Çağlar ÖZKAYMAK, Halil İbrahim SOLAK, İbrahim TİRYAKİOĞLU, Orhan TATAR, Haluk ÖZENER, Bahadır AKTUĞ, Eda Esma EYÜBAGİL, Cemal Özer YİĞİT, Bengisu GELİN, Hasan SÖZBİLİR, Mustafa SOFTA

GPS derived finite source mechanism of the 30 October 2020 Samos earthquake, Mw = 6.9, in the Aegean extensional region

A submarine area close to the Turkish and Greek border between the cities of Samos-Greece and Seferihisar-Turkey has been shaked on October 30, 2020 by a Mw= 6.9 earthquake. In this study, the finite source mechanism of the Samos earthquake was investigated using geodetic methods and the coseismic behavior of the earthquake was modeled. The observed coseismic displacements at 62 sites were inverted for the fault geometry and the slips. The mainshock did not generate an on-land surface rupture. However, the uniform slip modeling shows a finite source of 43.1 km long and 16 km wide rupture, which slips 1.42 m along a north dipping normal fault extending from the Aegean Sea floor to a depth down to ~13 km. While the uniform slip model is consistent with the seismological solutions and provides a sufficient fit to the far field coseismic offsets, a distributed slip model is necessary to account for the near field coseismic displacements.

PDF

___

Akıncı A, Cheloni D, Dindar AA (2021). The 30 October 2020 Samos (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions. 12 February 2021, PREPRINT (Version 1) available at Research Square doi: 10.21203/rs.3.rs-215817/v1
Aktuğ B, Kılıçoğlu A (2006). Recent crustal deformation of İzmir, Western Anatolia and surrounding regions as deduced from repeated GPS measurements and strain field. Journal of Geodynamics 41 (5): 471-484. doi: 0.1016/j.jog.2006.01.004
Aktuğ B, Nocquet JM, Cingöz A, Parsons B, Erkan Y et al. (2009). Deformation of Western Turkey from a combination of permanent and campaign GPS data: limits to block-like behavior. Journal of Geophysical Research 114 (5): 1978-2012. doi: 10.1029/2008JB006000
Aktuğ B, Kaypak B, Çelik RN (2010). Source parameters for the Mw= 6.6, 03 February 2002, Çay Earthquake (Turkey) and aftershocks from GPS, Southwestern Turkey. Journal of Seismology 14(3):445-456. doi: 10.1007/s10950-009-9174-y
Altunel E, Pinar A (2021). Tectonic implications of the Mw 6.8, 30 October 2020 Kuşadası Gulf earthquake in the frame of active faults of Western Turkey. Turkish Journal of Earth Sciences 30: 436-448.
Ambraseys N (2009). Earthquakes in the Mediterranean and Middle East: a multidisciplinary study of seismicity up to 1900. New York, NY, USA: Cambridge University Press.
Brosolo L, Mascle J, Loubrieu B (2012). Morphobathymetric Map of the Mediterranean Sea. Paris, France: publication CCGM/ CGMW, UNESCO.
Caputo R. and Pavlides S (2013): The Greek Database of seismogenic sources (GreDaSS), version 2.0.0: A compilation of potential seismogenic sources (Mw > 5.5) in the Aegean Region. http:// gredass.unife.it/, doi: 10.15160/unife/gredass/0200
Çetin KÖ, Mylonakis G, Sextos A, Stewart JP (2020/02). Hellenic Association of Earthquake Engineering: Report 2020/02 Earthquake Engineering Association of Turkey Earthquake Foundation of Turkey Earthquake Engineering Research Institute (USA)Geotechnical Extreme Events Reconnaissance Association: Report GEER-069 doi: 10.18118/G6H088
Chamot-Rooke N, Dotmed Working Group (2005). DOTMED – Deep offshore tectonics of the Mediterranean: A synthesis of deep marine data in eastern Mediterranean. Mémoire de la Société géologique de France & American Association of Petroleum Geologists 177: 64.
