2011 Lorca earthquake
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The 2011 Lorca earthquake ( es, link=no, Terremoto de Lorca de 2011) was a moderate 5.1 earthquake that occurred 6:47 p.m. CEST (16:47 UTC) on 11 May 2011, near the town of Lorca, causing significant localized damage in the
Region of Murcia The Region of Murcia (, ; es, Región de Murcia ), is an Autonomous communities of Spain, autonomous community of Spain located in the southeastern part of the Iberian Peninsula, on the Mediterranean Sea, Mediterranean coast. The region is in ...
, Spain, and panic among locals, and displacing many from their homes. The quake was preceded by a magnitude 4.4 ()
foreshock A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full se ...
at 17:05 (15:05 UTC), that inflicted substantial damage to many older structures in the area, including the historical Espolón Tower of
Lorca Castle Castle of Lorca ( es, Castillo de Lorca) in Lorca, Murcia, Spain, is a fortress of medieval origin constructed between the 9th and 15th centuries. It consists of a series of defensive structures that, during the Middle Ages, made the town and the ...
, the Hermitage of San Clemente and the Convent of Virgen de Las Huertas. Three people were killed by a falling cornice. A total of nine deaths have been confirmed, while dozens are reported injured. The earthquake was the worst to hit the region since a 5.0 Mw tremor struck west of Albolote, Granada in 1956.


Geology

The magnitude 5.1 main shock occurred inland on 11 May 2011 at 18:47 local time (16:47 UTC) in the locality of Lorca, Spain, at a depth of . Much of the southern
Iberian Peninsula The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, def ...
– in particular the Murcia Region – is located on a
tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...
zone of common seismic activity, where a
plate boundary Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
separating the
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...
and
African Plate The African Plate is a major tectonic plate that includes much of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate ...
s is formed. However, most tremors in the region do not exceed perceptible magnitudes. The earthquake was estimated to be a direct result of strike-slip faulting near the majo
Alhama de Murcia fault
along an unusually shallow fault of between 40 and 50 km (25 to 31 mi) long. Local specialists also reported the presence of surface rupturing in the vicinity of the fault. Due to the shallow depth, the earthquake resulted in significant shaking throughout much of Murcia. In Lorca, near the epicentre of the quake, strong ground motions registered a maximum intensity of VI on the Mercalli scale, while many adjacent areas reported moderate shaking (MM V). Widespread light tremors were observed in locations up to several hundred kilometers from the epicentre, including
Alicante Alicante ( ca-valencia, Alacant) is a city and municipality in the Valencian Community, Spain. It is the capital of the province of Alicante and a historic Mediterranean port. The population of the city was 337,482 , the second-largest in t ...
(MM III) and
Madrid Madrid ( , ) is the capital and most populous city of Spain. The city has almost 3.4 million inhabitants and a Madrid metropolitan area, metropolitan area population of approximately 6.7 million. It is the Largest cities of the Europ ...
.


Foreshock

The earthquake was preceded by a magnitude 4.5 (ML)
foreshock A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full se ...
that struck very close to its epicentre at 17:05 local time (15:05 UTC). It was reported to be centred along the same fault zone, with a similar focal mechanism as the main shock. Though the tremor was relatively mild, some cracks and crumbled walls were reported, while downed power lines sparked a small fire in Lorca.


Aftershock

As of 11 May, at least eight light aftershocks were reported near the initial quake epicentres; the strongest registered a magnitude of 4.1 (ML) and occurred at 22:37 local time (20:37 UTC).


