1968 Aegean Sea earthquake

Earthquake affecting Greece and Turkey
39°22′05″N 24°57′25″E / 39.368°N 24.957°E / 39.368; 24.957 Central Aegean SeaFaultNorth Anatolian Fault[10][13]TypeStrike-slipAreas affectedTurkey, GreeceTotal damage$0.6 million USD[14]Max. intensityMMI IX (Violent)[10]Peak acceleration0.17 g[10]ForeshocksML  3.2 1 minute prior[10] AftershocksOver 2800, the largest of which was ML  5.3-5.6[10][12] Casualties20 dead, 39 injured[10]

The 1968 Aegean Sea earthquake was a Mw 7.0 earthquake that occurred in the early morning hours of February 20, 1968 local time about 57.1 km (35.5 mi) away from Myrina, Greece. This earthquake occurred between mainland Greece and Turkey, meaning both countries were impacted. 20 people died, and 39 people were injured to various degrees. It was the deadliest Greek earthquake since the 1956 Amorgos earthquake.

Tectonic setting

In the central Aegean Sea, the Aegean Sea Plate has a strike-slip boundary with the Anatolian Plate which accommodates deformation from seismic stresses.[15] A large strike slip fault, the North Anatolian Fault in Turkey, developed to more easily allow faulting in the area.[15] A large strand of the North Anatolian Fault branches southwest and traces near the north coast of the Gulf of Edremit.[12][5] This segment of the fault begins northeast of the gulf, at Lake Manyas. The segment enters the Aegean Sea near the town of Babakale, Ayvacık.

Earthquake

The Mw 7.0 earthquake struck nearest to the island of Lemnos, Greece in the middle of the night of February 20. The source parameters of the earthquake indicate right-lateral strike slip faulting along the North Anatolian fault or a similar right lateral extension at the shallow depth of 6.9 km (4.3 mi).[10][16] The earthquake had faulting dimensions of 60–75 km (37–47 mi) by 10–15 km (6.2–9.3 mi) with an average slip of 1.8–3.2 m (5 ft 11 in – 10 ft 6 in).[3][16] Surface rupturing was reported on Agios Efstratios island.[2] There were many recorded aftershocks (over 2800), with the largest being ML 5.3–5.6.[12] The earthquake was reportedly felt from as far away as Ankara, Turkey, and Sofia, Bulgaria.[10] A Ms  6.5 earthquake in 1967 put stress on the fault that ruptured during this event, and the rupture from this earthquake put strain on two faults: one that ruptured in a Ms  7.2 earthquake in 1981, and another fault that hosted a Ms  6.9 event in 1982.[16] This earthquake also released stress on nearby faults. Both the fault that ruptured in a Ms  6.4 event in late December 1981 and one that ruptured in a Ms  6.9 event in 1983 had reduced strain after this earthquake struck.[16]

Tsunami

Despite being a strike slip event, a type of faulting that does not typically favor tsunamigenesis, a 1.2 m (3 ft 11 in) tsunami wave was recorded at the port of Myrina.[11][10] The cause may have been slumping on western St. Eustratios island.[10]

Damage

The earthquake killed 20 people, severely injured a further 18, while 21 had light injuries.[10] 175 houses collapsed in the earthquake, while another 397 were damaged so severely they could not be repaired.[10] 1951-2348 buildings had some structural damage such as cracks.[10][17] Some homes on Lemnos were also damaged by the shock.[14] The shaking was compounded with poor building quality and local conditions allowing for shaking amplification.[10] 3600 people became homeless as a result of this earthquake, and a total of 7618 people were affected.[18] As the island of Agios Efstratios is small and rather limited in resources, the island's authorities were unable to provide all of the relief from the disaster effects that were needed in the immediate aftermath of the earthquake.[17] Monetary damage was 600 thousand 1968 dollars, and when adjusted for inflation in 2000, damage from this earthquake amount to 4.674 million dollars.[18]

See also

Notes

  1. ^ Mw 7.0,[1] Mw  7.2[2]
    Ms 7.0,[3][4] Ms  7.1,[5] Ms  7.2,[4] Ms  7.3,[6][7] Ms  7.4,[8] Ms  7.5[9]
    mb 6.0,[4] mb  7.1[9]
    Mfa 7.4[10]
    M 7.1[11][12]

References

  1. ^ a b "M 7.0 - 57 km S of Mýrina, Greece". USGS. Retrieved 23 July 2022.
  2. ^ a b Kiratzi & Svigkas 2013.
  3. ^ a b North 1977.
  4. ^ a b c Taymaz, Jackson & McKenzie 1991.
  5. ^ a b Papazachos, Kiratzi & Papadimitriou 1991.
  6. ^ Jackson & McKenzie 1988.
  7. ^ Ambraseys & Jackson 1998.
  8. ^ a b International Seismological Centre. ISC-GEM Global Instrumental Earthquake Catalogue. Thatcham, United Kingdom. [Event 826342].
  9. ^ a b Abe 1981.
  10. ^ a b c d e f g h i j k l m n o Drakopoulos & Ekonomides 1972.
  11. ^ a b "February 19, 1968". O.A.S.P. Retrieved 24 July 2022.
  12. ^ a b c d Pavlides & Tranos 1991.
  13. ^ Onat 2022.
  14. ^ a b "NGDC". NGDC. Retrieved 24 July 2022.
  15. ^ a b McNeill et al. 2004.
  16. ^ a b c d Nalbant, Hubert & King 1998.
  17. ^ a b Mavroulis et al. 2022.
  18. ^ a b "EM-DAT, the International Disaster Database". EMDAT. Retrieved 15 November 2022.