Chatzipetros A, Kiratzi A, Sboras S, Zouros N, Pavlides S (2013). Active faulting in the north-eastern Aegean Sea Islands. Tectonophysics 597: 106-122. doi: 10.1016/j.tecto.2012.11.026
Çırmık A, Pamukçu O, Gönenç T, Kahveci M, Şalk M et al. (2017a). Examination of the kinematic structures in İzmir (Western Anatolia) with repeated GPS observations (2009, 2010 and 2011). Journal of African Earth Sciences 126: 1-12. doi: 10.1016/j.jafrearsci.2016.11.020
Dewey JF, Şengör AMC (1979). Aegean and surrounding regions: Complex multiplate and continuum tectonics in a convergent zone. Geological Society of America Bulletin 90 (1): 84-92. doi: 10.1130/0016-7606(1979)90<84:AASRCM>2.0.CO;2
Doğan G G, Yalçıner A C, Yüksel Y, Ulutaş E, Polat O et al. (2021). The 30 October 2020 Aegean Sea tsunami: post-event field survey along Turkish coast. Pure and Applied Geophysics. doi: 10.1007/s00024-021-02693-3
Elias P, Ganas A, Briole P, Valkaniotis S, Escartin J et al. (2021) Coseismic deformation, field observations and seismic fault model of the Oct. 30, 2020 Mw = 7.0 Samos earthquake, Aegean Sea, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21- 14595, https://doi.org/10.5194/egusphere-egu21-14595, 2021.
Elitez İ, Yaltırak C (2014). Burdur-Fethiye Shear Zone (Eastern Mediterranean, SW Turkey). In: EGU General Assembly 2014, Vienne, Austria.
Emre Ö, Duman TY, Özalp S, Şaroğlu F, Olgun Ş et al. (2018). Active fault database of Turkey. Bulletin of Earthquake Engineering 16 (8): 3229-3275. doi: 10.1007/s10518-016-0041-2
Ergin K, Güçlü U, Uz Z (1967). A catalogue of earthquakes of Turkey and surrounding area (11 A.D. to 1964 A.D.). İstanbul, Turkey: Maden Fakültesi Arz Fiziği Enstitüsü Yayınları.
Evelpidou N, Karkani A, Kampolis I (2021). Relative sea level changes and morphotectonic implications triggered by the Samos Earthquake of 30th October 2020. Journal of Marine Science and Engineering 9: 40. doi: 10.3390/jmse9010040
Eytemiz C, Erdeniz Ö F (2020). Investigation of active tectonics of Edremit Gulf, Western Anatolia (Turkey), using highresolution multi-channel marine seismic data. Marine Science and Technology Bulletin 9 (1): 51-57. doi: 10.33714/ masteb.635468
Havazlı E, Özener H. 2021. Investigation of strain accumulation along Tuzla fault - western Turkey. Turkish Journal of Earth Sciences 30:449-459
Eyübagil EE, Solak Hİ, Kavak US, Tiryakioğlu İ, Sözbilir H et al. (2021). Present-day strike-slip deformation within the southern part of İzmir Balıkesir Transfer Zone based on GNSS data and implications for seismic hazard assessment, western Anatolia. Turkish Journal of Earth Science 30: 143-160.
Fletcher R (1987). Practical Methods of Optimization. 2nd ed. New York, NY, USA: John Wiley & Sons.
Ganas A, Elias P, Briole P, Tsironi V, Valkaniotis S (2020). Fault responsible for Samos earthquake identified, Temblor. doi: 10.32858/temblor.134
Guidoboni, E, Comastri A, Traina G (1994). Catalogue of ancient earthquakes in the Mediterranean area up to the 10th century. Istituto Nazionale di Geofisica, Rome: 504 pp.
