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Modified Mercalli intensity scale
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=== Correlation with magnitude === {| cellspacing="3" cellpadding="3" style="width:20%; border:1px aqua ; background:#eee; margin:0 auto 0 auto; float:right;" |- ! style="text-align:left" |Magnitude | '''Typical Maximum Modified Mercalli Intensity''' |- ! style="text-align:left" |1.0–3.0 | '''I''' |- ! style="text-align:left" |3.0–3.9 | '''II–III''' |- ! style="text-align:left" |4.0–4.9 | '''IV–V''' |- ! style="text-align:left" |5.0–5.9 | '''VI–VII''' |- ! style="text-align:left" |6.0–6.9 | '''VII–IX''' |- ! style="text-align:left" |7.0 and higher | '''VIII or higher''' |- | colspan="2" style="text-align: center;" | <small><span class="plainlinks">[https://web.archive.org/web/20110623113247/http://earthquake.usgs.gov/learn/topics/mag_vs_int.php Magnitude/intensity comparison, USGS]</span></small> |} Magnitude and intensity, while related, are very different concepts. Magnitude is a function of the energy liberated by an earthquake, while intensity is the degree of shaking experienced at a point on the surface, and varies from some maximum intensity at or near the epicentre, out to zero at distance. It depends upon many factors, including the depth of the [[Hypocenter|hypocentre]], terrain, distance from the epicentre, whether the underlying strata there amplify surface shaking, and any directionality due to the earthquake mechanism. For example, a magnitude 7.0 quake in [[Salta]], Argentina, in 2011, that was 576.8 km deep, had a maximum felt intensity of V,<ref>{{Cite web |publisher=United States Geological Survey |title=M 7.0 – 26 km NNE of El Hoyo, Argentina – Impact |url=https://earthquake.usgs.gov/earthquakes/eventpage/usp000hsdc/impact |website=ANSS Comprehensive Earthquake Catalog}}</ref> while a magnitude 2.2 event in [[Barrow-in-Furness]], England, in 1865, about 1 km deep, had a maximum felt intensity of VIII.<ref name="BGS_online_EQ_database">{{Cite web |url=http://www.quakes.bgs.ac.uk/historical/query_eq/ |title=UK Historical Earthquake Database |publisher=British Geological Survey |access-date=2018-03-15}}</ref> The small table is a rough guide to the degrees of the MMI scale.<ref name="comparison" /><ref name="abag">{{cite web|title=Modified Mercalli Intensity Scale|url=http://resilience.abag.ca.gov/shaking/mmi/|publisher=[[Association of Bay Area Governments]]|access-date=2017-09-02|archive-date=2023-03-26|archive-url=https://web.archive.org/web/20230326023832/http://resilience.abag.ca.gov/shaking/mmi/|url-status=dead}}</ref> The colours and descriptive names shown here differ from those used on certain shake maps in other articles.
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