Sources

  • Abe, Katsuyuki (October 1981). "Magnitudes of large shallow earthquakes from 1904 to 1980". Physics of the Earth and Planetary Interiors. 27 (1): 72–92. Bibcode:1981PEPI...27...72A. doi:10.1016/0031-9201(81)90088-1. Retrieved 15 November 2022.
  • Ambraseys, N. N.; Jackson, J. A. (1 May 1998). "Faulting associated with historical and recent earthquakes in the Eastern Mediterranean region". Geophysical Journal International. 133 (2): 390–406. Bibcode:1998GeoJI.133..390A. doi:10.1046/j.1365-246X.1998.00508.x. Retrieved 15 November 2022.
  • Drakopoulos, J. C.; Ekonomides, A. C. (December 1972). "Aftershocks of February 19, 1968 earthquake in Northern Aegean Sea and related problems". Pure and Applied Geophysics. 95 (1): 100–115. Bibcode:1972PApGe..95..100D. doi:10.1007/BF00878858. S2CID 128422196. Retrieved 24 July 2022.
  • Jackson, James; McKenzie, Dan (1 April 1988). "The relationship between plate motions and seismic moment tensors, and the rates of active deformation in the Mediterranean and Middle East". Geophysical Journal International. 93 (1): 45–73. Bibcode:1988GeoJI..93...45J. doi:10.1111/j.1365-246X.1988.tb01387.x. S2CID 129204895.
  • Kiratzi, Anastasia A.; Svigkas, Nikos (26 November 2013). "A study of the 8 January 2013 Mw5.8 earthquake sequence (Lemnos Island, East Aegean Sea)". Tectonophysics. 608: 452–460. Bibcode:2013Tectp.608..452K. doi:10.1016/j.tecto.2013.09.002. Retrieved 15 November 2022.

Mavroulis, S.; Ilgac, M.; Tunçağ, M.; Lekkas, E.; Püskülcü, S.; Kourou, A.; Sextos, A.; Mavroulis, M.; Can, G.; Thoma, T.; Manousaki, M.; Karveleas, N. (12 January 2022). "Emergency response, intervention, and societal recovery in Greece and Turkey after the 30th October 2020, MW = 7.0, Samos (Aegean Sea) earthquake". Bulletin of Earthquake Engineering. 20 (14): 7933–7955. Bibcode:2022BuEE...20.7933M. doi:10.1007/s10518-022-01317-y. PMC 8753335. PMID 35210982. S2CID 245856772.

  • McNeill, L. C.; Mille, A.; Minshull, T. A.; Bull, J. M.; Kenyon, N. H.; Ivanov, M. (23 April 2004). "Extension of the North Anatolian Fault into the North Aegean Trough: Evidence for transtension, strain partitioning, and analogues for Sea of Marmara basin models". Tectonics. 23 (2). Bibcode:2004Tecto..23.2016M. doi:10.1029/2002TC001490. S2CID 129344593.
  • Nalbant, Süleyman S.; Hubert, Aurélia; King, Geoffrey C. P. (10 October 1998). "Stress coupling between earthquakes in northwest Turkey and the north Aegean Sea". Journal of Geophysical Research. 103 (B10): 24469–24486. Bibcode:1998JGR...10324469N. doi:10.1029/98JB01491.
  • North, Robert G. (1 February 1977). "Seismic moment, source dimensions, and stresses associated with earthquakes in the Mediterranean and Middle East". Geophysical Journal International. 48 (2): 137–161. Bibcode:1977GeoJ...48..137N. doi:10.1111/j.1365-246X.1977.tb01293.x.
  • Onat, O. (May 2022). "Field reconnaissance and structural assessment of the October 30, 2020, Samos, Aegean Sea earthquake: an example of severe damage due to the basin effect". Natural Hazards. 112 (112): 75–117. Bibcode:2022NatHa.112...75O. doi:10.1007/s11069-021-05173-y. PMC 8782695. PMID 35095193.
  • Papazachos, B.; Kiratzi, A.; Papadimitriou, E. (December 1991). "Regional focal mechanisms for earthquakes in the Aegean area". Pure and Applied Geophysics. 136 (4): 405–420. Bibcode:1991PApGe.136..405P. doi:10.1007/BF00878578. S2CID 140202748. Retrieved 15 November 2022.
  • Pavlides, S. B.; Tranos, M. D. (1991). "Structural characteristics of two strong earthquakes in the North Aegean: ierissos (1932) and Agios Efstratios (1968)". Journal of Structural Geology. 13 (2): 205–213. Bibcode:1991JSG....13..205P. doi:10.1016/0191-8141(91)90067-S.
  • Taymaz, Tuncay; Jackson, James; McKenzie, Dan (1 August 1991). "Active tectonics of the north and central Aegean Sea". Geophysical Journal International. 106 (2): 433–490. Bibcode:1991GeoJI.106..433T. doi:10.1111/j.1365-246X.1991.tb03906.x. S2CID 130112976.
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† indicates earthquake resulting in at least 30 deaths
‡ indicates the deadliest earthquake of the year