1766 Istanbul earthquake

The 1766 Istanbul earthquake was a strong earthquake with epicenter in the eastern part of the Sea of Marmara, in the Çınarcık Basin (or near the Princes' Islands, north of the basin)[2] which occurred in the early hours of Thursday morning, 22 May 1766.[1] The earthquake had an estimated magnitude of 7.1 on the surface wave magnitude scale,[2] and caused effects in a vast area extending from Izmit to Rodosto (now Tekirdağ).[3] In this area, the earthquake was followed by a tsunami which caused significant damage. The earthquake of 1766 was the last major earthquake to rock Constantinople (now known in English under its Turkish name, Istanbul) because of a rupture of the North Anatolian Fault in the Marmara region.[4][5]

1766 Istanbul earthquake
Drawing showing earthquake damage.
A tower near the Hücum Kapısı ("The assault gate") belonging to the walls of Constantinople damaged by the earthquake in an engraving by W. H. Bartlett (ante 1838).
1766 Istanbul earthquake is located in Marmara
1766 Istanbul earthquake
Location of epicenter in the Marmara region of Turkey
Local date22 May 1766 (1766-05-22)
Local time05:10
Magnitude7.1 Ms
Epicenter40°48′N 29°00′E / 40.8°N 29°E / 40.8; 29[1]
FaultNorth Anatolian Fault
Areas affectedEyalet of Constantinople, Ottoman Empire
Tsunamiflooded Bosphorus shores, Galata, Mudanya, Princes' Islands

Geology edit

The Sea of Marmara is a pull-apart basin formed at a releasing bend in the North Anatolian Fault ("NAF"), a right-lateral strike-slip fault.[6] East of the Sea of Marmara the NAF splits in three major branches; while the sinuous southern branch goes inland in direction SW up to Ayvacık, where it reaches the Aegean Sea near the southern mouth of the Dardanelles, the other two major branches (northern and central) of the NAF, being under the sea of Marmara about 100 km (62 mi) apart, form the Marmara pull-apart basin, meeting again under the NE Aegean.[6] This local zone of extension occurs where this transform boundary between the Anatolian Plate and the Eurasian Plate steps northwards to the west of Izmit from the Izmit Fault to the Ganos Fault. Inside the Sea of Marmara there is a smaller pull-apart basin, named the North Marmara fault System ("NMFS"), which connect the three submarine basins (from W to E: Tekirdağ, Central and Çınarcık) with the Izmit and Ganos Fault (both inland).[6] Near Istanbul the northern side of the NMFS pull-apart coincides with the northern branch of the NAF and is a single main fault segment with a sharp bend.[6] To the west, the fault trends W-E and is pure strike-slip in type. To the east, the fault is NW-SE trending and shows evidence of both normal and strike-slip motion.[6]

In 1766, the rupture of the fault happened either under the Princes' Islands[5] or, more probably, under the Çınarcık Basin, since a more central break could not have caused the great tsunami that struck Istanbul and the Gulf of Izmit, although this had been produced by a submarine landslide.[7] The 1766 event has been the last one caused by a rupture of the NAF in the Marmara region;[4] successive large events which caused extensive damage in Istanbul, like the earthquake of 10 July 1894 (with epicenter in the gulf of Izmit) and that of 9 August 1912 (with epicenter NW of Marmara Island), have to be considered isolated events caused by the non uniform stress relief during the 18th century earthquake sequence, to which the 1766 event belongs.[4] Since the second last major event with an epicenter in the Istanbul region occurred in 1509, a recurrence interval of 200–250 years has been hypothesized.[8]

Characteristics edit

The earthquake began half an hour after sunrise, at 5:10 a.m. on May 22, 1766, which was the third day of the Kurban Bairam.[9] The first shock, accompanied by a loud roar, lasted two minutes:[9] it was followed by a less intense shock lasting four minutes, and aftershocks continued for eight minutes.[9] In the following weeks there were also several aftershocks, and the duration of the whole sequence amounted to one year.[10] Mathematical models of this event using Coulomb stress transfer are consistent with a fault rupture whose length ranges from 70 to 120 km (43 to 75 mi).[4]

The earthquake was felt as far away as Aydın, Thessaloniki, on Mount Athos, Aytos in eastern Bulgaria and along the west coast of the Black Sea.[10] This earthquake was compared to the catastrophic one in Lisbon, which occurred 11 years earlier.[11]

Damage edit

The Fatih mosque and its complex (here in 1559 in a drawing of Melchior Lorck) were destroyed in 1766

