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{{complex|date=November 2019}}

{{complex|date=November 2019}}

[[File:Sanfranciscoearthquake1906.jpg|thumb|250px|

[[File:Sanfranciscoearthquake1906.jpg|thumb|250px|

[[San Francisco]], [[California]] earthquake, sometime in 1960]]

[[San Francisco]], [[California]] earthquake, sometime in 1906]]

An '''earthquake''' is the sudden movement or trembling of the Earth's [[tectonic plates]], that creates the shakes of the ground. This shaking can destroy buildings and break the Earth's surface. Sudden shake under water is called tsunami.

An '''earthquake''' is when Earth's [[Plate tectonics|tectonic plates]] shake and move Earth's surface. Strong or high-magnitude earthquakes damage buildings.  

Who studies earthquakes is called [[seismology]].<ref name="camilla">{{cite book | title = Earth Science| publisher = Holt, Rinehart Winston| date = 2001| location = Austin, [[Texas]] 78746-6487| isbn = 0-03-055667-8}}</ref> There can be many earthquakes over a short period of time in a small area. The sudden release of tension in the [[tectonic plates]] sends waves of energy that travel through the Earth. [[Seismology]] studies about the cause, repeats, type and size of earthquakes.

Disturbances in the earth's balance cause earthquakes. Different tectonic plates are slowly moving around each other. When they get stuck, tension builds up in them. Earthquakes occur when tectonic plates suddenly break free, so they start moving very quickly. The first point of an earthquake's rupture is called its [[:en:Hypocenter|hypocenter]] or focus. The epicenter is the point at ground level directly above the hypocenter.

Earthquakes are measured using watching from [[seismograph]]s. The magnitude of an earthquake and the power of shaking is usually reported on the [[Richter scale]]. The Richter Scale was invented by Charles Francis Richter in 1935. On the scale, 2 is scarcely noticeable, and magnitude 5 (or more) creates damage over a wide area.

People who study earthquakes are called [[:en:Seismology|seismologists]]. Many earthquakes can occur in a small area in a short period of time. The sudden release of stress in the [[Plate tectonics|tectonic plates]] sends waves of energy that travel across the Earth. Seismology studies the cause, recurrence, type and magnitude of earthquakes.

An earthquake under the [[ocean]] can destruction as the earthquake itself in mountainous areas. Earthquakes can also create [[landslide]]s. Earthquakes are part of the Earth's natural [[rock cycle]]. The affect of an earthquake can be measured by a seismometer. It detects the shakes caused and it puts these movements on a seismograph. The strength, or magnitude, of an earthquake, is measured using the Richter scale. The Richter scale is numbered 0-9. The largest earthquake ever measured was a 9.5 on the scale a 10 has never been recorded.

The effect of an earthquake can be measured with a [[seismometer]]. A seismometer detects the tremors of the earth and plots the tremors on a seismograph. The strength or magnitude of an earthquake can be measured using the Richter scale. The Richter scale was invented by Charles Francis Richter in 1935. The scale is numbered 0-10. A 2 on this scale is a tremor that is not easily recorded. And damage of size 5 (or more) in a wide area. The largest earthquake ever measured had a magnitude of 9.5.

Scientists cannot predict an earthquake before it happens. But we do know where earthquakes might happen in the future, like close to [[fault (geology)|fault lines]]. An earthquake under the ocean can create a tsunami, this can create just as much destruction as the earthquake itself.

No one can tell when an earthquake will happen. But we know where earthquakes are likely to occur in the future, such as near fault lines. An earthquake under the ocean can create a huge wave called a tsunami. Tsunamis can also cause a lot of destruction.

 

Landslides can also cause earthquakes.

== Zones ==

== Zones ==

Earthquakes zones are divided into some parts of the world. The first is pacific belt. This part is the biggest part of seismic belt which means the largest activities of earthquakes caused by the movement of the earth's lithosphere as well as the volcanoes. The zone shape the most volcanoes located on the nations around the pacific ocean.<ref>{{Cite web|title=Earthquake Zones {{!}} Physical Geography|url=https://courses.lumenlearning.com/geophysical/chapter/earthquake-zones/|access-date=2021-07-09|website=courses.lumenlearning.com}}</ref>

Earthquake zones are concentrated in some parts of the world. The first is the [[Pacific Ring of Fire|Pacific belt]], which circles the Pacific Ocean. This part is the biggest seismic belt: it has the most active earthquakes and the most [[volcanoes]].<ref>{{Cite web|title=Earthquake Zones {{!}} Physical Geography|url=https://courses.lumenlearning.com/geophysical/chapter/earthquake-zones/|access-date=2021-07-09|website=courses.lumenlearning.com|archive-date=2021-07-09|archive-url=https://web.archive.org/web/20210709185442/https://courses.lumenlearning.com/geophysical/chapter/earthquake-zones/|url-status=live}}</ref>

 

The second part is the alpide. It is the seismic activities from [[Sumatra]], [[Himalayas|Himalayan]], europan to outer atlantic.  