Guidoboni E, Comastri A, Boschi E (2005). The “exceptional” earthquake of 3 January 1117 in the Verona area (northern Italy): A critical time review and detection of two lost earthquakes (lower Germany and Tuscany). Journal of Geophysical Research: Solid Earth 110 (B12). doi: 10.1029/2005JB003683
Gülal E, Erdoğan H, Tiryakioğlu İ (2013). Research on the stability analysis of GNSS reference stations network by time series analysis. Digital Signal Processing 23: 1945-1957. doi: 10.1016/j. dsp.2013.06.014
Herring TA, King RW, Floyd MA, McClusky SC (2015). GAMIT Reference Manual, http://wwwgpsg.mit.edu/~simon/gtgk/ GAMIT_Ref.pdf
Herring TA, King RW, Floyd MA, McClusky SC (2015). Introduction to GAMIT/ GLOBK, http://wwwgpsg.mit.edu/~simon/gtgk/ Intro_GG.pdf
ISC (International Seismological center) (2020). Recent Earthquakes in Turkey [online]. Website http:// http://www.isc.ac.uk/ [accessed 4 November 2020].
Jackson J, McKenzie D (1984). Active tectonics of the Alpine– Himalayan Belt between western Turkey and Pakistan.
Geophysical Journal of the Royal Astronomical Society 77 (1): 185-264. doi: 10.1111/j.1365-246X.1984.tb01931.x Kirkpatrick S, Gelatt CD, Vecchi MP (1983). Optimization by Simulated Annealing Science 220: 671–680. doi: 10.1126/ science.220.4598.671
Kürçer A, Özalp S, Özdemir E, Güldoğan ÇU, Duman TY (2019). Active tectonic and paleoseismologic characteristics of the YeniceGönen fault, NW Turkey, in light of the 18 March 1953 YeniceGönen Earthquake (Ms = 7.2). Bulletin of the Mineral Research and Exploration 159: 29-62. doi: 10.19111/bulletinofmre.500553
Le Pichon X, Chamot-Rooke N, Lallemant S, Noomen R, Veis G (1995). Geodetic determination of the kinematics of central Greece with respect to Europe: impli-cations for eastern Mediterranean tectonics. Journal of Geophysical Research Atmospheres 100 (12): 675–690. doi: 10.1029/95JB0031.7
Lisowski M (1997). Postseismic strain following the 1989 Loma Prieta earthquake from GPS and leveling measurements. Journal of Geophysical Research 102: 4933–4955.
Lykousis V, Anagnostou C, Pavlakis P, Rousakis G, Alexandri M (1995). Quaternary sedimentary history and neotectonic evolution of the eastern part of the Central Aegean Sea, Greece, Marine Geology 128: 59-71. doi: 10.1016/0025-3227(95)00088-G
Mascle J, Martin L (1990). Shallow structure and recent evolution of the Aegean Sea: asynthesis based on continuous reflection profiles. Marine Geology 94 (4): 271–299. doi: 10.1016/0025- 3227(90)90060-W
McClusky S, Balasdsanian S, Barka A, Demir C, Georgiev I et al. (2000). Global positioning system constraints on crustal movements and deformations in the eastern Mediterranean and Caucasus. Journal of Geophysical Research 105 (B3): 5695–5719. doi: 10.1029/1999JB900351
McKenzie DP (1972). Active tectonics of the Mediterranean region. Geophysical Journal of the Royal Astronomical Society 30: 109– 185.
McKenzie DP (1978). Active tectonics of the Alpine–Himalayan belt: the Aegean Sea and surrounding regions. Geophysical Journal of the Royal Astronomical Society 55 (1): 217-254. doi: 10.1111/j.1365-246X.1978.tb04759.x.
