What causes an earthquake?

Earthquake facts

  • There are more than one million earthquakes a year
  • Tectonic plates float on soft rock and are always moving
  • The plates rub against each other which causes friction and pressure
  • Plates slip and cause a jolt that we feel it as a sudden earthquake

Three boys walk with their father through streets ruined by an earthquake that struck Gunung Sitoli on Nias Island, Indonesia, in March 2005
Three boys walk with their father through streets ruined by an earthquake that struck Gunung Sitoli on Nias Island, Indonesia, in March 2005

What causes an earthquake?

Tectonic plates are floating on a bed of soft magma and rock below the earth's crust. Sometimes they move away from each other and sometimes they go towards another plate. When the plates touch they may rub against each other which causes friction.

This diagram shows the different tectonic plates on Earth. They are constantly moving and responsible for earthquakes
This diagram shows the different tectonic plates on Earth. They are constantly moving and responsible for earthquakes

The pressure builds up until one of the plates may no longer be able to withstand the force. The weaker plate slips out of position. It may even crack in places. Humans on the earth's surface feel this sudden movement and it is known as an earthquake.

The movement of the earth's crust is called seismic waves. The size of these seismic waves is measured on the Richter Scale.

Buildings destroyed by an earthquake that struck Beichuan in Sichuan Province, China, in May 2008
Buildings destroyed by an earthquake that struck Beichuan in Sichuan Province, China, in May 2008
Chinese soldiers walk over collapsed buildings in search of earthquake victims in Beichuan, China, in May, 2008
Chinese soldiers walk over collapsed buildings in search of earthquake victims in Beichuan, China, in May, 2008
A man looks over apartments destroyed by an earthquake in Beichuan county, Mianyang city, Sichuan province, China, in May, 2008
A man looks over apartments destroyed by an earthquake in Beichuan county, Mianyang city, Sichuan province, China, in May, 2008

How long do earthquakes last?

Earthquakes usually only last for a few seconds. However, earthquakes are often followed by a series of aftershocks. These are caused by the continued moving of the plates pushing against each other as they settle into their new positions. Aftershocks are never usually as powerful as the initial earthquake.

Sometimes where earthquakes happen below the sea they cause a tsunami.

What are the effects of an earthquake?

Earthquakes happen regularly and are fairly common in areas that lie on fault lines - the places where tectonic plates meet. One such area is Japan. The country may feel several earthquakes a year. However, the buildings have been designed to withstand minor tremors.

Earthquakes cause problems when they are very powerful. The force of the seismic waves causes buildings to shake. Sometimes the buildings will collapse. Over the years, many thousands of people have been killed when earthquakes have caused buildings to fall down.

A road in Asia is snapped by the force of a recent earthquake
A road in Asia is snapped by the force of a recent earthquake
Homes teeter on the edge of a cliff after an earthquake rocked this mountain village
Homes teeter on the edge of a cliff after an earthquake rocked this mountain village

Was the Japan 2011 earthquake caused by a supermoon

The earthquake that struck off the north east coast of Japan in March 2011 caused a killer tsunami that devastated the country.

But was the initial earthquake caused by a supermoon?

Experts had been warning just two days earlier that the movement of the moon could trigger unpredictable events and natural disasters on Earth.

The theory was that on March 19 the moon would be at its closest to the earth since 1922, some 221,567 miles away to be precise. They claimed that the gravitational pull of the moon would cause disruption on the earth.

The theory was giving added weight because only a few weeks earlier an earthquake had killed hundreds of people are destroyed buildings when it hit Christchurch in New Zealand.

Astrologer Richard Nolle first developed the supermoon theory in 1979.

He said that supermoons have a historical association with strong storms, very high tides, extreme tides and also earthquakes.

Scientists have, of course, dismissed the supermoon theories as nonsense, pointing out that Japan and New Zealand both have long histories of earthquakes and natural disasters.

January 2010

An earthquake hits Haiti in the Caribbean. It wrecked the nation, and it's thought to have killed between 100,000 and 200,000 people. Countless buildings were devastated and 1.5 million individuals were made homeless. Troops and support had to be sent in to help the recovery

April 2009

Around 150 individuals lost their lives in Italy when a quake struck in a metropolis called L'Aquila. More than 50,000 individuals were made homeless by the tremor.

May 2008

Around 87,000 people are thought to have died in China by when a quake struck the Sichuan region of the nation. Some five million homes were obliterated in the shudder which measured 7.5 on the Richter scale, and was the largest to strike the nation for 30 years.

August 2007

More than 450 individuals recorded dead in Peru by a tremor measuring 7.9 on the Richter scale.

May 2006

More than 3,000 people were left dead by a seismic tremor that struck the Indonesian island of Java. Something greater than 200,000 people were made homeless by the quake, which measured 6.2 on the Richter scale.

December 2004

The death count rose to 300,000 when a quake in the Indian Ocean measuring 9.0 on the Richter scale caused a colossal tsunami to hit some Asian nations. The worst affected nations were Indonesia, Sri Lanka, India and Thailand.

December 2003

An estimated 50,000 people were killed after a tremor in Iran, which measured 6.3 on the Richter scale.

May 2003

Over 1,000 folks are killed and practically 7,000 harmed in a shake in Algeria, which measured 6.7 on the Richter scale.

March 2002

Thousands lost their lives in a remote part of Afghanistan when a tremor measuring 6.0 on the Richter scale struck.

January 2001

Thirty-thousand individuals died and around 50,000 were seriously injured by an earthquake measuring 7.9 on the Richter scale in Gujarat, India.

January 2001

More than 1,000 residents died in a 7.2 quake in El Salvador.

Video: Earthquake causes

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Comments 3 comments

dilipchandra12 profile image

dilipchandra12 5 years ago from India

Handy useful information. Interesting aswell. Thanks for sharing :)


Rickrideshorses profile image

Rickrideshorses 5 years ago from England Author

Anytime dilipchandra12, glad you enjoyed.


Kate 3 years ago

The New Madrid fault line is fun in bad

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