Editing Earthquake (section)

===Frequency===
[[File:Comerio, Luca (1878-1940) - Vittime del terremoto di Messina (dicembre 1908).jpg|thumb|The [[1908 Messina earthquake|Messina earthquake]] and tsunami took about 80,000 lives on December 28, 1908, in [[Sicily]] and [[Calabria]].<ref name="CFTI5">{{Cite web |url=https://storing.ingv.it/cfti/cfti5/quake.php?21318IT |title=1908 12 28, 04:20:27 Calabria meridionale-Messina (Italy)  |last1=Guidoboni E. |last2= Ferrari G. |website=CFTI5 Catalogue of Strong Earthquakes in Italy (461 BC – 1997) and Mediterranean Area (760 B.C. – 1500) |last3=Mariotti D. |last4=Comastri A. |last5=Tarabusi G. |last6=Sgattoni G. |last7=Valensise G}}</ref>]]

It is estimated that around 500,000 earthquakes occur each year, detectable with current instrumentation. About 100,000 of these can be felt.<ref name="usgsfacts">{{cite web|url=https://www.usgs.gov/natural-hazards/earthquake-hazards/science/cool-earthquake-facts|title=Cool Earthquake Facts|publisher=United States Geological Survey|access-date=2021-04-21|archive-date=2021-04-20|archive-url=https://web.archive.org/web/20210420165152/https://www.usgs.gov/natural-hazards/earthquake-hazards/science/cool-earthquake-facts|url-status=live}}</ref><ref name="wp100414">{{Cite news | first=Margaret Webb | last=Pressler | title=More earthquakes than usual? Not really. | department=KidsPost | newspaper= The Washington Post| pages= C10 | date=14 April 2010 }}</ref><!----url does not contain box statistics that print edition does and is included for info only----> Minor earthquakes occur very frequently around the world in places like California and Alaska in the U.S., as well as in El Salvador, Mexico, Guatemala, Chile, Peru, Indonesia, the Philippines, Iran, Pakistan, the [[Azores]] in Portugal, Turkey, New Zealand, Greece, Italy, India, Nepal, and Japan.<ref>{{cite web |url=https://earthquake.usgs.gov/ |title=Earthquake Hazards Program |publisher=United States Geological Survey |access-date=2006-08-14 |archive-date=2011-05-13 |archive-url=https://web.archive.org/web/20110513032733/https://earthquake.usgs.gov/ |url-status=live }}</ref> Larger earthquakes occur less frequently, the relationship being [[Gutenberg–Richter law|exponential]]; for example, roughly ten times as many earthquakes larger than magnitude 4 occur than earthquakes larger than magnitude 5.<ref>{{Cite web|url=https://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php|archiveurl=https://web.archive.org/web/20100524161817/http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php|url-status=dead|title=USGS Earthquake statistics table based on data since 1900|archivedate=May 24, 2010}}</ref> In the (low seismicity) United Kingdom, for example, it has been calculated that the average recurrences are:
an earthquake of 3.7–4.6 every year, an earthquake of 4.7–5.5 every 10&nbsp;years, and an earthquake of 5.6 or larger every 100&nbsp;years.<ref>{{cite web |url=http://www.quakes.bgs.ac.uk/hazard/Hazard_UK.htm |title=Seismicity and earthquake hazard in the UK |publisher=Quakes.bgs.ac.uk |access-date=2010-08-23 |archive-date=2010-11-06 |archive-url=https://web.archive.org/web/20101106121058/http://quakes.bgs.ac.uk/hazard/Hazard_UK.htm |url-status=live }}</ref> This is an example of the [[Gutenberg–Richter law]].