Mozafari N, Tikhomirov D, Sumer Ö, Özkaymak Ç, Uzel B et al. (2019). Dating of active normal fault scarps in the Büyük Menderes Graben (western Anatolia) and its implications for seismic history. Quaternary Science Reviews 220: 111-123. doi: 10.1016/j.quascirev.2019.07.002
Ocakoğlu N, Demirbağ E, Kuşçu İ (2004). Neotectonic structures in the area offshore of Alacati, Doganbey and Kusadasi (Western Turkey): evidence of strike-slip faulting in the Aegean extensional province. Tectonophysics 391 (1-4): 67–83. doi: 10.1016/j.tecto.2004.07.008
Okada Y (1985). Surface deformation to shear and tensile faults in a halfspace. Bulletin of the Seismological Society of America 75 (4): 1135–1154.
Özener H, Doğru A, Acar M (2013). Determination of the displacements along the Tuzla fault (Aegean regionTurkey): Preliminary results from GPS and precise leveling techniques. Journal of Geodynamics 67: 13-20. doi: 10.1016/j. jog.2012.06.001
Özkaymak Ç, Sözbilir H (2008). Stratigraphic and structural evidence for fault reactivation: The active Manisa fault zone, Western Anatolia. Turkish Journal of Earth Sciences 17 (3): 615-635.
Özkaymak C, Sozbilir H, Uzel B (2013). Neogene-Quaternary evolution of the Manisa basin: Evidence for variation in the stress pattern of the İzmir-Balıkesir Transfer Zone, Western Anatolia. Journal of Geodynamics 65: 117–135. doi: 10.1016/j. jog.2012.06.004
Papadimitriou P, Kapetanidis V, Karakonstantis A, Spingos I, Kassaras I et al. (2020). First Results on the Mw=6.9 Samos Earthquake of 30 October 2020. Bulletin of the Geological Society of Greece 56 (1): 251-279. doi: 10.12681/bgsg.25359
Papanikolaou D, Alexandri M, Nomikou P, Ballas D (2002). Morphotectonic structure of the western part of the North Aegean Basin based on swath bathymetry. Marine Geology 190: 465–492. doi: 10.1016/S0025-3227(02)00359-6
Papazachos BC, Comninakis PE (1971). Geophysical and tectonic features of the Aegean Arc. Journal of Geophysical Research 76 (35): 8517-8533. doi: 10.1029/ JB076i035p08517
Reilinger R, McClusky S, Vernant P, Lawrence S, Ergintav S et al. (2006). 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 Atmospheres 111 (B5): B05411. doi: 10.1029/2005JB004051
Papazachos BC, Papazachou CB (1997). The earthquakes of Greece. Ziti Publishing, Grecee, Thessaloniki: pp 304.
Pavlides S, Tsapanos T, Zouros N, Sboras S, Koravos G et al. (2009). Using Active Fault Data for Assessing Seismic Hazard: A Case Study from NE Aegean Sea, Greece. In: Earthquake Geotechnical Engineering Satellite Conference XVIIth International Conference on Soil Mechanics & Geotechnical Engineering; Alexandria, Egypt. pp 1-14.
Pınar N, Lahn E (1952). Türkiye depremleri izahlı kataloğu. Bayındırlık Bakanlığı Yapı ve İmar İşleri Reisliği Yayınları, Türkiye: 36 (6) (in Turkish).
Reddy CD, Sunil PS (2008). Post-seismic crustal deformation and strain rate in Bhuj region, western India, after the 2001 January 26 earthquake. Geophysical Journal International 172 (2): 593– 606. doi: 10.1111/j.1365-246X.2007.03641.x
Reilinger R, McClusky S, Paradissis D, Ergintav S, Vernant P (2010). Geodetic constraints on the tectonic evolution of the Aegean region and strain accumulation along the Hellenic subduction zone. Tectonophysics 488 (1): 22–30. doi: 10.1016/j. tecto.2009.05.027
Sboras S, Pavlides S, Riccardo Caputo, Chatzipetros A, Michailidou A et al. (2011). Improving the resolution of seismic hazard estimates for critical facilities: the Database of Greek crustal seismogenic sources in the frame of the SHARE project. In: 30° Convegno Nazionale di Gruppo Nazionale di Geofisica della Terra Solida.
