1761 Lisbon earthquake

Earthquake and tsunami in the Atlantic Ocean Lisbon earthquake (disambiguation) 1761 Lisbon earthquake 25 dead Yes Portugal, Madeira t yes8.5 12:05 WET 31 March 1761 North Atlantic Map of the North Atlantic Ocean with a bullseye marking the offshore epicenter of the earthquake southwest of the Iberia or northwest of Morocco 34.5 N 13.0 W inline, title yes The 1761 Lisbon earthquake struck off the coast of Portugal on 31 March 1761 at 12:05 Western European Time (WET). Estimated to be around 8.5 on the tsunami magnitude scale, the earthquake was the strongest in the region since 1755, and it was felt across many parts of western Europe. Twenty-five people were killed including several people who died from rockfalls in Madeira and collapsed homes at a village near Porto. In Lisbon, the earthquake destroyed several old homes and remaining ruins from the earlier disaster, although no one was killed. The earthquake generated a tsunami that struck the coasts of Portugal, Spain, England, Sicily, the Azores and Barbados, but did not cause damage. Tectonic setting The Azores-Gibraltar Fracture Zone (AGFZ) is an east–west trending plate boundary between the Eurasian and Nubian (African) plates between the Azores and Strait of Gibraltar. It accommodates the north-northeast–south-southwest convergence involving both plates. From west to east the plate boundary experiences right-lateral transtension (at Terceira Ridge) to right-lateral strike-slip motion (on the Gloria Fault) to oblique compression around the Gorringe Ridge and Alboran seafloor.Correia Ricardo Prada Manel Sallarès Valentí Cameselle Alejandra L. Pinheiro Luis Menezes Grevemeyer Ingo Ranero César R. Deep crustal structure and seismogenic potential of the Southwest Iberian Margin: insights from seismic and gravimetric data Geophysical Journal International 2025 242 3 ggaf246 10.1093/gji/ggaf246 free 10261/403976 free About 200 km south of the Gloria Fault, another approximately east–west trending structure also forms part of this plate boundary. This structure has been intepreted to be a reactivated ancient transform fault or an incipient boundary of a microplate.M. A. Baptista 2019 Tsunamis Along the Azores Gibraltar Plate Boundary https://link.springer.com/article/10.1007/s00024-019-02344-8 Pure and Applied Geophysics 117 4 1713–1724 10.1007/s00024-019-02344-8 2020PApGe.177.1713B 204741694 subscription The exact linearments of the AGFZ, called the Southwest Iberian Margin (SWIM), is uncertain due to multiple complex geologic features. This region is characterised by a broad zone of compression and transpression more than 200 km wide accommodating convergence at a rate of 4–5 mm per year. The tectonic convergence is accommodated by northeast–southwest trending thrust faults and west-northwest–east-southeast striking right-lateral strike-slip faults in a region south of the Gorringe Ridge and Gulf of Cádiz.The SWIM is thought to be related to narrow arc subduction beneath the Gibraltar Arc, involving a Jurassic oceanic slab.Parera-Portell J. A. Mancilla F. d. L. Morales J. Stich D. Geissler W. H. Silveira G. Imaging the Low Dip Onset of the Gibraltar Arc Subduction in the Gulf of Cádiz Using OBS Receiver Functions Geophysical Research Letters 2025 52 23 e2025GL117817 10.1029/2025GL117817 2025GeoRL..5217817P free Whether this subduction is active or not remains debated. Active faults in the SWIM poses a tsunami and seismic risk to populated regions nearby like Lisbon. The 1755 and 1969 Lisbon earthquakes involved slip on faults in the SWIM. Among these large northeast trending thrust faults are the Coral Patch, Gorringe Bank, Horseshoe and Marques Pombal faults.Wronna Martin Baptista Maria Ana Miranda Jorge Miguel 2019 Reanalysis of the 1761 transatlantic tsunami https://d-nb.info/1161036407/34 Natural Hazards and Earth System Sciences 19 2 337–352 10.5194/nhess-2018-30 free 10400.21/9946 free Earthquake The earthquake occurred on 31 March 1761 at 12:05 WET in Lisbon. While the exact epicenter location varies, the general area is in the SWIM, off the southwest coast of Portugal. Researchers from the National Geographic Institute of Spain placed the epicenter west of Cape St. Vincent.37.0 N 10.0 W type:event In 1986, Portugal's Laboratório Nacional de Engenharia Civil published its catalog and listed the epicenter further southwest.36.0 N 10.5 W type:event M. A. Baptista, J. M. Miranda, and J. F. Luis suggested an epicenter near the Ampère Seamount, southwest of the SWIM, and further from the gulf.34.5 N 13.0 W type:event They also estimated the tsunami magnitude (t) to be around 8.5 based on modelling a tsunami and comparing the simulated heights with the reported heights and wave period. Their conclusion was based on analyzing the seismic intensity distribution on the Iberian Peninsula and tsunami arrival time observations along the coasts of Portugal, Galicia, Ireland, England and the West Indies.Baptista M. Miranda J.M. Luis J. 2006 In Search of the 31 March 1761 Earthquake and Tsunami Source https://pubs.geoscienceworld.org/ssa/bssa/article-abstract/96/2/713/146815/In-Search-of-the-31-March-1761-Earthquake-and?redirectedFrom=fulltext Bulletin of the Seismological Society of America 96 2 713–721 10.1785/0120050111 2006BuSSA..96..713B 129323896 subscription Another tsunami data analysis by Martin Wronna, Maria Ana Baptista and Jorge Miguel Miranda further supported an epicenter area around the Ampère and Coral Patch seamounts. Impact Twenty-five deaths were attributed to the earthquake.Solares J. M. M. Mezcua J. Catalogo sismico de la Peninsula Iberica (880 a.C.