2010 Haiti earthquake

==Geology==
[[File:2010 haiti shake map.jpg|thumb|left|USGS intensity map]]
[[File:Gonâve microplate.png|thumb|Map showing regional tectonic setting of the [[Enriquillo-Plantain Garden fault zone]]]]
[[File:2010 Haiti Quake Aftershock Damage Satellite Image.jpg|thumb|Tiny dots of white against the plant-covered landscape (red in this image) are possible landslides, a common occurrence in mountainous terrain after large earthquakes. The Enriquillo-Plantain Garden fault zone runs along the two linear valleys at the top of the image.]]
The [[Moment magnitude scale|magnitude]] 7.0&nbsp;M<sub>w</sub> earthquake occurred inland, on 12 January 2010 at 16:53 (UTC−05:00), approximately {{convert|25|km|mi|abbr=on}} WSW from Port-au-Prince at a depth of {{convert|13|km|mi|abbr=on}}<ref name="USGS_Haiti"/> on [[Thrust fault#Blind thrust faults|blind thrust faults]] associated with the [[Enriquillo-Plantain Garden fault zone|Enriquillo-Plantain Garden fault system]]<ref name="USGSHaiti2" /> and lasted less than 30 seconds.
<ref>{{cite web |url=https://www.independent.co.uk/news/world/americas/earthquake-in-haiti-gone-in-30-seconds-1870284.html |title=Earthquake in Haiti: Gone in 30 seconds |last=Randall |first=David |date=17 January 2010 |website=The Independent |access-date=22 August 2019 |archive-date=22 August 2019 |archive-url=https://web.archive.org/web/20190822190507/https://www.independent.co.uk/news/world/americas/earthquake-in-haiti-gone-in-30-seconds-1870284.html |url-status=live }}</ref>
There is no evidence of surface rupture; based on seismological, geological and ground deformation data, it is also thought that the earthquake did not involve significant lateral slip on the main Enriquillo fault.<ref name="Hayes">{{cite journal|last1=Hayes|first1=G.P.|last2=Briggs|first2=R.W.|year=2010|title=Complex rupture during the 12 January 2010 Haiti earthquake|journal=Nature Geoscience|doi=10.1038/ngeo977|volume=3|issue=11|pages=800–805|bibcode=2010NatGe...3..800H|last3=Sladen|first3=A.|last4=Fielding|first4=E. J.|last5=Prentice|first5=C.|last6=Hudnut|first6=K.|last7=Mann|first7=P.|last8=Taylor|first8=F. W.|last9=Crone|first9=A. J.|last10=Gold|first10=R.|last11=Ito|first11=T.|last12=Simons|first12=M.|url=https://authors.library.caltech.edu/21200/2/ngeo977-s1.pdf|access-date=6 July 2019|archive-date=2 December 2017|archive-url=https://web.archive.org/web/20171202124109/https://authors.library.caltech.edu/21200/2/ngeo977-s1.pdf|url-status=live}}</ref> Strong shaking associated with intensity IX on the [[Modified Mercalli intensity scale|Modified Mercalli scale]] (MM) was recorded in Port-au-Prince and its suburbs. It was also felt in several surrounding countries and regions, including Cuba (MM III in [[Guantánamo, Cuba|Guantánamo]]), Jamaica (MM II in [[Kingston, Jamaica|Kingston]]), Venezuela (MM II in [[Caracas]]), Puerto Rico (MM II–III in [[San Juan, Puerto Rico|San Juan]]), and the bordering Dominican Republic (MM III in [[Santo Domingo, Dominican Republic|Santo Domingo]]).<ref name=pager2010rja6 /><ref name="USGSHaiti3" /> According to estimates from the [[United States Geological Survey|U.S. Geological Survey]], approximately 3.5&nbsp;million people lived in the area that experienced shaking intensity of MM VII to X,<ref name=pager2010rja6/> a range that can cause moderate to very heavy damage even to earthquake-resistant structures. Shaking damage was more severe than for other quakes of similar magnitude due to the quake's shallow depth.<ref>{{cite news
 |last=Bachelet 
 |first=Michelle 
 |title=More than 2 million affected by earthquake, Chile's president says 
 |publisher=CNN 
 |date=27 February 2010 
 |url=http://articles.cnn.com/2010-02-27/world/chile.quake_1_magnitude-haiti-quake-chilean-president-michelle-bachelet?_s=PM:WORLD 
 |access-date=8 November 2011 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20120118025211/http://articles.cnn.com/2010-02-27/world/chile.quake_1_magnitude-haiti-quake-chilean-president-michelle-bachelet?_s=PM%3AWORLD 
 |archive-date=18 January 2012 
}}</ref><ref>[http://www.crustal.ucsb.edu/outreach/faq.php Frequently Asked Questions] {{Webarchive|url=https://web.archive.org/web/20101203020426/http://www.crustal.ucsb.edu/outreach/faq.php |date=3 December 2010 }} Institute for Crustal Studies</ref>