Soysal H, Sipahioğlu S, Kolçak D, Altınok Y (1981). Türkiye ve Çevresinin Tarihsel Deprem Kataloğu (2100 B.C.–1900 A.D.). TÜBİTAK, Rapor No: TBAG-341 (in Turkish).
Sözbilir H, Uzel B, Sumer O, Inci U, Yalcin-Ersoy E et al. (2008). Evidence for a kinematically linked EW trending İzmir Fault and NE-trending Seferihisar Fault: kinematic and paleoseismogical studies carried out on active faults forming the İzmir Bay, Western Anatolia. Geological Bulletin of Turkey 51 (2): 91-114.
Sözbilir H, Sümer Ö, Uzel B, Ersoy Y, Erkül F et al. (2009). The Seismic geomorphology of the Sığacık Gulf (İzmir) earthquakes of October 17 to 20, 2005 and their relationships with the stress field of their Western Anatolian region. Geological Bulletin of Turkey 52 (2): 217-238.
Sözbilir H, Sarı B, Uzel B, Sümer Ö, Akkiraz S (2011). Tectonic implications of transtensional supradetachment basin development in an extension-parallel transfer zone: the Kocaçay Basin, Western Anatolia. Turkey. Basin Research 23 (4): 423–448. doi: 10.1111/j.1365-2117.2010.00496.x
Sözbilir H, Sümer Ö, Uzel B, Eski S, Tepe Ç et al. (2017). 12 Haziran 2017 Midilli Depremi (Karaburun Açıkları) ve Bölgenin Depremselliği. Dokuz Eylül Üniversitesi Deprem Araştırma ve Uygulama Merkezi Raporu, 14s, http://daum.deu.edu. tr/?page_id=111&lang=tr
Sözbilir H, Tatar O, Akgün M, Ankaya P, Oya B et al. (2020). 30 Ekim 2020 Sisam (Samos) Depremi (mw: 6,9) Değerlendirme Raporu. doi: 10.13140/RG.2.2.33392.48644
Stucchi M, Rovida A, Capera AG, Alexandre P, Camelbeeck T et al. (2013). The SHARE European Earthquake Catalogue (SHEEC) 1000–1899. Journal of Seismology 17 (2): 523-544. doi: 10.1007/s10950-012-9335-2
Sümer Ö (2015). Evidence for the reactivation of a pre-existing zone of weakness and its contributions to the evolution of the Küçük Menderes Graben: a study on the Ephesus Fault, Western Anatolia, Turkey, Geodinamica Acta 27 (2-3): 130-154.
Tan O, Tapırdamaz MC, Yörük A (2008). The earthquake catalogues for Turkey. Turkish Journal of Earth Sciences 17 (2): 405-418.
Tan O, Papadimitriou EE, Pabuçcu Z, Karakostas V, Yörük A et al. (2014). A detailed analysis of microseismicity in Samos and Kusadasi (Eastern Aegean Sea) areas. Acta Geophysica. 62 (6): 1283-1309. doi: 10.2478/s11600-013-0194-1
Taxeidis K (2003). Study of historical seismicity of the Eastern Aegean Islands. PhD, National and Kapodistrian University of Athens, Athens, Greece (in Greek).
