Seismological and Seismotectonic Characteristics of Earthquake Swarm in the Southern Nisyros Basin of the Aegean Sea

Abstract

In this study, the temporal and spatial characteristics of the seismological parameters of the earthquake swarm occurred in the NE-SW direction on the Southern Nisyros Basin in east of the Aegean Cycladic Volcanic Arc between 1 April 2021 and 4 October 2021 was investigated. The focal mechanism solutions of 20 earthquakes with magnitude ML≥4.0 between the relevant dates show that the NW-SE direction tectonic extension is active throughout the basin. It has been determined that the normal faults controlling both sides of the basin are responsible for the swarm. The completeness magnitude representing the earthquake swarm was Mc=2.7, and the Gutenberg-Richter (G-R) equation was found to be LogN(ML)=0.86*ML-5.55 for the annual a-value. In the comparison of the temporal and spatial patterns of the earthquake activity and G-R variables in the region before and after April 1, 2021, the seismicity patterns and G-R values showed significant differences. It was observed that the earthquake swarm after 1 April 2021 occurred in an area between low b-value (high stress) and high b-value (low stress) that developed in the previous period.

Keywords

• Earthquake swarm
• Extensional tectonics
• Completeness magnitude
• b-value
• Active fault

Ege Denizi Güney İncirli Havzası Deprem Fırtınasının Sismolojik ve Sismotektonik Özellikleri

Abstract

Bu çalışmada, Ege Kiklad Volkan Yayı'nın doğusunda yer alan Güney İncirli Havzası’nda 1 Nisan 2021-4 Ekim 2021 tarihleri arasında KD-GB doğrultusunda oluşan deprem fırtınasının sismolojik özelliklerinin zaman ve mekânda değişimi incelenmiştir. İlgili tarihler arasında büyüklüğü ML≥4.0 olan 20 depremin odak mekanizması çözümleri, KB-GD yönündeki tektonik genişlemenin havza boyunca aktif olduğunu göstermektedir. Havzanın her iki tarafını denetleyen normal fayların deprem fırtınasından sorumlu olduğu saptanmıştır. Deprem fırtınasını temsil eden tamlık büyüklüğü Mc=2.7, Gutenberg-Richter (G-R) denklemi ise yıllık a-değeri için LogN(ML)=0.86*ML-5.55 olarak bulunmuştur. 1 Nisan 2021 öncesi ve sonrası dönemde bölgedeki deprem etkinliğinin ve G-R değişkenlerinin zamansal ve mekânsal dağılımları kıyaslandığında, depremsellik örüntüleri ve G-R değerleri önemli farklılıklar göstermiştir. 1 Nisan 2021 sonrası deprem etkinliğinin daha önceki dönemde gelişen düşük b-değeri (yüksek gerilim) ve yüksek b-değeri (düşük gerilim) arasında kalan bir alanda oluştuğu gözlenmiştir.

Keywords

• Deprem fırtınası
• Genişleme tektoniği
• Deprem büyüklüğü tamlığı
• b-değeri
• Aktif fay

References

1. Aktug B., Nocquet J.M., Cingoz A., Parsons, Erkan Y., England P., Lenk O. Gurdal M.A., Kilicoglu A., Akdeniz H., Tekgul A., 2009. Deformation of western Turkey from a combination of permanent and campaign GPS data: Limits to block-like behavior, J. Geophys. Res. 114, B10404, 1-22
2. Chatzipetros A., Kiratzi A.A., Sboras S., Zouros N., 2013. Active faulting in the north-eastern Aegean Sea Islands, Tectonophysics 106, 597-598
3. Chiba K., Shimizu H., 2018. Spatial and temporal distributions of b-value in and around Shinmoe-dake, Kirishima volcano, Japan. Earth Planets and Space, 70(1), art. no. 122
4. Cossette E., Audet P., Schneider D., Grasemann B., 2016. Structure andanisotropy of the crust in the Cyclades, Greece, using receiver functions constrained by in situ rock textural data, J. Geophys. Res. Solid Earth 121, 2661-2678
5. Dietrich V., Lagios E., 2018. Nisyros Volcano: The Kos-Yali-Nisyros Volcanic Field; Springer: Berlin/Heidelberg, Germany, 339 p.
6. Endrun B., Meier T., Lebedev S., Bohnhoff M., Stavrakakis G., Harjes H.P., 2008. S-velocity structure and radial anisotropy in the Aegean region from surface wave dispersion, Geophys. J. Int. 174, 593-616
7. Eyidogan H., 2020. Investigation of the temporal and spatial properties of earthquake activity and Gutenberg- Richter parameters in the vicinity of Manisa Akhisar, Turk. J. Earthq. Res. 2(2), 138-159
8. Fischer T., Horalek J., Michalek J., Bouskova, A., 2010. The 2008 West Bohemia earthquake swarm in the light of the WEBNET network, J. Seism. 14(4), 665-682