These belts are along the edges of tectonic plates. The tectonic plates push on each other and make great amounts of tension.

== History ==

== History ==

== Causes of an earthquake ==

== Causes of an earthquake ==

{{main|plate tectonics}}

{{main|plate tectonics}}

Earthquakes are caused by tectonic movements in the Earth's crust. The main cause is when [[Plate tectonics|tectonic plates]] ride one over the other, causing [[orogeny]] (mountain building), and severe earthquakes.<ref>{{Cite web|title=Science of Earthquakes Seismic Zones|url=https://www.prfire.co.uk/press_releases/science-of-earthquakes-seismic-zones|access-date=2021-07-09|website=PR Fire|language=en-GB}}</ref>

Earthquakes are caused by tectonic movements in the Earth's crust. The main cause is when [[Plate tectonics|tectonic plates]] ride one over the other, causing [[orogeny]] (mountain building), and severe earthquakes.<ref>{{Cite web|title=Science of Earthquakes Seismic Zones|url=https://www.prfire.co.uk/press_releases/science-of-earthquakes-seismic-zones|access-date=2021-07-09|website=PR Fire|language=en-GB|archive-date=2021-07-09|archive-url=https://web.archive.org/web/20210709190848/https://www.prfire.co.uk/press_releases/science-of-earthquakes-seismic-zones|url-status=live}}</ref>

The boundaries between moving plates form the largest [[Fault (geology)|fault]] surfaces on Earth. When they stick, motion between the plates leads to increasing stress. This continues until the stress rises and breaks, suddenly allowing sliding over the locked portion of the fault. This releases the [[Potential energy|stored energy]] as [[shock wave]]<nowiki/>s. The [[San Andreas Fault|San Andreas fault]] in [[San Francisco]], and [[Great Rift Valley|Rift valley]] fault in [[Africa]] are faults like this.

The boundaries between moving plates form the largest [[Fault (geology)|fault]] surfaces on Earth. When they stick, motion between the plates leads to increasing stress. This continues until the stress rises and breaks, suddenly allowing sliding over the locked portion of the fault. This releases the [[Potential energy|stored energy]] as [[shock wave]]s. The [[San Andreas Fault|San Andreas fault]] in [[San Francisco]], and [[Great Rift Valley|Rift valley]] fault in [[Africa]] are faults like this.

1. Volcanic Earthquakes : Earthquakes which are caused by volcanic eruptions are quite devastating. However, these are confined to areas of active volcanoes.

1. Volcanic Earthquakes: Earthquakes which are caused by volcanic eruptions are quite devastating. However, these are confined to areas of active volcanoes.

2. Collapse Earthquakes : In areas of intense mining activity, often the roofs of underground mines collapse and minor tremors take place. These are called collapse earthquakes.

2. Collapse Earthquakes: In areas of intense mining activity, often the roofs of underground mines collapse and minor tremors take place. These are called collapse earthquakes.

== Earthquake fault types ==

== Earthquake fault types ==

[[File:EastHanSeismograph.JPG|thumb|Replica of ancient [[seismometer]] with pendulum sensitive to ground tremors. In [[Luoyang]] in 133&nbsp;AD, it detected an earthquake 400 to 500&nbsp;km (250 to 310&nbsp;mi) away|270x270px]]There are three main types of [[Fault (geology)|geological fault]] that may cause an earthquake: normal, reverse (thrust) and strike-slip. Normal faults occur mainly in areas where the crust is being extended. Reverse faults occur in areas where the crust is being shortened. Strike-slip faults are steep structures where the two sides of the [[Fault (geology)|fault]] slip horizontally past each other.