The estimated area of significant damage (greater than the MCS VII grade (Very Strong)) extends from Bursa to Küçükçekmece,[12] but destruction occurred from Tekirdağ and Gelibolu to the west, Izmit to the east and Edirne to the north.[13][10] The settlements on the Gulf of Mudanya also suffered damage,[7] while Galata and Büyükçekmece were severely damaged. In Constantinople the intensity of the earthquake was estimated between grade VII [14] and VIII-IX;[12] many houses and public buildings collapsed.[10] Furthermore, part of the underground water distribution system was destroyed;[10] the Ayvad dam, on the upper Kâğıthane, was damaged, and in Istanbul the vault of an underground cistern subsided.[10]

In Istanbul, most of the mosques and churches were damaged, as was the Topkapı Palace: the sultan had to live in temporary housing until his home was restored.[15] The panicking populace was unable to go back home, and people sheltered themselves in tents pitched in wide and open spaces.[16] Among the imperial mosques, the dome of that of Bayezid was damaged,[17] while the minaret and the main dome of the mosque of Mihrimah collapsed.[18] The Süleymaniye Mosque was also damaged,[19] while the Fatih mosque suffered the collapse of the minarets, the main dome and several secondary domes,[20] and 100 students in the Koran school of the Külliye died; so the complex had to be rebuilt.[15] The Kariye Mosque was also seriously damaged,[21] but the mosque of Ayasofya survived instead almost unharmed.[22][23]

The castle of Yedikule,[24] Eğrikapı, Edirnekapı and the city walls were also damaged, while there was damage to Galata and Pera and to the Grand Bazaar.[25][26] At Çatalca and in the surrounding villages all the masonry buildings collapsed.[10] Since the earthquake struck the eastern part of the Sea of Marmara, serious damage was also recorded on the southern shore, from Mudanya to Karamürsel,[10] and the tsunami waves made the ports unusable. The highest level of the tsunami was observed in the Bosphorus region;[4] the flood was also strong on the shores of Galata and Mudanya, while some small islands in the Marmara Sea were partially submerged.

Casualties edit

The number of deaths was estimated at 4,000,[4][10] of which 880 were in Istanbul.[4]

August earthquake edit

In August of the same year, a magnitude 7.4 earthquake struck the Dardanelles region. On that occasion the damage in Istanbul was slight.[13]