The number of seismic stations has increased from about 350 in 1931 to many thousands today. As a result, many more earthquakes are reported than in the past, but this is because of the vast improvement in instrumentation, rather than an increase in the number of earthquakes. The [[United States Geological Survey]] (USGS) estimates that, since 1900, there have been an average of 18 major earthquakes (magnitude 7.0–7.9) and one great earthquake (magnitude 8.0 or greater) per year, and that this average has been relatively stable.<ref>
{{cite web
 |title       = Common Myths about Earthquakes
 |url         = https://earthquake.usgs.gov/learning/faq.php?categoryID=6&faqID=110
 |publisher   = United States Geological Survey
 |access-date  = 2006-08-14
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20060925135349/http://earthquake.usgs.gov/learning/faq.php?categoryID=6&faqID=110
 |archive-date = 2006-09-25
}}</ref> In recent years, the number of major earthquakes per year has decreased, though this is probably a statistical fluctuation rather than a systematic trend.<ref>[https://earthquake.usgs.gov/learn/topics/increase_in_earthquakes.php Are Earthquakes Really on the Increase?] {{webarchive|url=https://web.archive.org/web/20140630233346/http://earthquake.usgs.gov/learn/topics/increase_in_earthquakes.php |date=2014-06-30 }}, USGS Science of Changing World. Retrieved 30 May 2014.</ref> More detailed statistics on the size and frequency of earthquakes is available from the United States Geological Survey.<ref>
{{cite web
 |title=Earthquake Facts and Statistics: Are earthquakes increasing?
 |url=http://neic.usgs.gov/neis/eqlists/eqstats.html
 |publisher=United States Geological Survey
 |access-date=2006-08-14
 |url-status=dead
 |archive-url=https://web.archive.org/web/20060812060818/http://neic.usgs.gov/neis/eqlists/eqstats.html
 |archive-date=2006-08-12
}}</ref> A recent increase in the number of major earthquakes has been noted, which could be explained by a cyclical pattern of periods of intense tectonic activity, interspersed with longer periods of low intensity. However, accurate recordings of earthquakes only began in the early 1900s, so it is too early to categorically state that this is the case.<ref>[http://www.australiangeographic.com.au/journal/the-10-biggest-earthquakes-in-recorded-history.htm/ The 10 biggest earthquakes in history] {{Webarchive|url=https://web.archive.org/web/20130930084024/http://www.australiangeographic.com.au/journal/the-10-biggest-earthquakes-in-recorded-history.htm/ |date=2013-09-30 }}, Australian Geographic, March 14, 2011.</ref>

Most of the world's earthquakes (90%, and 81% of the largest) take place in the {{convert|40000|km|mi|adj=mid|-long}}, horseshoe-shaped zone called the circum-Pacific seismic belt, known as the Pacific [[Ring of Fire]], which for the most part bounds the [[Pacific plate]].<ref>
{{cite web
 |title       = Historic Earthquakes and Earthquake Statistics: Where do earthquakes occur?
 |url         = https://earthquake.usgs.gov/learning/faq.php?categoryID=11&faqID=95
 |publisher   = United States Geological Survey
 |access-date  = 2006-08-14
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20060925142008/http://earthquake.usgs.gov/learning/faq.php?categoryID=11&faqID=95
 |archive-date = 2006-09-25
}}</ref><ref>
{{cite web
 |url         = https://earthquake.usgs.gov/learning/glossary.php?termID=150
 |publisher   = United States Geological Survey
 |title       = Visual Glossary – Ring of Fire
 |access-date  = 2006-08-14
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20060828152638/http://earthquake.usgs.gov/learning/glossary.php?termID=150
 |archive-date = 2006-08-28
}}</ref> Massive earthquakes tend to occur along other plate boundaries too, such as along the [[Himalayan Mountains]].<ref>{{cite journal | last1 = Jackson | first1 = James | year = 2006 | title = Fatal attraction: living with earthquakes, the growth of villages into megacities, and earthquake vulnerability in the modern world | url = http://rsta.royalsocietypublishing.org/content/364/1845/1911.full | journal = [[Philosophical Transactions of the Royal Society]] | volume = 364 | issue = 1845 | pages = 1911–1925 | doi = 10.1098/rsta.2006.1805 | pmid = 16844641 | bibcode = 2006RSPTA.364.1911J | s2cid = 40712253 | access-date = 2011-03-09 | archive-date = 2013-09-03 | archive-url = https://web.archive.org/web/20130903085953/http://rsta.royalsocietypublishing.org/content/364/1845/1911.full | url-status = live }}</ref>

With the rapid growth of [[Megacity|mega-cities]] such as Mexico City, Tokyo, and Tehran in areas of high [[seismic risk]], some seismologists are warning that a single earthquake may claim the lives of up to three million people.<ref>"[http://cires.colorado.edu/~bilham/UrbanEarthquakesGlobal.html Global urban seismic risk] {{Webarchive|url=https://web.archive.org/web/20110920015358/http://cires.colorado.edu/~bilham/UrbanEarthquakesGlobal.html |date=2011-09-20 }}." Cooperative Institute for Research in Environmental Science.</ref>