[[File:EastHanSeismograph.JPG|thumb|Model of ancient [[seismometer]] with pendulum sensitive to ground tremors. In [[Luoyang]] in 133&nbsp;AD, it detected an earthquake 400 to 500&nbsp;km (250 to 310&nbsp;mi) away|270x270px]]There are three main types of [[Fault (geology)|geological fault]] that may cause an earthquake: normal, reverse (thrust) and strike-slip. Normal faults occur mainly in areas where the crust is being extended. Reverse faults occur in areas where the crust is being shortened. Strike-slip faults are steep structures where the two sides of the [[Fault (geology)|fault]] slip horizontally past each other.

== Earthquake clusters ==

== Earthquake clusters ==

Most earthquakes form part of a sequence, related to each other in terms of location and time.<ref name=WAAFEC>{{Cite web|url=https://earthquake.usgs.gov/eqcenter/step/explain.php|title=What are aftershocks, foreshocks, and earthquake clusters?}}</ref> Most earthquake clusters consist of small tremors which cause little to no damage, but there is a theory that earthquakes can recur in a regular pattern.<ref>{{cite web|url=https://earthquake.usgs.gov/research/parkfield/repeat.php|title=Repeating earthquakes|publisher=[[United States Geological Survey]]|date=January 29, 2009|access-date=May 11, 2009}}</ref>

Most earthquakes form part of a sequence, related to each other in terms of location and time.<ref name=WAAFEC>{{Cite web|url=https://earthquake.usgs.gov/eqcenter/step/explain.php|title=What are aftershocks, foreshocks, and earthquake clusters?|access-date=2017-08-31|archive-date=2009-05-11|archive-url=https://web.archive.org/web/20090511175245/http://earthquake.usgs.gov/eqcenter/step/explain.php|url-status=dead}}</ref> Most earthquake clusters consist of small tremors which cause little to no damage, but there is a theory that earthquakes can recur in a regular pattern.<ref>{{cite web|url=https://earthquake.usgs.gov/research/parkfield/repeat.php|title=Repeating earthquakes|publisher=[[United States Geological Survey]]|date=January 29, 2009|access-date=May 11, 2009|archive-date=April 3, 2009|archive-url=https://web.archive.org/web/20090403074132/http://earthquake.usgs.gov/research/parkfield/repeat.php|url-status=dead}}</ref>

A '''foreshock''' is an earthquake that happens before a larger earthquake, called the mainshock.

A '''foreshock''' is an earthquake that happens before a larger earthquake, called the mainshock.

An '''aftershock''' is an earthquake that happens after a previous earthquake, the mainshock. An aftershock is in the same place of the main shock but always of a smaller magnitude. Aftershocks are formed as the crust adjusts to the effects of the main shock.<ref name=WAAFEC/>

An '''[[aftershock]]''' is an earthquake that happens after a previous earthquake, the mainshock. An aftershock is in the same place of the main shock but always of a smaller magnitude. Aftershocks are formed as the crust adjusts to the effects of the main shock.<ref name=WAAFEC/>

'''Earthquake swarms''' are sequences of earthquakes striking in a specific area within a short period of time. They are different from earthquakes followed by a series of aftershocks by the fact that no single earthquake in the sequence is obviously the main shock, therefore none have notably higher magnitudes than the other. An example of an earthquake swarm is the 2004 activity at [[Yellowstone National Park]].<ref>{{Cite web|url=http://volcanoes.usgs.gov/yvo/2004/Apr04Swarm.html|title=Earthquake swarms at Yellowstone|publisher=USGS|access-date=2008-09-15}}</ref>

'''Earthquake swarms''' are sequences of earthquakes striking in a specific area within a short period of time. They are different from earthquakes followed by a series of aftershocks by the fact that no single earthquake in the sequence is obviously the main shock, therefore none have notably higher magnitudes than the other. An example of an earthquake swarm is the 2004 activity at [[Yellowstone National Park]].<ref>{{Cite web|url=http://volcanoes.usgs.gov/yvo/2004/Apr04Swarm.html|title=Earthquake swarms at Yellowstone|publisher=USGS|access-date=2008-09-15|archive-date=2008-05-13|archive-url=https://web.archive.org/web/20080513060550/http://volcanoes.usgs.gov/yvo/2004/Apr04Swarm.html|url-status=live}}</ref>

