What Are Earthquakes

& How Do They Occour ?

What Are Earthquakes ?

Earthquakes are the vibrations caused by rocks breaking under stress. The underground surface along which the rock breaks and moves is called a fault plane. They cause violent shaking of the ground, sometimes triggering great destruction, as a result of movements within the earth's crust.

How Do Earthquakes Occur ?

An earthquake takes place when to blocks of the earth suddenly slip past one another. The surface where they slip is called a fault.

Sometimes earthquakes has fore shocks. These are smaller earthquakes that happen in the same place before a larger one takes place.

The largest main earthquake is called the main shock. Main shocks are always followed be aftershocks that occur in the same place & continue for weeks, months or even years after the main shock.

The earth has four major layers: inner core, outer core, mantle & crust. The crust & the top of the mantle make up a thin skin on the surface of your planet. But this skin is not all in one piece. It is made up of many pieces covering the surface of the earth.

These pieces are called tectonic plates, and the edges of the plates are called plate boundaries. These pieces keep on moving around slowly, sliding past one another & bumping in to each other. These plate boundaries are made up of many faults, and most earthquakes around the world occur on these faults.

While the edges of the faults are stuck together, & the rest of the block is moving, the energy that would normally cause the blocks to slide past one another is being accumulated.

When the force of the moving blocks finally overcomes the friction of the jagged edges of the fault and it beaks free, all of the stored up energy is released

The seismic wave shake the earth as they move through it, and when waves reach the earth’s surface, they shake the ground & anything on it, like our houses & us. The energy radiated outward from the fault in all directions in the form of seismic waves like ripples on a pond

Animation Of An Earthquake

Animation of Earthquake and Tsunami in Sumatra
Tsunami Generation Animation Generated by a Subduction Zone Earthquake

What Is The Government Doing To Prevent Earthquake Damage ?

Earthquakes cannot be prevented, but measures can be taken to increase the safety of people (earthquake proof buildings, earthquake warnings, earthquake safety information). Earthquakes tend to happen in places surrounded by tectonic plates or in places close to the edges of tectonic plates. Normally, people can be given a few minutes (about 20) warning before an earthquake happens as seismic activity will have been picked up by seismometers.

Research is still being done to find a way to predict when an earthquake will happen. Big earthquakes tend to happen if there has not been much seismic activity in an earthquake prone area for a long time, because a lot of tension has built up between the plates over time and so energy is released very suddenly.

Examples Of Earthquake Prevention

There are building structure techniques used in Japan (and several other countries, including the USA) that are designed to minimize earthquake damage as much as possible. Most of them have been shown to be effective.

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Taipei 101

An example of this is the Taipei 101, which is equipped with a tuned mass damper (as you can see in the photo). Taipei 101 is designed to withstand the typhoon winds and earthquake tremors common in its area of the Asia-Pacific.

Inside the Taipei 101 skyscraper in Taiwan is the world's largest and heaviest tuned mass damper. Essentially acting as a giant pendulum, the enormous steel sphere moves slightly back and forth to counter any motion of the building itself. It is an engineering marvel meant to limit the vibrations of the 1667-foot tall building.
Taipei 101 tuned mass damper moving during earthquakes

What To Do during An Earthquake

  • If you're indoors, stay there
  • Get under and hold onto a desk or table
  • If there are no tables or desks around, stand against an interior wall
  • Stay clear of, glass, heavy furniture, fireplaces and appliances.
  • The kitchen is a dangerous spot to be in during an earthquake
  • If you're outside, get into the open
  • Stay away of buildings, power lines or anything that could fall
  • If you're driving, stop the car, avoid parking under or on bridges or overpasses
  • Try to stay clear of trees, light posts, signs and power lines
  • If you are in a mountainous area, beware of land slides
  • If you are near the ocean, be aware that tsunamis are associated with large earthquakes. Get to high ground as quickly as possible.

How to be Prepared For An Earthquake

  • Electricity, water, gas and telephones may not be working after an earthquake. You should be prepared to fend for yourself for at least three days, preferably for a week
  • You will need food and water (4 litters a day per person)
  • A first aid kit
  • A fire extinguisher
  • Flashlights
  • A portable radio
  • Extra batteries
  • Blankets
  • Clothes and shoes
  • Money (ATMs may not work)
  • Medication
  • An substitute cooking source (barbecue or camp stove)

What To Do After An Earthquake

  • Check for fire or fire hazards
  • If the phone is working, only use it in case of emergency.
  • Check for cracks and damage to the roof and foundation of your home.
  • Listen to the radio for important information and instructions
  • If you leave home, leave a message telling friends and family your location.

What Are Some Primary, Secondary & Tertiary Effects Of An Earthquake


· Ground shaking

· Landslides

· Liquefaction

· Surface rupture

· Trees collapsing

· Buildings collapsing

· People buried in rubble

· School children trapped under collapsed schools

· Poorly built buildings toppling over


· Tsunami

· Seiche

· Flooding

· Fire

· Homelessness

· Need of emergency housing

· Households were inaccessible by road due to landslides

· Cracks in the ground and walls.

· Buildings split in two.

· Lots of rubble that takes years to move


· Disease spread, sourced from people drinking the dirty, contaminated water

· Food will be lost

· shortages of drinkable water from broken water lines

· lack of medical assistance due to broken transportation lines

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Created By : James Ivey