Changes

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 line]]s. An earthquake under the ocean can create a huge wave called a [[tsunami]]. Tsunamis can also cause a lot of destruction.

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 line]]s. An earthquake under the ocean can create a huge wave called a [[tsunami]]. Tsunamis can also cause a lot of destruction.

== Zones ==

== Zones ==

[[File:Map_of_earthquakes_1900-.svg|400px|thumb|Major earthquakes from 1900 to 2017]]

[[File:Map_of_earthquakes_1900-.svg|400px|thumb|Major earthquakes from 1900 to 2017]]

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

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

== History ==

== History ==

Earthquakes sometimes hit cities and kill hundreds or thousands of people. Most earthquakes happen along the [[Pacific Ring of Fire]] but the biggest ones mostly happen in other places. [[Tectonics|Tectonically]] active places are places where earthquakes or [[volcanic eruption]]s are regularly repeated.

Earthquakes sometimes hit cities and kill hundreds or thousands of people. Most earthquakes happen along the [[Pacific Ring of Fire]] but the biggest ones mostly happen in other places. [[Tectonics|Tectonically]] active places are places where earthquakes or [[volcanic eruption]]s are regularly repeated.

== Causes of an earthquake ==

== Causes of an earthquake ==

{{main|plate tectonics}}

{{main|plate tectonics}}

In areas of intense mining activity, often the roofs of underground mines collapse and minor tremors take place. These are called 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|Model of ancient [[seismometer]] with pendulum sensitive to ground tremors. In [[Luoyang]] in 133 AD, it detected an earthquake 400 to 500 km (250 to 310 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 AD, it detected an earthquake 400 to 500 km (250 to 310 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?|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>

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>

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>

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}}

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-proofing ==

== Earthquake-proofing ==

{{main|Earthquake engineering}}

{{main|Earthquake engineering}}

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 ==

<references/>

<references/>

== Other websites ==

== Other websites ==

{{Commons category|Earthquakes}}

{{Commons category|Earthquakes}}