The quake occurred in the vicinity of the northern boundary where the [[Caribbean plate|Caribbean tectonic plate]] shifts eastwards by about {{convert|20|mm|in|abbr=on}} per year in relation to the [[North American plate]]. The [[strike-slip fault]] system in the region has two branches in Haiti, the [[Septentrional-Oriente fault zone|Septentrional-Oriente fault]] in the north and the Enriquillo-Plantain Garden fault in the south; both its location and [[focal mechanism]] suggested that the January 2010 quake was caused by a rupture of the Enriquillo-Plantain Garden fault, which had been locked for 250&nbsp;years, gathering [[stress (mechanics)|stress]].<ref name="BBC130120101" /> However, a study published in May 2010 suggested that the rupture process may have involved slip on multiple blind thrust faults with only minor, deep, lateral slip along or near the main Enriquillo–Plantain Garden fault zone, suggesting that the event only partially relieved centuries of accumulated left-lateral strain on a small part of the plate-boundary system.<ref name="Hayes"/> The rupture was roughly {{convert|65|km|mi|abbr=on}} long with mean slip of {{convert|1.8|m}}.<ref name="colorado.edu" /> Preliminary analysis of the slip distribution found amplitudes of up to about {{convert|4|m|abbr=on}} using [[ground motion]] records from all over the world.<ref name="USGSHaiti4" /><ref name="nagoya" />

A 2007 earthquake hazard study by C. DeMets and M. Wiggins-Grandison noted that the Enriquillo-Plantain Garden fault zone could be at the end of its seismic cycle and concluded that a worst-case forecast would involve a 7.2&nbsp;M<sub>w</sub> earthquake, similar in size to the [[1692 Jamaica earthquake]].<ref name="DeMets" /> Paul Mann and a group including the 2006 study team presented a hazard assessment of the Enriquillo-Plantain Garden fault system to the 18th Caribbean Geologic Conference in March 2008, noting the large strain; the team recommended "high priority" historical geologic rupture studies, as the fault was fully locked and had recorded few earthquakes in the preceding 40&nbsp;years.<ref name="18cgc" /> An article published in Haiti's ''[[Le Matin (Haiti)|Le Matin]]'' newspaper in September 2008 cited comments by geologist Patrick Charles to the effect that there was a high risk of major seismic activity in Port-au-Prince.<ref name="lematinhaiti" />

===Aftershocks===
[[File:Haiti 2010 history.svg|thumb|History of the main shock and aftershocks with magnitudes larger than 4.0, data from USGS<ref name="USGS database" />]]

The U.S. Geological Survey recorded eight [[aftershock]]s in the two hours after the main earthquake, with magnitudes between 4.3 and 5.9.<ref name="USGS database"/> Within the first nine hours, 32 aftershocks of magnitude 4.2 or greater were recorded, 12 of which measured magnitude 5.0 or greater; in addition, on 24 January, the US Geological Survey reported that there had been 52 aftershocks measuring 4.5 or greater since the main quake.<ref name="USGS database"/>

