2011 Lorca earthquake
Encyclopedia
The 2011 Lorca earthquake was a moderate magnitude 5.1 Mw
earthquake
that caused significant localized damage in the Region of Murcia
, Spain
. Centred at a very shallow depth of 1 km (0.6 mi) near the town of Lorca
, it occurred at 18:47 CEST (16:47 UTC
) on 11 May 2011, causing panic among locals and displacing many from their homes. The quake was preceded by a magnitude 4.4 (Mw) foreshock
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
. 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.
5.1 (Mw) main shock occurred inland on 11 May 2011 at 18:47 local time (16:47 UTC) about 2.5 km northeast of Lorca, Spain, at an extremely shallow focal depth
of 1 km (0.6 mi). Much of the southern Iberian Peninsula
— in particular the Murcia Region
— is located on a tectonic
zone of common seismic activity, where a plate boundary separating the Eurasia and African 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 major Alhama de Murcia fault, along an unusually shallow fault of between 40 to 50 km (25 to 31 mi) long. Local specialists also reported the presence of surface rupturing in the vicinity of the fault. Initial estimates from the United States Geological Survey
placed the magnitude of the quake at 5.3 (Mw); the European-Mediterranean Seismological Centre reported an intensity of magnitude 5.2 (ML
).
Due to a combination of extremely shallow depth and moderate magnitude, 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 VII 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
(MM III) and Madrid
. In total, the event released a surface energy (Me) equivalent to over 200 tonnes of TNT, or approximately 8.4×1011 joule
s.
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.
, at the request of regional government of Murcia, activated the Military Emergencies Unit, a branch of the Spanish Armed Forces
responsible for providing disaster relief. 340 members from three battalions (based at Bétera
, Torrejón de Ardoz
and Morón de la Frontera
) 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.
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
that caused significant localized damage in the Region of Murcia
Region of Murcia
The Region of Murcia is an autonomous community of Spain located in the southeast of the country, between Andalusia and Valencian Community, on the Mediterranean coast....
, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
. Centred at a very shallow depth of 1 km (0.6 mi) near the town of Lorca
Lorca
Lorca is a municipality and town in the autonomous community of Murcia in southeastern Spain, 36 miles southwest of the city of Murcia. It had a population of 92,694 in 2010, up from the 2001 census total of 77,477. Lorca is the municipality with the second-largest surface area in Spain with...
, it occurred at 18:47 CEST (16:47 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
) on 11 May 2011, causing panic among locals and displacing many from their homes. The quake was preceded by a magnitude 4.4 (Mw) foreshock
Foreshock
A foreshock is an earthquake that occurs before a larger seismic event 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 event....
at 17:05 (15:05 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
), that inflicted substantial damage to many older structures in the area, including the historical Espolón Tower of Lorca Castle
Lorca Castle
Lorca Castle 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 fortress an impregnable point in the southeast part of the Iberian Peninsula...
. Three people were killed by a falling cornice
Cornice
Cornice molding is generally any horizontal decorative molding that crowns any building or furniture element: the cornice over a door or window, for instance, or the cornice around the edge of a pedestal. A simple cornice may be formed just with a crown molding.The function of the projecting...
. 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
Albolote
Albolote is a city located in the province of Granada, Spain. According to Spain's Instituto Nacional de Estadística, the city has a total population of 15,563 as of 2005....
, Granada in 1956.
Geology
The magnitudeMoment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
5.1 (Mw) main shock occurred inland on 11 May 2011 at 18:47 local time (16:47 UTC) about 2.5 km northeast of Lorca, Spain, at an extremely shallow focal depth
Hypocenter
The hypocenter refers to the site of an earthquake or a nuclear explosion...
of 1 km (0.6 mi). Much of the southern Iberian Peninsula
Iberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
— in particular the Murcia Region
Region of Murcia
The Region of Murcia is an autonomous community of Spain located in the southeast of the country, between Andalusia and Valencian Community, on the Mediterranean coast....
— is located on a tectonic
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
zone of common seismic activity, where a plate boundary separating the Eurasia and African Plate
African Plate
The African Plate is a tectonic plate which includes the continent of Africa, as well as oceanic crust which lies between the continent and various surrounding ocean ridges.-Boundaries:...
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 major Alhama de Murcia fault, along an unusually shallow fault of between 40 to 50 km (25 to 31 mi) long. Local specialists also reported the presence of surface rupturing in the vicinity of the fault. Initial estimates from the United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
placed the magnitude of the quake at 5.3 (Mw); the European-Mediterranean Seismological Centre reported an intensity of magnitude 5.2 (ML
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
).
Due to a combination of extremely shallow depth and moderate magnitude, 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 VII on the Mercalli scale
Mercalli intensity scale
The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...
, 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
Alicante or Alacant is a city in Spain, the capital of the province of Alicante and of the comarca of Alacantí, in the south of the Valencian Community. It is also a historic Mediterranean port. The population of the city of Alicante proper was 334,418, estimated , ranking as the second-largest...
(MM III) and Madrid
Madrid
Madrid is the capital and largest city of Spain. The population of the city is roughly 3.3 million and the entire population of the Madrid metropolitan area is calculated to be 6.271 million. It is the third largest city in the European Union, after London and Berlin, and its metropolitan...
. In total, the event released a surface energy (Me) equivalent to over 200 tonnes of TNT, or approximately 8.4×1011 joule
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
s.
Foreshock
The earthquake was preceded by a magnitude 4.5 (ML) foreshockForeshock
A foreshock is an earthquake that occurs before a larger seismic event 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 event....
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 governmentSpanish Government
Spain is a constitutional monarchy whose government is defined by the Constitution of Spain. This was approved by a general referendum of the people of Spain in 1978...
, at the request of regional government of Murcia, activated the Military Emergencies Unit, a branch of the Spanish Armed Forces
Spanish Armed Forces
The Spanish Armed Forces are the military forces of the Kingdom of Spain. The Spanish Armed Forces are a modern military force charged with defending the Kingdom's integrity and sovereignty...
responsible for providing disaster relief. 340 members from three battalions (based at Bétera
Bétera
Bétera is a municipality in the comarca of Camp de Túria in the Valencian Community, Spain. With 19,491 inhabitants, it is the second most populous town in the Camp de Túria shire , in the second zone of the Valencia metropolitan area....
, Torrejón de Ardoz
Torrejón de Ardoz
Torrejón de Ardoz is a town in the urban area of Madrid, Spain that has about 110,000 inhabitants.It is a town 20 km east of Madrid on the NII highway . It is essentially a dormitory town, mostly consisting of apartments. It can be reached by bus from Av...
and Morón de la Frontera
Morón de la Frontera
Morón de la Frontera is a Spanish town in Seville province, Andalusia, 63 km South-East of Seville. It is primarily known as being home to Morón Air Base. The most remarkable monuments are the Moorish castle ruins and the main church...
) 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.