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The earthquake is interpreted to have resulted from movement on a southeast-dipping reverse fault. Analysis of seismigrams of the earthquake revealed two subevents comprised the rupture process. The first subevent, a pure thrust-faulting mechanism, occurred during the first 15 seconds of the rupture.
344:
accompanied by slow convergence (4 mm/yr). Linear bathymetric features within this zone, such as the SWâNE trending
Gorringe Bank, are thought to be a result of reverse faulting. Investigations using
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At magnitude 7.8, the earthquake was considered very powerful. The resulting damage killed 13 people (11 in
Morocco and 2 in Portugal). Damage to local buildings was "moderate", according to the
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Zitellini, N.; GrĂĄcia E.; Matias L.; Terrinha P.; Abreu M.A.; DeAlteris G.; Henriet J.P.; DaĂąobeitia J.J.; Masson D.G.; Mulder T.; Ramella R.; Somoza L. & Diez S. (2009).
558:"Simulations of strong ground motion in SW Iberia for the 1969 February 28 (Ms = 8.0) and the 1755 November 1 (M ~ 8.5) earthquakes â II. Strong ground motion simulations"
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Twenty seconds after the rupture onset, a larger subevent occurred with a strike-slip mechanism at shallower depths, reaching the seafloor.
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bathymetry have revealed additional SWâNE trending reverse faults and fold axes and a set of WNWâESE trending lineaments, interpreted as
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Grimison, Nina L.; Chen, Wang-Ping (1988). "Source mechanisms of four recent earthquakes along the AzoresâGibraltar plate boundary".
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353:. The earthquake was located within the Horseshoe Abyssal Plain, where active reverse faulting has been imaged on
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Fukao, Y. (1973). "Thrust faulting at a lithospheric plate boundary the
Portugal earthquake of 1969".
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of the earthquake lies within a diffuse zone of seismicity known as the
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ISC-GEM Global
Instrumental Earthquake Catalogue (1900â2009)
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struck western
Portugal and Morocco on 28 February at 02:40
492:"Sismo 1969. O mar borbulhou e o paĂs saiu Ă rua em pijama"
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indicates earthquake resulting in at least 30 deaths
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294:of 7.8 and the maximum felt intensity was VII (
868:indicates the deadliest earthquake of the year
47:Location off the coast of Morocco and Portugal
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423:"Comments for the Significant Earthquake"
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340:in style, with dextral (right lateral)
328:, which marks the boundary between the
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652:"Earthquake History for February 28th"
490:Henriques, Graça (28 February 2019).
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618:Earth and Planetary Science Letters
523:Earth and Planetary Science Letters
73:1969 Portugal earthquake (Portugal)
724:International Seismological Centre
692:10.1111/j.1365-246X.1988.tb00003.x
478:International Seismological Centre
241:1.14 m (3 ft 9 in)
16:Earthquake in Portugal and Morocco
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679:Geophysical Journal International
566:Geophysical Journal International
588:10.1111/j.1365-246X.2007.03571.x
316:Geology of the Iberian Peninsula
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656:United States Geological Survey
458:United States Geological Survey
393:List of earthquakes in Portugal
367:United States Geological Survey
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398:List of earthquakes in Morocco
290:, the earthquake registered a
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695:(inactive 18 September 2024).
326:AzoresâGibraltar seismic belt
543:10.1016/0012-821X(73)90058-7
453:PAGER-CAT Earthquake Catalog
388:List of earthquakes in 1969
164:22.0 km (13.7 mi)
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638:10.1016/j.epsl.2008.12.005
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286:. Originating west of the
125:28 February 1969
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450:USGS (4 September 2009),
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403:1761 Portugal earthquake
300:Mercalli intensity scale
280:1969 Portugal earthquake
22:1969 Portugal earthquake
1221:Earthquakes in Portugal
630:2009E&PSL.280...13Z
535:1973E&PSL..18..205F
1231:Earthquakes in Morocco
304:1755 Lisbon earthquake
261:Feb 28 at 04:25:35 UTC
906:Earthquakes in Africa
456:, Version 2008_06.1,
361:Damage and casualties
1139:2005 Lake Tanganyika
1050:1969 Sharm El Sheikh
76:Show map of Portugal
1104:1999 AĂŻn TĂŠmouchent
925:1624 Fez earthquake
772:Earthquakes in 1969
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288:Strait of Gibraltar
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91:1969-02-28 02:40:32
50:Show map of Morocco
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1098:1995 Gulf of Aqaba
732:authoritative data
658:. 18 December 2009
496:Diario de Noticias
355:seismic reflection
351:strike-slip faults
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845:(5.6, 5.7, Oct 1)
494:(in Portuguese).
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190:36.017°N 10.950°W
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1074:1989 Chenoua
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1032:1969 Tulbagh
1002:1921 Massawa
983:20th century
949:1761 Morocco
931:1716 Algiers
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728:bibliography
701:cite journal
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1175:2014 Orkney
1121:2002 Kalehe
1068:1989 Malawi
1062:1983 Guinea
1020:1960 Agadir
996:1915 Asmara
990:1913 Asmara
943:1755 Meknes
662:28 February
594:13 February
342:strike-slip
296:Very strong
248:Aftershocks
228:Very strong
193: /
99: event
1215:Categories
1169:2011 Nabro
1086:1992 Cairo
1008:1954 Chlef
961:1825 Blida
937:1754 Cairo
912:Historical
849:Banja Luka
843:Santa Rosa
409:References
314:See also:
272:80 injured
270:13 killed
267:Casualties
181:10°57â˛00âłW
178:36°01â˛01âłN
129:1969-02-28
88: time
1038:1966 Toro
1026:1963 Marj
975:(7.7â8.2)
955:1790 Oran
828:Yangjiang
428:27 August
322:epicenter
298:) on the
292:magnitude
226:MMI VII (
220:intensity
212:, Morocco
169:Epicenter
145:Magnitude
801:AlaĹehir
795:Portugal
786:Sulawesi
501:10 March
382:See also
332:and the
243:3 runups
210:Portugal
140:02:40:32
921:(⼠7.0)
837:Tulbagh
730:and/or
626:Bibcode
575:Bibcode
531:Bibcode
238:Tsunami
127: (
726:has a
421:NGDC.
357:data.
116:ComCat
103:812637
1201:(6.8)
1195:(6.5)
1189:(5.9)
1183:(5.8)
1177:(5.5)
1171:(5.7)
1165:(5.3)
1159:(6.0)
1153:(5.9)
1147:(7.0)
1141:(6.8)
1135:(6.3)
1129:(6.8)
1123:(6.2)
1106:(5.6)
1100:(7.3)
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1076:(5.9)
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1040:(6.8)
1034:(6.3)
1028:(5.6)
1022:(5.8)
1016:(6.3)
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1004:(6.1)
963:(7.0)
957:(6.0)
951:(8.5)
945:(7.0)
939:(6.6)
933:(7.0)
927:(6.0)
822:Bohai
810:Sardo
614:(PDF)
561:(PDF)
161:Depth
109:USGS-
998:(VI)
992:(VI)
969:(IX)
722:The
707:link
664:2010
596:2011
503:2022
430:2010
320:The
278:The
252:6.3
218:Max.
148:7.8
111:ANSS
687:doi
634:doi
622:280
583:doi
571:171
539:doi
284:UTC
97:ISC
86:UTC
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832:â âĄ
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699:{{
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257:w
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