Taymaz T, Jackson J, McKenzie D (1991). Active tectonics of Alpine–Himalayan Belt between western Turkey and Pakistan. Geophysical Journal Research Astronomy Society 77: 185–265 doi: 10.1111/j.1365-246X.1984.tb01931.x
Tiryakioğlu İ, Floyd M, Erdoğan S, Gülal E, Ergintav S et al. (2013). GPS constraints on active deformation in the Isparta Angle region of SW Turkey. Geophysical Journal International 195 (3): 1455-1463. doi: 10.1093/gji/ggt323
Tiryakioğlu İ (2015). Geodetic aspects of the 19 May 2011 Simav earthquake in Turkey. Geomatics, Natural Hazards and Risk 6 (1): 76-89. doi: 10.1080/19475705.2013.831379
Tiryakioğlu İ, Baybura T, Özkaymak Ç, Sözbilir H, Sandıkçıoğlu A et al. (2015). Sultandağı Fayı Batı Kısmı Fay Aktivitelerinin Multidisipliner Çalışmalarla Belirlenmesi. Harita Teknolojileri Elektronik Dergisi 7 (1): 7-16 (In Turkish). doi: 10.15659/ hartek.15.01.60
Tiryakioğlu İ, Yavaşoğlu H, Uğur MA, Özkaymak Ç, Yılmaz M et al. (2017a). Analysis of October 23 (Mw 7.2) and November 9 (Mw 5.6), 2011 Van Earthquakes Using Long-Term GNSS Time Series. Earth Sciences Research Journal 21 (3): 147-156. doi: 10.15446/esrj.v21n3.62812
Tiryakioğlu İ, Yiğit CÖ, Yavaşoğlu H, Saka MH, Alkan RM (2017b). The determination of interseismic, coseismic and postseismic deformations caused by the Gökçeada-Samothraki earthquake (2014, Mw = 6.9) based on GNSS data. Journal of African Earth Sciences 133: 86-94. doi: 10.1016/j.jafrearsci.2017.05.012
Tiryakioğlu İ, Aktuğ B, Yiğit CÖ, Yavaşoğlu HH, Sözbilir H et al. (2018a). Slip distribution and source parameters of the 20 July 2017 Bodrum-Kos earthquake (Mw6.6) from GPS observations. Geodinamica Acta 30 (1): 1-14. doi: 10.1080/09853111.2017.1408264
Tiryakioğlu İ, Uğur MA, Özkaymak Ç (2018b). Determination of Surface Deformations with Global Navigation Satellite System Time Series. Journal of Geological and Environmental Engineering 12 (11). doi: 10.5281/zenodo.2022043
Tiryakioğlu İ, Yiğit CÖ, Baybura T, Yılmaz M, Uğur MA et al. (2019). Active surface deformations detected by precise levelling surveys in the Afyon-Akşehir Graben, Western Anatolia, Turkey. Geofizika 36: 34-51. doi: 10.15233/gfz.2019.36.4
Tur H, Yaltırak C, Elitez İ, Sarıkavak KT (2015). Pliocene–Quaternary tectonic evolution of the Gulf of Gökova, southwest Turkey. Tectonophysics 638: 158–176. doi: 10.1016/j.tecto.2014.11.008
Vernant P, Reilinger R, McClusky S (2014). Geodetic evidence for low coupling on the Hellenic subduction plate interface. Earth and Planetary Science Letters 385: 122-129. doi: 10.1016/j. epsl.2013.10.018
Wang L, Wang R, Roth F, Enescu B, Hainzl S et al. (2009). Afterslip and viscoelastic relaxation following the 1999 M 7.4 Izmit earthquake from GPS measurements. Geophysical Journal International 178 (3): 1220–1237.
Wessel P, Luis JF, Uieda L, Scharroo R, Wobbe F et.al. (2019). The Generic Mapping Tools version 6. Geochemistry, Geophysics, Geosystems 20: 5556–5564. doi: 10.1029/2019GC008515
Yaltırak C (2002). Tectonic evolution of the Marmara Sea and its surroundings. Marine Geology 190: 493–530. doi: 10.1016/ S0025-3227(02)00360-2
Yaltırak C, İşler EB, Aksu AE, Hiscott RN (2012). Evolution of the Bababurnu Basin and shelf of the Biga Peninsula: western extension of the middle strand of the Northeast Aegean Sea, Turkey. Journal of Asian Earth Sciences 57: 103–119. doi: 10.1016/j.jseaes.2012.06.016