types of earthquakes; explosion earthquakes, tectonic earthquakes, volcanic earthquakes and collapse earthquakes.
- What is an earthquake? An earthquake is when different energy waves cause the Earth to shake or quake.
- What are faults? Faults are the place where plates slide back and forth against each other.
- How do scientists tell how big an earthquake is? Scientists can measure the seismic waves of an earthquake. They use MMS or Moment Magnitude System, or they use the Richter Scale to measure how big they are.
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