Sometimes a series of earthquakes happen in a sort of '''earthquake storm''', where the earthquakes strike a fault in clusters, each triggered by the shaking or stress redistribution of the previous earthquakes. Similar to aftershocks but on adjacent segments of fault, these storms happen over the course of years, and with some of the later earthquakes as damaging as the early ones. Such a pattern happened in the North [[Anatolia]]n fault in [[Turkey]] in the 20th century.<ref>{{cite journal | title = Poseidon’s horses: plate tectonics and earthquake storms in the late Bronze Age Aegean and Eastern Mediterranean | journal = Journal of Archaeological Science | year = 2000 | author = Amos Nur | issn = 0305-4403 | volume = 27 | pages = 43–63 | url = http://water.stanford.edu/nur/EndBronzeage.pdf | doi = 10.1006/jasc.1999.0431 | access-date = 2010-06-17 | archive-date = 2009-03-25 | archive-url = https://web.archive.org/web/20090325050459/http://water.stanford.edu/nur/EndBronzeage.pdf | url-status = dead }}</ref><ref>{{cite web | url = http://www.bbc.co.uk/science/horizon/2003/earthquakestorms.shtml | title = Earthquake storms | work = Horizon (BBCtv series) | date = 1 April 2003 | access-date = 2007-05-02 }}</ref>

Sometimes a series of earthquakes happen in a sort of '''earthquake storm''', where the earthquakes strike a fault in clusters, each triggered by the shaking or stress redistribution of the previous earthquakes. Similar to aftershocks but on adjacent segments of fault, these storms happen over the course of years, and with some of the later earthquakes as damaging as the early ones. Such a pattern happened in the North [[Anatolia]]n fault in [[Turkey]] in the 20th century.<ref>{{cite journal | title = Poseidon's horses: plate tectonics and earthquake storms in the late Bronze Age Aegean and Eastern Mediterranean | journal = Journal of Archaeological Science | year = 2000 | author = Amos Nur | issn = 0305-4403 | volume = 27 | pages = 43–63 | url = http://water.stanford.edu/nur/EndBronzeage.pdf | doi = 10.1006/jasc.1999.0431 | access-date = 2010-06-17 | archive-date = 2009-03-25 | archive-url = https://web.archive.org/web/20090325050459/http://water.stanford.edu/nur/EndBronzeage.pdf | url-status = dead }}</ref><ref>{{cite web | url = http://www.bbc.co.uk/science/horizon/2003/earthquakestorms.shtml | title = Earthquake storms | work = Horizon (BBCtv series) | date = 1 April 2003 | access-date = 2007-05-02 | archive-date = 2019-10-16 | archive-url = https://web.archive.org/web/20191016045550/http://www.bbc.co.uk/science/horizon/2003/earthquakestorms.shtml | url-status = live }}</ref>

== Tsunami ==

== Tsunami ==

{{main|Tsunami}}

{{main|Tsunami}}

[[File:20110311Houshu.ogv|thumb|right|Animation of the 2011 Sendai [[tsunami]].]]

[[File:20110311Houshu.ogv|thumb|right|Animation of the 2011 Sendai [[tsunami]].]]

'''[[Tsunami]]''' or a [[chain]] of fast moving [[wave]]s in the [[ocean]] caused by powerful earthquakes is a very serious challenge for people's safety and for [[earthquake engineering]]. Those waves can [[inundate]] coastal areas, destroy [[house]]s and even swipe away whole [[town]]s.<ref>[https://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0001xgp.php USGS Poster of the Near the East Coast of Honshu, Japan Earthquake of 11 March 2011 - Magnitude 8.9]</ref> This is a danger for the whole mankind.

A '''[[tsunami]]''' is a [[chain]] of fast moving [[wave]]s in the [[ocean]] caused by powerful earthquakes. They are very serious challenges for people's safety and for [[earthquake engineering]]. Those waves can [[flood]] coastal areas, destroy [[house]]s and even swipe away whole [[town]]s.<ref>{{Cite web |url=https://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0001xgp.php |title=USGS Poster of the Near the East Coast of Honshu, Japan Earthquake of 11 March 2011 - Magnitude 8.9 |access-date=31 August 2017 |archive-date=11 March 2011 |archive-url=https://www.webcitation.org/5x7CSAr0G?url=http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0001xgp.php |url-status=dead }}</ref> This is a danger for the whole mankind.