References edit

  1. ^ a b N. N. Ambraseys; J. A. Jackson (June 2000). "Seismicity of the Sea of Marmara (Turkey) since 1500". Geophysical Journal International. 141 (3): F1. Bibcode:2000GeoJI.141F...1A. doi:10.1046/j.1365-246x.2000.00137.x.
  2. ^ a b N.N. Ambraseys (December 2001). "The Earthquake of 1509 in the Sea of Marmara, Turkey, Revisited". Bulletin of the Seismological Society of America. 91 (6): 1397–1416. Bibcode:2001BuSSA..91.1397A. doi:10.1785/0120000305.
  3. ^ Erhan Afyioncu (20 August 2017). "Istanbul'un son buyuk depremi". Sabah (in Turkish). Retrieved 27 October 2019.
  4. ^ a b c d e f g Nicolas Pondard; Rolando Armijo; Geoffrey C. P. King; Bertrand Meyer; Frederic Flerit (2007). "Fault interactions in the Sea of Marmara pull-apart (North Anatolian Fault): earthquake clustering and propagating earthquake sequences" (PDF). Geophys. J. Int. 171 (3): 1185–1197. Bibcode:2007GeoJI.171.1185P. doi:10.1111/j.1365-246X.2007.03580.x. Retrieved 7 November 2019.
  5. ^ a b Marco Bohnhoff; Patricia Martínez-Garzón; Fatih Bulut; Eva Stierle; Yehuda Ben-Zion (2 April 2016). "Maximum earthquake magnitudes along different sections of the North Anatolian fault zone". Tectonophysics. 674: 147–165. Bibcode:2016Tectp.674..147B. doi:10.1016/j.tecto.2016.02.028.
  6. ^ a b c d e Armijo, R.; Meyer B.; Navarro S.; King G. & Narka A. (2002). "Asymmetric slip partitioning in the Sea of Marmara pull-apart: a clue to propagation processes of the North Anatolian Fault?" (PDF). Terra Nova. 14 (2): 80–86. Bibcode:2002TeNov..14...80A. CiteSeerX doi:10.1046/j.1365-3121.2002.00397.x. S2CID 49553634. Retrieved 7 November 2019.
  7. ^ a b Helene Hebert; Francois Schindele; Yildiz Altinok; Bedri Alpar; Cem Gazioglu (2005). "Tsunami hazard in the Marmara Sea (Turkey): a numerical approach to discuss active faulting and impact on the Istanbul coastal areas" (PDF). Marine Geology. 215 (1–2): 23–43. Bibcode:2005MGeol.215...23H. doi:10.1016/j.margeo.2004.11.006. Retrieved 1 November 2019.
  8. ^ Marco Bohnhoff; Fatih Bulut; Georg Dresen; Peter E. Malin; Tuna Eken; Mustafa Aktar (18 June 2013). "An earthquake gap south of Istanbul". Nature Communications. 4:1999: 1999. Bibcode:2013NatCo...4.1999B. doi:10.1038/ncomms2999. PMID 23778720.
  9. ^ a b c Erhan Afyouncu (26 September 2018). "Istanbul's nightmare: A timeline of earthquakes that shook the city". Daily Sabah. Retrieved 1 November 2019.
  10. ^ a b c d e f g h i N.N. Ambraseys; C. F. Finkel (1991). "Long-term seismicity of Istanbul and of the Marmara sea region" (PDF). Terra Nova. 3 (5): 527–539. Bibcode:1991TeNov...3..527A. doi:10.1111/j.1365-3121.1991.tb00188.x. Retrieved 26 October 2019.
  11. ^ Şevket Erşan (2–4 December 2015). A Comparative Evaluation of the Results of Two Earthquakes: Istanbul and Lisbon Earthquake in 18th Century. Proceedings of the 2nd International Conference on Historic Earthquake-Resistant Timber Frames in the Mediterranean Region – H.Ea.R.T.2015. LNEC, Portugal. Retrieved 31 October 2019.
  12. ^ a b Tom Parsons (22 May 2004). "Recalculated probability of M>=7 earthquakes beneath the Sea of Marmara, Turkey". Journal of Geophysical Research. 109 (B5): B05304. Bibcode:2004JGRB..109.5304P. doi:10.1029/2003JB002667. Retrieved 7 November 2019.
  13. ^ a b Mustapha Meghraoui; M. Ersen Aksoy; H Serdar Akyüz; Matthieu Ferry; Aynur Dikbaş; Erhan Altunel (2012). "Paleoseismology of the North Anatolian Fault at Güzelköy (Ganos segment, Turkey): Size and recurrence time of earthquake ruptures west of the Sea of Marmara". Geochemistry, Geophysics, Geosystems. 13 (4): n/a. Bibcode:2012GGG....13.4005M. doi:10.1029/2011GC003960. S2CID 8409966. Retrieved 1 November 2019.
  14. ^ Dietrich Lange; Heidrun Kopp; Jean-Yves Royer; Pierre Henry; Ziyadin Çakir; Florian Petersen; Pierre Sakic; Valerie Ballu; Jörg Bialas; Mehmet Sinan Özeren; Semih Ergintav; Louis Géli (2019). "Interseismic strain build-up on the submarine North Anatolian Fault offshore Istanbul". Nature Communications. 10 (1): 3006. Bibcode:2019NatCo..10.3006L. doi:10.1038/s41467-019-11016-z. PMC 6614505. PMID 31285439.
  15. ^ a b Robert Yeats (2015). Earthquake time bombs. Cambridge University Press. doi:10.1017/CBO9781316048184. ISBN 9781316048184. Retrieved 7 November 2019.
  16. ^ Korai Kamaci (19 October 2015). "Osmanlı Devlet'inde Depremler ve 1509 Büyük Depremi". Istiklal (in Turkish). Retrieved 31 October 2019.
  17. ^ Müller-Wiener 1977, p. 388.
  18. ^ Müller-Wiener 1977, p. 441.
  19. ^ Müller-Wiener 1977, p. 467.
  20. ^ Müller-Wiener 1977, p. 407.
  21. ^ Müller-Wiener 1977, p. 162.
  22. ^ Müller-Wiener 1977, p. 93.
  23. ^ "Damage to domes, minarets and historical structures" (PDF). Retrieved 7 November 2019.
  24. ^ Müller-Wiener 1977, p. 341.
  25. ^ Müller-Wiener 1977, p. 346.
  26. ^ Gülersoy, Çelik (1990). Story of the Grand Bazaar. Sultanahmet, İstanbul: İstanbul Kitaplıg. p. 12. ISBN 9789757687023. OCLC 28196009.

Sources edit