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== 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]]

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>

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 belt. It includes the seismic activities from [[Sumatra]], to the [[Himalayas]], to south Europe and north Africa, to the Atlantic Ocean.

The second part is the Alpide belt. It includes the seismic activities from [[Sumatra]], to the [[Himalayas]], to south Europe and north Africa, to the Atlantic Ocean.

== 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|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>

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]]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.

{{seealso|1976 Tangshan earthquake}}

{{seealso|1976 Tangshan earthquake}}

== EarthquakeEarthquake Clusters Media ==

== Earthquake Media ==

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File:Quake epicenters 1963-98.png|Earthquake [[epicenter]]s occur mostly along [[Plate tectonics|tectonic plate]] boundaries, especially on the Pacific [[Ring of Fire]].

File:Quake epicenters 1963-98.png|Earthquake [[epicenter]]s occur mostly along [[Plate tectonics|tectonic plate]] boundaries, especially on the Pacific [[Ring of Fire]].

File:Map of earthquakes 1900-.svg|Earthquakes (M6.0+) since 1900 through 2017

File:Map of earthquakes 1900-.svg|Earthquakes (M6.0+) since 1900 through 2017

File:Comerio, Luca (1878-1940) - Vittime del terremoto di Messina (dicembre 1908).jpg|The [[1908 Messina earthquake|Messina earthquake]] and tsunami took about 80,000 lives on December 28, 1908, in [[Sicily]] and [[Calabria]].

File:Comerio, Luca (1878-1940) - Vittime del terremoto di Messina (dicembre 1908).jpg|The [[1908 Messina earthquake|Messina earthquake]] and tsunami took about 80,000 lives on December 28, 1908, in [[Sicily]] and [[Calabria]].

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== Sources ==

== Sources ==