9. Floyd M.A., Billiris H., Paradissis D., Veis G., Avallone A., Briole P., McClusky S., Nocquet J.M., Palamartchouk K., Parsons B., England, P. C., 2010. A new velocity field for Greece: Implications for the kinematics and dynamics of the Aegean, J. Geophys. Res. 115, B10403, 1-25
10. Heinicke J., Woith H., Alexandrakis C., Buske S., Telesca, L., 2018. Can hydroseismicity explain recurring earthquake swarms in NW‐Bohemia, Geophys. J. Int. 212(1), 211-228
11. Hicks S.P., Verdon J., Baptie B., Luckett R., Mildon Z.K., Gernon T., 2019. A shallow earthquake swarm close to hydrocarbon activities: discriminating between natural and induced causes for the 2018-2019, Surrey, United Kingdom, Earthquake Sequence, Seismol. Res. Lett. 90(6), 2095-2110
12. Hollenstein C., Müller M.D., Geiger A, Kahle H-G., 2008. Crustal motion and deformation in Greece from a decade of GPS measurements, 1993-2003, Tectonophysics 449(1), 17-40
13. Mcclusky S., Balassanian S., Barka A, Demir C., Ergintav S., Georgiev I., Gurkan O, Hamburger M., Hurst K., Kahle H., Kastens K., Kekelidze G., King R., Kotzev V., Lenk O., Mahmoud S., Mishin A., Nadariya M., Ouzounis A., Paradissis D., Peter Y., Prilepin M., Reilinger R., Sanli I., Seeger H., Tealeb A., Toksöz M.N., Veis G., 2000. Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus, J. Geophys. Res. 105(B3), 5695-5719
14. Meade, B.J., Hager B.H., 2005. Block models of crustal motion in southern California constrained by GPS measurements, J. Geophys. Res. 110, B03403, 1-19
15. Mountrakis D., 2005. Tertiary and Quaternary tectonics in Aegean area, Developments in Volcanology 7, 1-10
16. NOA, 2021. Institude of Geodynamics, National Observatory of Athens, NOAIG-Catalogue (1964 up to today). Erişim adresi: https://www.gein.noa.gr/en/services-products/earthquake-catalogs/
17. Nocquet J.M., 2012. Present-day kinematics of the Mediterranean: A comprehensive overview of GPS results. Tectonophysics 579, 220-242
18. Nomikou P., Bell K.L.C., Papanikolaou D., Livanos I., Fero Martin, J., 2013. Exploring the Avyssos-Yali-Strogyli submarine volcanic complex at the eastern edge of the Aegean Volcanic Arc, Zeitschrift für Geomorphologie 57(3), 125-137
19. Nomikou P., Krassakis P., Kazana S., Papanikolaou D., Koukouzas N., 2021 The volcanic relief within the Kos-Nisyros-Tilos tectonic graben at the eastern edge of the Aegean Volcanic Arc, Greece and Geohazard Implications, Geosciences 11, 231, 1-22
20. Nomikou P., Papanikolaou D., 2011. Extension of active fault zones on Nisyros Volcano across the Yali-Nisyros channel based on onshore and offshore data, Marine Geophysical Research 32(1-2),181-192
21. Nyst M., Thatcher W., 2004. New constraints on the active tectonic deformation of the Aegean, J. Geophys. Res. 109, B11406, 1-23
22. Ocakoglu N., Demirbag E., Kuscu I., 2005. 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, 67-83
23. Ozturk S., 2019. Region-Time-Magnitude Analyses of the Seismicity in and around the Central Anatolian Region and Current Earthquake Potential, Turk. J. Earthq. Res. 1(2), 148-166
24. Papazachos B.C., Dimitriadis S.T., Panagiotopoulos D.G., Papazachos C.B., Papadimitriou E.E., 2005. Deep structure and active tectonics of the southern Aegean volcanic arc, Developments in Volcanology 7, 47-64
25. Pe-Piper G., Piper D.J.W., 2005. The South Aegean active volcanic arc: Relationships between magmatism and tectonics, Developments in Volcanology 7, 113-133
26. Reilinger R., McClusky S., Vernant P., et al., 2006. GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interactions, J. Geophys. Res. 111, B05411, 1-26
27. Scholz C.H., 2015. On the stress dependence of the earthquake b value. Geophys. Res. Lett. 42, 1399-1402
28. Sengor A.M.C, Tuysuz O., Imren C., Sakinc M., Eyidogan H., Gorur N., Le Pichon X., Rangin C., 2005. The North Anatolian Fault: A New Look, Annu. Rev. Earth Planet. Sci. 33, 37-112
29. Shaw B., Jackson J., 2010. Earthquake mechanisms and active tectonics of the Hellenic subduction zone, Geophys. J. Int. 181(2), 966-984
30. Shibutani T., Nakao S., Nishida R., Takeuchi F., Watanabe K., Umeda Y., 2002. Swarm-like seismic activity in 1989, 1990 and 1997 preceding the 2000 Western Tottori earthquake, Earth Planets and Space, 54, 831-845
31. 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
32. Wiemer S., 2001. A software package to analyze seismicity: ZMAP, Seismol. Res. Lett. 72(3), 373-382
33. Wiemer S., Wyss M., 2000. Minimum magnitude of completeness in earthquake catalogs: examples from Alaska, the western United States, and Japan, Bull. Seism. Soc. Am. 90(4), 859-869
34. Zhu L., Mitchell B. J., Akyol N., Cemen I., Kekovali K., 2006. Crustal thickness variations in the Aegean region and implications for the extension of continental crust, J. Geophys. Res. 111, B01301, 1-10