Teleseismic Source Process of The October 30, 2020 Kuşadası Gulf –İzmir (Turkey) Earthquake (Mw=6.8)

Year 2020, Volume: 1 Issue: 2, 66 - 73, 01.12.2020

Murat Utkucu , Emrah Budakoğlu , Şefik Ramazanoğlu

Abstract

The October 30, 2020 Kuşadası Gulf-İzmir earthquake took place along a fault bounding Kuşadası Gulf in the South causing significant damage and loss of life, especially in İzmir city. The earthquake damage due to the strong ground motion is augmented by a tsunami that caused a water inundation. In the present study the source properties of the earthquake are investigated by inverting teleseismic P waveforms. The complex waveforms are fit with two subevents in the point-source inversion that requires dominant normal faulting along a roughly E-W trending normal fault dipping north. The finite-source inversion shows that the earthquake is due to failure of a two asperities with slip as high as 2.4 m and the rupture covers a fault area of 30 km x 20 km with unilateral propagation toward west. The finite-source model defines two asperities that are located at hypocentral area and shallow depths near the west top corner of the fault. The earthquake rupture lasts for 17 s and released a seismic moment of 2.21 x 1019 Nt.m (MW=6.83). Presence of a shallow asperity indicates that rupture reaches to the sea bottom which provides a reasonable explanation for the damaging tsunami.

Keywords

The 2020 Kuşadası Gulf-İzmir earthquake, teleseismic point-source inversion, teleseismic finite-source inversion, Extensional tectonics

References

• [1] Reilinger, R., McClusky, S., Vernant, P., Lawrence, S., Ergintav, S., Cakmak, R., et al. GPS constraints on continental deformation in the Africa‐Arabia‐Eurasia continental collision zone and implications for the dynamics of plate interactions. Journal of Geophysical Research: Solid Earth, 2006; 111-B5.
• [2] Jolivet, L., Faccenna, C., Huet, B., Labrousse, L., Le Pourhiet, L., Lacombe, O., et al. Aegean tectonics: Strain localisation, slab tearing and trench retreat. Tectonophysics, 2013; 597, 1-33.
• [3] Koçyiğit, A. Tectonis of Hoyran Lake (Isparta Bend) region, Türk Jeol. Kurumu Bül., 1983; 26, 1-10 (in Turkish).
• [4] Koçyiğit, A. Güneybatı Türkiye ve yakın dolayının levha içi yeni tektonik gelişim, Türkiye Jeol. Kur. Bült., 1984; 27, 1-16 (in Turkish).
• [5] Jackson, J. and McKenzie, D. P. Active tectonics of the Alpine-Himalayan belt between western Turkey & Pakistan, Geophysical Journal International, 1984; 77(1), 185-264.
• [6] Eyidoğan, H. and Jackson, J. A seismological study of normal faulting in the Demirci, Alaşehir and Gediz earthquakes of 1969–70 in western Turkey: Implications for the nature and geometry of deformation in the continental crust. Geophysical Journal International, 1985; 81(3), 569-607.
• [7] Taymaz, T., Jackson, J. and McKenzie, D. Active tectonics of the north and central Aegean Sea. Geophysical Journal International, 1991; 106(2), 433-490.
• [8] Aktuğ, B., Nocquet, J. M., Cingöz, A., Parsons, B., Erkan, Y., England, P. et al. A. Deformation of western Turkey from a combination of permanent and campaign GPS data: Limits to block‐like behavior. Journal of Geophysical Research: Solid Earth, 2009; 114(B10).
• [9] KOERI (Kandilli Observatory and Earthquake Research Institute), 30 Ekim 2020 Ege Denizi Depremi Basın Bülteni, 2020; 8 sf.
• [10] AFAD (Disaster and Emergency Management Presidency), 30 Ekim 2020 Ege Denizi, Seferihisar (İzmir) Açıkları (17,26 Km) Mw=6.6 Depremine İlişkin Ön Değerlendirme Raporu, 2020; 10 sf.
• [11] Yalçıner, A. C., Doğan, G. G., Ulutaş, E., Polat, O., Tarih, A., Yapar, E. R. et al. The 30 October 2020 (11:51 Utc) İzmır-Samos Earthquake and Tsunami; Post-Tsunami Field Survey Preliminary Results, 2020; 33 pp.
• [12] Papazachos B.C. and Papazachou C.B. The earthquakes of Greece. Ziti Publication, Thessaloniki, 1997; 304 pp.
• [13] Ambraseys, N. Earthquakes in the Mediterranean and Middle East: a multidisciplinary study of seismicity up to 1900. Cambridge University Press, 2009.
• [14] Kalafat, D., Kekovalı, K., Güneş, Y., Yılmazer, M., Kara, M., Deniz, P., et al. A Cataloque of Source Parameters of Moderate and Strong Earthquakes for Turkey and its Surrounding Area (1938–2008). Boğaziçi University Publication, 2009; (1026).
• [15] Kızılbuğa, S, Utkucu M, Yalçın H, Turan, F, Coşkun, Z., Kalkan, E, Pınar A. Monitoring and Relocating the Aftershock Sequence of the June 12, 2017 Karaburun-Lesvos Earthquake (Mw=6.3) VI. International Earthquake Symposium Kocaeli 2019 (IESKO 2019), Proceeding Book, p933-937 September 25-27, 2019, Kocaeli, TurkeyISBN:, 2019; 978-605-69403-1-6.
• [16] Aktar, M., Karabulut, H., Özalaybey, S. and Childs, D. A conjugate strike-slip fault system within the extensional tectonics of Western Turkey. Geophysical Journal International, 2007; 171(3), 1363-1375.
• [17] Jeffreys, H. and Bullen, K. E. Seismological tables//Brit. Assoc. for the advancement of Sci. London: Gray-Milne Trust, 1958; 65.
• [18] Kikuchi, M. and Kanamori, H. Inversion of complex body waves—III. Bulletin of the Seismological Society of America, 1991; 81(6), 2335-2350.
• [19] Özer, Ç., Polat, O., İzmir ve çevresinin 3-B kabuk hız yapısı. Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, 2017, 32.3.
• [20] Kikuchi, M., M. Nakamura, and K.Yoshikawa. Source rupture processes of the 1944 Tonankai earthquake and the 1945 Mikawa earthquake derived from low-gain seismograms, Earth Planets Space, 2003; 55, 159-172.
• [21] Kohketsu, K. The extended reflectivity method for synthetic near-field seismogram. Journal of Physics of the Earth, 1985; 33(2), 121-131.
• [22] Tiryakioğlu, İ., Aktuğ, B., Yiğit, C. Ö., Yavaşoğlu, H. H., Sözbilir, H., Özkaymak, Ç., et al. Slip distribution and source parameters of the 20 July 2017 Bodrum-Kos earthquake (Mw6. 6) from GPS observations. Geodinamica acta, 2018; 30(1), 1-14.
• [23] Utkucu, M. and Kızılbuğa S. Analysis of the background seismicity and teleseismic source process of the July 20, 2017 Bodrum-Kos earthquake 5. International Conference on Earthquake Engineering and Seismology (5ICEES), 8-11 October 2019, METU Ankara, Turkey, 2019; 10 pp.