-1990) 2002 https://www.ign.es/web/resources/docs/IGNCnig/SIS-Catalogo-hasta-1900.pdf Instituto Geografico Nacional In Lisbon, the earthquake was felt with a lower seismic intensity than the 1755 earthquake and there was no serious destruction,Cabral N. Revision of the Azorean catalogue of tsunamis Geological Society, London, Special Publications 2020 501 301–325 10.1144/SP501-2019-107 but many of the leftover building wreckage from the 1755 event was destroyed. Although there were no deaths in the city, several old homes collapsed while cracks appeared in some new homes. During the earthquake, which some witnesses described as lasting between 3 and 5 minutes, about 300 prisoners managed to escape their facility; all but 14 were subsequently captured. It was also felt strongly at Porto without damage, although in a village about 20 mi away, the collapse of 3 or 4 homes left several residents dead. Rockfalls were reported across Madeira and one church was destroyed. Four people died on the islands, including two people on a fishing boat who were killed by rockfalls.Borlase William LXV. Some account of the extraordinary agitation of the waters in Mount's-bay, and other places, on the 31st of March 1761: In a letter to the Reverend Dr. Charles Lyttelton, Dean of Exeter, from the Reverend William Borlase, M. A. F. R. S Philosophical Transactions of the Royal Society of London The Royal Society 1 January 1761 52 52 418–433 10.1098/rstl.1761.0067 free The shock was felt across all of mainland Portugal, the Azores and Madeira islands, and as far as Morocco, Madrid, Cork, Amsterdam and the Canary Islands.Galindo Inés Romero Carmen Martín-González Esther Vegas Juana Sánchez Nieves A Review on Historical Tsunamis in the Canary Islands: Implications for Tsunami Risk Reduction Geosciences 2021 11 5 222 10.3390/geosciences11050222 free 2021Geosc..11..222G 10261/414712 free It was also felt in parts of Europe without damage. In Madrid, the earthquake shook homes, causing residents to evacuate. At Cork, Ireland, shaking was only reported within an area encompassed by the city gates. At Fort Augustus, Scotland, the water level at Loch Ness rose 2 ft the first time and 30 in the second; some fishing boats were carried by the motion. This rising and falling of the lake surface continued for 45 minutes.Davison C. Great Earthquakes 1936 Thomas Murty and Co. London, United Kingdom At Fort Augustus, at about a p.m., the surface of Loch Ness rose suddenly about 2 ft. and continued to rise and fall for 45 min. According to another account from the same place, the movements began between noon and 1 p.m. and lasted half an hour, the rise in the level being nearly 30 in. Tsunami Teletsunami The tsunami observations were detailed in letters. At Lisbon, the sea fuctuated by up to 2.4 m with a 6 minute period that lasted until night, but the city was not inundated.National Geophysical Data Center / World Data Service: NCEI/WDS Global Historical Tsunami Database Runup Information https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/runup-more-info/389 NOAA National Centers for Environmental Information 10.7289/V5PN93H7 On Terceira and Faial in the Azores, the sea level dropped enough that the wharfs were left dry.National Geophysical Data Center / World Data Service: NCEI/WDS Global Historical Tsunami Database Runup Information https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/runup-more-info/9117 NOAA National Centers for Environmental Information 10.7289/V5PN93H7 The tsunami also caused sea level changes along the coast of Ayamonte, El Puerto de Santa María, Cádiz and Barcelona in Spain, but no information about their wave heights were detailed.Baptista M. A. Miranda J. M. Revision of the Portuguese catalog of tsunamis Natural Hazards and Earth System Sciences 2009 9 1 25–42 10.5194/nhess-9-25-2009 free 2009NHESS...9...25B https://nhess.copernicus.org/articles/9/25/2009/nhess-9-25-2009.pdf According to William Borlase, at around 16:30 AST on 31 August, on Barbados, the sea began to retreat from the shore and returned with a height of 4 ft. A letter by Abraham Mason described the "extraordinary motion" of the sea, where the tide flowed and receded every eight minutes for three hours. According to the NCEI/WDS Global Significant Earthquake Database, a run-up height of 1.2 m was listed.National Geophysical Data Center / World Data Service: NCEI/WDS Global Historical Tsunami Database Runup Information https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/runup-more-info/391 NOAA National Centers for Environmental Information 10.7289/V5PN93H7 At around 17:00 UTC on Mount's Bay in Cornwall, England, the tide rose 6 ft, retreating and advancing five times for one hour. On Sicily, tsunami waves were observed for 2 hours with heights of 0.6–1.2 m. See also Earth sciences Portugal List of historical earthquakes List of earthquakes in the Azores List of earthquakes in Portugal Notes References Category:1761 in Portugal Category:Earthquakes in Portugal Category:Earthquakes in Spain Category:Earthquakes in Morocco Category:18th century in Lisbon Category:1760s earthquakes Category:Tsunamis in Italy Category:1761 in Spain Category:18th-century tsunamis Category:1761 in science