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Events with magnitudes greater than 4.5 are strong enough to be recorded by a seismograph anywhere in the world, so long as its sensors are not located in the earthquake's [[Shadow zone|shadow]].<ref>{{Cite journal|last=Brush|first=Stephen G.|date=September 1980|title=Discovery of the Earth's core|url=http://aapt.scitation.org/doi/10.1119/1.12026|journal=American Journal of Physics|language=en|volume=48|issue=9|pages=705–724|doi=10.1119/1.12026|issn=0002-9505}}</ref><ref>{{Cite book |title=A dictionary of earth sciences.|date=2008|author=Michael Allaby|isbn=978-0-19-921194-4|edition=3rd |location=Oxford|oclc=177509121}}</ref><ref>{{Cite journal|last=Einarsson|first=P.|date=September 1978|title=S-wave shadows in the Krafla Caldera in NE-Iceland, evidence for a magma chamber in the crust|url=http://dx.doi.org/10.1007/bf02597222|journal=Bulletin Volcanologique|volume=41|issue=3|pages=187–195|doi=10.1007/bf02597222|issn=0258-8900}}</ref>
The following describes the typical effects of earthquakes of various magnitudes near the epicenter.<ref name="GNSScience1">{{cite web | url=https://www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/Monitoring-Earthquakes/Other-earthquake-questions/What-is-the-Richter-Magnitude-Scale | title=What is the Richter Magnitude Scale? | publisher=[[GNS Science]] |
{| class="wikitable"
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|[[Microearthquake|Micro]]
|I
|Microearthquakes, not felt, or felt rarely. Recorded by seismographs.<ref>This is what Richter wrote in his ''Elementary Seismology'' (1958), an opinion copiously reproduced
|Continual/several million per year
|-
|2.0–2.9
|rowspan="
|I
|Felt slightly by some people. No damage to buildings.
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|-
|3.0–3.9
|II to III
|Often felt by people, but very rarely causes damage. Shaking of indoor objects can be noticeable.
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|Light
|IV to V
|Noticeable shaking of indoor objects and rattling noises. Felt by most people in the affected area. Slightly felt outside. Generally causes zero to minimal damage. Moderate to significant damage
|10,000 to 15,000 per year
|-
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|Strong
|VII to IX
|Damage to a moderate number of well-built structures in populated areas. [[Earthquake-resistant structures]] survive with slight to moderate damage. Poorly designed structures receive moderate to severe damage. Felt in wider areas; up to hundreds of kilometers from the epicenter. Strong to violent shaking in
|100 to 150 per year
|-
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|Major
|rowspan="3"| VIII or higher
|Causes damage to most buildings, some to partially or completely collapse or receive severe damage. Well-designed structures are likely to receive damage. Felt across great distances with major damage mostly limited to 250
|10 to 20 per year
|-
|8.0–8.9
|rowspan="
|Major damage to buildings,
|One per year
|-
|9.0 and greater
|
|One per 10 to 50 years
▲|Near total destruction – severe damage or collapse to all buildings. Heavy damage and shaking extend to distant locations. Permanent changes in ground topography.
|}
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Millions of minor earthquakes occur every year worldwide, equating to hundreds every hour every day.<ref name="IRIS">{{cite web|title=How Often Do Earthquakes Occur|url=http://www.mgs.md.gov/seismic/education/no3.pdf}}</ref> On the other hand, earthquakes of magnitude ≥8.0 occur about once a year, on average.<ref name="IRIS" /> The largest recorded earthquake was the [[1960 Valdivia earthquake|Great Chilean earthquake]] of May 22, 1960, which had a magnitude of 9.5 on the [[moment magnitude scale]].<ref>{{cite web |url=https://earthquake.usgs.gov/regional/world/10_largest_world.php |title=Largest Earthquakes in the World Since 1900 |date=30 November 2012 |access-date=18 December 2013 |url-status=dead |archive-url=https://web.archive.org/web/20091007163455/http://earthquake.usgs.gov/regional/world/10_largest_world.php |archive-date=October 7, 2009 |df=mdy-all }}</ref>
Seismologist Susan Hough has suggested that a magnitude 10 quake may represent a very approximate upper limit for what the Earth's tectonic zones are capable of, which would be the result of the largest known continuous belt of faults rupturing together (along the Pacific coast of the Americas).<ref>{{cite book|last1=Silver|first1=Nate|title=The signal and the noise : the art and science of prediction|date=2013|publisher=Penguin|location=London|isbn=9780141975658}}</ref> A research at the [[Tohoku University]] in Japan found that a magnitude 10 earthquake was theoretically possible if a combined {{convert|3,000|km|mi}} of faults from the [[Japan Trench]] to the [[Kuril–Kamchatka Trench]] ruptured together and moved by {{convert|60|m|ft}} (or if a similar large-scale rupture occurred elsewhere). Such an earthquake would cause ground motions for up to an hour, with tsunamis hitting shores while the ground is still shaking, and if this kind of earthquake occurred, it would probably be a 1-in-10,000
== Development ==
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