The 1816 North Atlantic earthquake occurred on 2 February somewhere between the

Azores Islands ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

and

Lisbon Lisbon (; pt, Lisboa ) is the capital and largest city of Portugal, with an estimated population of 544,851 within its administrative limits in an area of 100.05 km2. Grande Lisboa, Lisbon's urban area extends beyond the city's administr ...

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

. The estimated moment magnitude 8.3–8.9 earthquake had an epicenter offshore in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

, and was felt in Lisbon at 00:40 local time. Little is known about the quake, but it is believed to be one of the largest to have struck the Atlantic.

Tectonic setting

Between the

Strait of Gibraltar The Strait of Gibraltar ( ar, مضيق جبل طارق, Maḍīq Jabal Ṭāriq; es, Estrecho de Gibraltar, Archaic: Pillars of Hercules), also known as the Straits of Gibraltar, is a narrow strait that connects the Atlantic Ocean to the Medi ...

and

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

is where the

African African or Africans may refer to: * Anything from or pertaining to the continent of Africa: ** People who are native to Africa, descendants of natives of Africa, or individuals who trace their ancestry to indigenous inhabitants of Africa *** Ethn ...

(

Nubian Nubian may refer to: *Something of, from, or related to Nubia, a region along the Nile river in Southern Egypt and northern Sudan. *Nubian people *Nubian languages *Anglo-Nubian goat, a breed of goat * Nubian ibex * , several ships of the Britis ...

), and

Eurasian 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 ...

Plates meet along the

Azores–Gibraltar Transform Fault The Azores–Gibraltar Transform Fault (AGFZ), also called a fault zone and a fracture zone, is a major seismic zone in the Eastern Atlantic Ocean between the Azores and the Strait of Gibraltar. It is the product of the complex interaction between ...

. Near the Azores, the two plates meet the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

s at the ridge-ridge-fault

Azores Triple Junction The Azores Triple Junction (ATJ) is a geologic triple junction where the boundaries of three tectonic plates intersect: the North American Plate, the Eurasian Plate and the African Plate. This triple junction is located along the Mid-Atlantic R ...

on the

Mid-Atlantic ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Ame ...

, a 16,000-km-long

divergent boundary In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent b ...

on the seafloor of the

which separates the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

from the

. East of the Azores is the Azores–Gibraltar Transform Fault, specifically the strike-slip Gloria Fault which serves as the boundary between the Nubian and Eurasian plates. The plate boundaries are seismically active as they accommodate elastic strain caused by movements of the plates, and release the strain during large earthquakes. Two of the largest recorded earthquakes in the vicinity of the Azores were the 8.1 1941 Gloria Fault and 7.9 1975 North Atlantic earthquakes, which were associated with strike-slip faulting on the Azores–Gibraltar Transform Fault. The Azores–Gibraltar Transform Fault is also thought to be the source of the 1755 and 1761 Lisbon earthquakes which generated notable tsunamis.

Earthquake

Past estimates of the event have assigned a magnitude of between 6.7 and 7.6, with a macroseismic intensity of IV to VI at Lisbon and

Seville Seville (; es, Sevilla, ) is the capital and largest city of the Spanish autonomous community of Andalusia and the province of Seville. It is situated on the lower reaches of the River Guadalquivir, in the southwest of the Iberian Peninsula ...

. An epicenter location along the Gloria Fault is commonly plotted. Reassessment of the seismic intensity based on historical documentation suggests it was only felt V in

. The shock had a maximum intensity of VII evaluated and assigned to

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

. Based on simulating the documented seismic intensities on a computer, a moment magnitude of 8.6 ± 0.3 was obtained. The reevaluated epicenter location places it just northwest of the 1941 earthquake epicenter, near the Gloria Fault.

Impact

According to reports from the ''Gazeta de Lisboa'', the shock was felt at 00:40

local time Local time is the time observed in a specific locality. There is no canonical definition. Originally it was mean solar time, but since the introduction of time zones it is generally the time as determined by the time zone in effect, with daylight s ...

for up to a minute or a minute and a half. Many residents were driven out of their homes and some structures suffered minor damage. The shaking was described as moving in a northeast-southwest direction and was felt throughout Portugal. Two Portuguese vessels; the ''Paquete de Lisboa'' and ''Marquez de Angeja''located 600 km and 1,400 km from Lisbon respectively reported disturbance of the sea in the

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

. The quake was felt in Seville,

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

but no damage was reported. In

Ovar Ovar ( or ) is a city and a municipality in Aveiro District, Baixo Vouga Subregion in Portugal. The population in 2011 was 55,398, in an area of 147.70 km2. It had 42,582 eligible voters (2006). The municipality includes two cities: Ovar (16 ...

, six homes were destroyed, killing 12 people. An elderly lady was among those killed, caused by panic during the quake. One person also died in Lisbon due to panic. Up to six minutes of strong shaking was reported in

. The quake was felt through the island, and on nearby

Porto Santo Island Porto Santo Island () is a Portuguese island northeast of Madeira Island in the North Atlantic Ocean; it is the northernmost and easternmost island of the archipelago of Madeira, located in the Atlantic Ocean west of Europe and Africa. The muni ...

. On the Azores Islands, American historian William Hickley Prescott wrote in a letter that violent shaking continued for 3.5 minutes, seriously damaging homes and other structures. There are no reports suggesting a tsunami struck the coast. Much information and observations of the event in Lisbon is nonexistent due to the aftermath of the

Napoleonic Wars The Napoleonic Wars (1803–1815) were a series of major global conflicts pitting the French Empire and its allies, led by Napoleon I, against a fluctuating array of European states formed into various coalitions. It produced a period of Fren ...

, and the ongoing famine associated with the

Year Without a Summer The year 1816 is known as the Year Without a Summer because of severe climate abnormalities that caused average global temperatures to decrease by . Summer temperatures in Europe were the extreme weather, coldest on record between the years of 1 ...

References

{{reflist 1816 disasters in Europe 1816 disasters in North America History of the Azores Earthquakes in Portugal 1816 earthquakes Earthquakes in Spain History of Lisbon

Tectonic setting

Earthquake

Impact

See also

References