1975 North Atlantic earthquake

1975 North Atlantic Earthquake
Date 26 May 1975
Origin time 9:11 UTC [1]
Magnitude Mw 7.9 [1]
Depth 33 km (21 mi) [1]
Epicenter 35°58′N 17°39′W / 35.97°N 17.65°W [1]
Type Strike-slip
Tsunami 2.1 m (6 ft 11 in) [1]

The 1975 North Atlantic earthquake occurred on May 26 at 09:11 UTC. The epicenter was located in the North Atlantic, in an area between the Azores, Iberian Peninsula, and Morocco. It had a magnitude of Mw 7.9, or Ms 8.1.[2]

This was an intraplate earthquake that was located about 200 km south of the Gloria Fault, the presumed boundary between the African Plate and the Eurasia Plate. It had a right-lateral strike-slip focal mechanism and was unusually large for an oceanic strike-slip event.[3][4] Damage was reported in Madeira, which is about 250 km away.[5][6] A tsunami of 0.3 m in maximum water elevation was recorded in Lagos, Portugal and an eyewitness reported a 2 m (6 ft 7 in) wave height at Ponta Delgada in the Azores.[3]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 USGS (September 4, 2009), PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey
  2. ↑ Kanamori, H.; Abe, K. (1979). "Reevaluation of the Turn-of-the-Century Seismicity Peak" (PDF). Journal of Geophysical Research 84 (B11): 6134. doi:10.1029/JB084iB11p06131.
  3. ↑ 3.0 3.1 Kaabouben F., Brahim A.I., Toto E., Baptista M.A., Miranda J.M., Soares P. & Luis J.F. (2008). "On the focal mechanism of the 26.05.1975 North Atlantic event contribution from tsunami modeling" (PDF). Journal of Seismology 12 (4): 575–583. doi:10.1007/s10950-008-9110-6.
  4. ↑ Lynnes C.S. & Ruff L.J. (1985). "Source process and tectonic implications of the great 1975 North Atlantic earthquake" (PDF). Geophysical Journjal of the Royal Astronomical Society 82 (3): 497–510. doi:10.1111/j.1365-246X.1985.tb05148.x.
  5. ↑ USGS (October 20, 2012). "Earthquake History for May 26th". Today in Earthquake History. United States Geological Survey. Retrieved February 22, 2013.
  6. ↑ Abreu U., Tavares A.O. & Rodrigues D. "Processos de perigosidade natural no Município de Câmara de Lobos - Madeira, contributo para a gestão do risco e de emergência" (PDF) (in Portuguese). pp. 53–71. Retrieved February 22, 2013.