Unfortunately, tsunamis cannot be prevented. However, there are [[Tsunami warning system|warning systems]]<ref>{{Cite web |url=http://ptwc.weather.gov/ |title=Pacific Tsunamy Warning Center |access-date=2021-01-18 |archive-date=2011-03-13 |archive-url=https://www.webcitation.org/5x8nAhhwJ?url=http://ptwc.weather.gov/ |url-status=dead }}</ref> which may warn the [[population]] before the big waves reach the [[land]] to let them enough time to rush to safety.

Unfortunately, tsunamis cannot be prevented. However, there are [[Tsunami warning system|warning systems]]<ref>{{Cite web |url=http://ptwc.weather.gov/ |title=Pacific Tsunamy Warning Center |access-date=2021-01-18 |archive-date=2011-03-13 |archive-url=https://www.webcitation.org/5x8nAhhwJ?url=http://ptwc.weather.gov/ |url-status=dead }}</ref> which may warn the [[population]] before the big waves reach the [[land]] to let them enough time to rush to safety.

Earthquake-proof buildings are constructed to withstand the destructive force of an earthquake. This depends upon its type of construction, shape, [[mass]] distribution, and [[wikt:rigid|rigidity]]. Different combinations are used. Square, rectangular, and shell-shaped buildings can withstand earthquakes better than [[skyscraper]]s. To reduce stress, a building's ground floor can be supported by extremely rigid, empty columns, while the rest of the building is supported by flexible columns inside the empty columns. Another method is to use rollers or rubber pads to separate the base columns from the ground, allowing the columns to shake parallel to each other during an earthquake.

Earthquake-proof buildings are constructed to withstand the destructive force of an earthquake. This depends upon its type of construction, shape, [[mass]] distribution, and [[wikt:rigid|rigidity]]. Different combinations are used. Square, rectangular, and shell-shaped buildings can withstand earthquakes better than [[skyscraper]]s. To reduce stress, a building's ground floor can be supported by extremely rigid, empty columns, while the rest of the building is supported by flexible columns inside the empty columns. Another method is to use rollers or rubber pads to separate the base columns from the ground, allowing the columns to shake parallel to each other during an earthquake.

To help prevent a roof from collapsing, builders make the roof out of light-weight materials. Outdoor walls are made with stronger and more reinforced materials such as steel or [[reinforced concrete]]. During an earthquake, flexible windows may help hold the windows together so they don’t break.

To help prevent a roof from collapsing, builders make the roof out of light-weight materials. Outdoor walls are made with stronger and more reinforced materials such as steel or [[reinforced concrete]]. During an earthquake, flexible windows may help hold the windows together so they don't break.

== Sources ==

== Sources ==

* [http://neic.usgs.gov/neis/eqlists/10maps_world.html USGS – Largest earthquakes in the world since 1900] {{Webarchive|url=https://web.archive.org/web/20090303054812/http://neic.usgs.gov/neis/eqlists/10maps_world.html |date=2009-03-03 }}

* [http://neic.usgs.gov/neis/eqlists/10maps_world.html USGS – Largest earthquakes in the world since 1900] {{Webarchive|url=https://web.archive.org/web/20090303054812/http://neic.usgs.gov/neis/eqlists/10maps_world.html |date=2009-03-03 }}

* [http://www.armageddononline.org/earthquake.php The Destruction of Earthquakes] {{Webarchive|url=https://web.archive.org/web/20090208004752/http://www.armageddononline.org/earthquake.php |date=2009-02-08 }} - a list of the worst earthquakes ever recorded

* [http://www.armageddononline.org/earthquake.php The Destruction of Earthquakes] {{Webarchive|url=https://web.archive.org/web/20090208004752/http://www.armageddononline.org/earthquake.php |date=2009-02-08 }} - a list of the worst earthquakes ever recorded

* [https://earthquake.usgs.gov/eqcenter/recenteqsww/ Recent Quakes WorldWide]

* [https://earthquake.usgs.gov/eqcenter/recenteqsww/ Recent Quakes WorldWide] {{Webarchive|url=https://web.archive.org/web/20170901125659/https://earthquake.usgs.gov/eqcenter/recenteqsww/ |date=2017-09-01 }}

* [http://en.citizendium.org/wiki/Earthquake Earthquake] Citizendium

* [http://en.citizendium.org/wiki/Earthquake Earthquake] Citizendium

* [http://www.emsc-csem.org/Earthquake/ Real Time Seismicity] European-Mediterranean Seismological Centre (EMSC)

* [http://www.emsc-csem.org/Earthquake/ Real Time Seismicity] European-Mediterranean Seismological Centre (EMSC)