On 20 January, at 06:03 local time (11:03 [[UTC]]), the strongest aftershock since the earthquake,<ref name="CNN aftershock" /> measuring magnitude 5.9&nbsp;M<sub>w</sub>, struck Haiti.<ref name="NYT aftershock" /> USGS reported its epicenter was about {{convert|56|km|mi|abbr=on}} WSW of Port-au-Prince,<ref name="USGS database"/> which would place it almost exactly under the coastal town of [[Petit-Goâve]]. A UN representative reported that the aftershock collapsed seven buildings in the town.<ref name="AP aftershock" /> According to staff of the [[International Committee of the Red Cross]], which had reached Petit-Goâve for the first time the day before the aftershock, the town was estimated to have lost 15% of its buildings, and was suffering the same shortages of supplies and medical care as the capital.<ref>[http://www.icrc.org/web/eng/siteeng0.nsf/html/haiti-earthquake-update-190110 Haiti earthquake: reaching victims outside the capital] {{Webarchive|url=https://web.archive.org/web/20210502113711/https://www.icrc.org/en |date=2 May 2021 }}, International Committee of the Red Cross, 19 January 2010</ref> Workers from the charity [[Save the Children]] reported hearing "already weakened structures collapsing" in Port-au-Prince,<ref name="CNN aftershock"/> but most sources reported no further significant damage to infrastructure in the city. Further casualties are thought to have been minimal since people had been sleeping in the open.<ref name="AP aftershock"/> There are concerns that the main earthquake could be the beginning of a new long-term sequence: "the whole region is fearful"; historical accounts, although not precise, suggest that there has been a sequence of quakes progressing westwards along the fault, starting with an earthquake in the Dominican Republic in 1751.<ref name="future" />

===Tsunami===
The [[Pacific Tsunami Warning Center]] issued a [[tsunami]] warning immediately after the initial quake,<ref name="AJC"/> but quickly cancelled it.<ref name="noaa1">{{cite web|url=http://www.prh.noaa.gov/ptwc/messages/caribe/2010/caribe.2010.01.12.233517.txt|title=Tsunami Message Number 3|publisher=NOAA|access-date=12 January 2010| archive-url= https://web.archive.org/web/20100115063820/http://www.prh.noaa.gov/ptwc/messages/caribe/2010/caribe.2010.01.12.233517.txt| archive-date= 15 January 2010 | url-status= live}}</ref> Nearly two weeks later it was reported that the beach of the small fishing town of [[Petit Paradis]] was hit by a localised tsunami shortly after the earthquake, probably as a result of an underwater landslide, and this was later confirmed by researchers.<ref name="BBCtsunami">[http://news.bbc.co.uk/1/hi/sci/tech/8536561.stm Lessons to be learned from Haiti's tsunami] {{Webarchive|url=https://web.archive.org/web/20200804095657/http://news.bbc.co.uk/1/hi/sci/tech/8536561.stm |date=4 August 2020 }} BBC News, 25 February 2010</ref> At least three people were swept out to sea by the wave and were reported dead. Witnesses told reporters that the sea first retreated and a "very big wave" followed rapidly, crashing ashore and sweeping boats and debris into the ocean.<ref name=tsunamiCNN>{{cite news|author=Rich Phillips |author2=Senior Producer |url=http://edition.cnn.com/2010/WORLD/americas/01/22/haiti.paradise.lost/ |title=In Petit Paradis, earthquake then tsunami |publisher=CNN|date=20 January 2010 |access-date=24 February 2010| archive-url= https://web.archive.org/web/20100126123240/http://edition.cnn.com/2010/WORLD/americas/01/22/haiti.paradise.lost/| archive-date= 26 January 2010 | url-status= live}}</ref> The tsunami reached heights up to {{Convert|3|m|abbr=on}}.<ref>{{Cite web|access-date=16 August 2021|title= Deadly Tsunami Hits Haiti After Quake|work=National Geographic|date= 23 February 2010|url= https://www.nationalgeographic.com/science/article/100223-haiti-earthquake-tsunamis-swarm|archive-url= https://web.archive.org/web/20210816141312/https://www.nationalgeographic.com/science/article/100223-haiti-earthquake-tsunamis-swarm|url-status= dead|archive-date= 16 August 2021}}</ref>