Emergency management

Shortly after the second earthquake struck, the
Spanish government gl, Goberno de España eu, Espainiako Gobernua , image = , caption = Logo of the Government of Spain , headerstyle = background-color: #efefef , label1 = Role , data1 = Executive power , label2 = Established , da ...
, at the request of regional government of Murcia, activated the
Military Emergencies Unit The Emergency Military Unit ( es, Unidad Militar de Emergencias, UME; ) is a branch of the Spanish Armed Forces responsible for providing disaster relief throughout Spain mainly, and abroad if required. It is the newest branch of the Spanish Arm ...
, a branch of the Spanish Armed Forces responsible for providing disaster relief. 340 members from three battalions (based at
Bétera Bétera () is a municipality in the ''comarca'' of Camp de Túria in the Valencian Community, Spain. With 23.647 inhabitants, it is the second most populous town in the Camp de Túria shire (INE 2018), in the second zone of the Valencia metropol ...
,
Torrejón de Ardoz Torrejón de Ardoz () is a municipality of Spain belonging to the Community of Madrid. The European Union Satellite Centre (SatCen), an agency of the European Union, is located in Torrejón de Ardoz. It is also the location of the headquarters of ...
and
Morón de la Frontera Morón de la Frontera () is a Spanish town in Province of Seville, Seville province, Andalusia, South-East of Seville. Situated in the south of the province, it is the center of the region that bears the same name and is the head of one of the 85 ...
) were dispatched to Lorca under the management of the Lieutenant Colonel of the Bétera battalion; these were later joined by army units. A field hospital was set up by the Military Emergencies Unit in the ''Plaza del Ayuntamiento'' where those injured were attended to by members of '' Protección Civil'' and the
Red Cross The International Red Cross and Red Crescent Movement is a humanitarian movement with approximately 97 million volunteers, members and staff worldwide. It was founded to protect human life and health, to ensure respect for all human beings, and ...
.


Possible causes

Several research groups investigated the cause of this earthquake. The Active Tectonics Group of the
Complutense University of Madrid The Complutense University of Madrid ( es, Universidad Complutense de Madrid; UCM, links=no, ''Universidad de Madrid'', ''Universidad Central de Madrid''; la, Universitas Complutensis Matritensis, links=no) is a public research university loc ...
in collaboration with the Instituto Andaluz de Geofísica using tectonic evidences,
InSAR Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing. This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface defo ...
analysis and seismological analysis of the rupture concluded that this earthquake was produced by the reactivation of a small section (3 km x 4 km) of the Alhama de Murcia Fault (AMF) located 3 km northeast of
Lorca, Spain Lorca () is a municipality and city in the autonomous community of the Region of Murcia in south-eastern Spain, southwest of the city of Murcia. The municipality had a population of 95,515 in 2020, up from the 2001 census total of 77,477. Lorca is ...
. These conclusions were published in the journal
Tectonophysics (journal) ''Tectonophysics, The International Journal of Geotectonics and the Geology and Physics of the Interior of the Earth'' is a weekly peer-reviewed scientific journal published by Elsevier. It was established in 1964 and covers the field of tectonophy ...
in April 2012. The great damage produced by this moderate magnitude earthquake may be explained by the southwestward directivity of a shallow rupture that induced high acceleration values in Lorca village. From the tectonic point of view this earthquake can be considered as an ordinary event coherent with the tectonic evolution and mechanical characteristics of the Alhama de Murcia Fault. In fact, similar earthquakes occurred in Lorca in the 16th and 17th centuries. Several research projects conducted during the last 25 years on this fault recognized the occurrence of much larger earthquakes ( > 6.0) during the last 10,000 years. Other scientific research has suggested that the earthquake was caused by human activity. A team led by Dr Pablo Gonzalez of the
University of Western Ontario The University of Western Ontario (UWO), also known as Western University or Western, is a public research university in London, Ontario, Canada. The main campus is located on of land, surrounded by residential neighbourhoods and the Thames R ...
in Canada reported in the journal
Nature Geoscience ''Nature Geoscience'' is a monthly peer-reviewed scientific journal published by the Nature Publishing Group. The Chief Editor is Tamara Goldin, who took over from Heike Langenberg in February 2020. It was established in January 2008. Scope The ...
in October 2012 that the pattern of earth movement was consistent with changes in stresses caused by the removal of water from underground reservoirs.


See also

* List of earthquakes in 2011 *
List of earthquakes in Spain This is a list of notable earthquakes that had epicentres in Spain, or significantly affected the country. Geology Spain lies on the Eurasian Plate just to the north of its boundary with the African Plate. The southernmost part of Spain is the zo ...


References


External links

* {{DEFAULTSORT:Lorca Earthquake, 2011 2011 in Murcia (region) 2011 earthquakes Earthquakes in Spain 2011 earthquake May 2011 events in Europe