Spatiotemporal characteristics and earthquake statistics of the 2020 and 2022 adjacent earthquake sequences in North Aegean Sea (Greece)




ETAS, Seismotectonics, North Aegean, Damage zones, Earthquake relocation


The two moderate earthquakes that occurred close and to the north of the North Aegean Trough (NAT) on 26 September 2020 (Mw5.3) and 16 January 2022 (Mw5.4), both followed by aftershock activity, are examined. Seismic activity along the NAT and its parallel branches is continuous and remarkable, with numerous strong instrumental (M≥6.0) earthquakes. Yet, the frequency of moderate (5.0≤M<6.0) earthquakes outside these major fault branches is rather rare and therefore their investigation provides the optimal means to decipher the seismotectonic properties of the broader area. The temporal and spatial proximity of the two seismic excitations from late September of 2020 through early 2022, intrigues for exhaustive investigation of seismic activity with the employment of earthquake relocation techniques, moment tensor solutions and statistical analysis. Our research revealed that this seismic activity purely falls inside the Mainshock – Aftershock type, with fast aftershock decay rates and moderate productivity. According to our findings, the two seismic sequences, despite their close proximity, exhibit distinctive features as a result of the intricate stress field generated at the western termination of the NAF system in an extensional domain.


Chu, A., Schoenberg, F., Bird, P., Jackson, D., & Kagan, Y. (2011). Comparison of ETAS Parameter Estimates across Different Global Tectonic Zones. Bulletin of the Seismological Society of America, 101(5), 2323–2339. DOI:

Drakopoulos, J., & Ekonomides, A. (1972). Aftershocks of February 19, 1968 earthquake in Northern Aegean Sea and related problems. Pure and Applied Geophysics PAGEOPH, 95(1), 100–115. DOI:

Hainzl, S., & Ogata, Y. (2005). Detecting fluid signals in seismicity data through statistical earthquake modeling. Journal of Geophysical Research: Solid Earth, 110(B5). DOI:

Hatzfeld, D., Ziazia, M., Kementzetzidou, D., Hatzidimitriou, P., Panagiotopoulos, D., Makropoulos, K., Papadimitriou, P., & Deschamps, A. (1999). Microseismicity and focal mechanisms at the western termination of the North Anatolian Fault and their implications for continental tectonics. Geophysical Journal International, 137(3), 891–908. DOI:

Heimann, S., Isken, M., Kuhn, D., Sudhaus, H., Steinberg, A., Daout, S., Cesca, S., Vasyura-Bathke, H., & Dahm, T. (2018). Grond—A probabilistic earthquake source inversion framework V1.0 [Computer software. GFZ Data Services.

Heimann, S., Kriegerowski, M., Isken, M., Cesca, S., Daout, S., Grigoli, F., Juretzek, C., Megies, T., Nooshiri, N., Steinberg, A., Sudhaus, H., Vasyura-Bathke, H., Willey, T., & Dahm, T. (2017). Pyrocko-An open-source seismology toolbox and library [Computer software. GFZ Data Services.

Kapetanidis, V., & Kassaras, I. (2019). Contemporary crustal stress of the Greek region deduced from earthquake focal mechanisms. Journal of Geodynamics, 123, 55–82. DOI:

Karabulut, H., Roumelioti, Z., Benetatos, C., Ahu Kömec Mutlu, Özalaybey, S., Aktar, M., & Kiratzi, A. (2006). A source study of the 6 July 2003 (Mw 5.7) earthquake sequence in the Gulf of Saros (Northern Aegean Sea): Seismological evidence for the western continuation of the Ganos fault. Tectonophysics, 412(3–4), 195–216. DOI:

Karakostas, B., Hatzidimitriou, P., Karakaisis, G., Papadimitriou, E., & Papazachos, B. (1986). Evidence for long–term precursors of strong earthquakes in the northernmost part of the Aegean Sea. Earthquake Prediction Research, 4, 155–164.

Karakostas, V., Papadimitriou, E., Karakaisis, G., Papazachos, C., Scordilis, E., Vargemezis, G., & Aidona, E. (2003). The 2001 Skyros, Northern Aegean, Greece, earthquake sequence: Off—Fault aftershocks, tectonic implications, and seismicity triggering. Geophysical Research Letters, 30(1). DOI:

Karakostas, V., Papadimitriou, E., & Gospodinov, D. (2014). Modelling the 2013 North Aegean (Greece) seismic sequence: geometrical and frictional constraints, and aftershock probabilities. Geophysical Journal International, 197(1), 525–541. DOI:

Kim, Y.S., Andrews, J., & Sanderson, D. (2000). Damage zones around strike-slip fault systems and strike-slip fault evolution, Crackington Haven, southwest England. Geosciences Journal, 4(2), 53–72. DOI:

Kiratzi, A., Wagner, G., & Langston, C. (1991). Source parameters of some large earthquakes in Northern Aegean determined by body waveform inversion. Pure and Applied Geophysics PAGEOPH, 135(4), 515–527. DOI:

Kiratzi, A., Tsakiroudi, E., Benetatos, C., & Karakaisis, G. (2016). The 24 May 2014 (Mw6.8) earthquake (North Aegean Trough): Spatiotemporal evolution, source and slip model from teleseismic data. Physics and Chemistry of the Earth, Parts A/B/C, 95, 85–100. DOI:

Kissling, E., Ellsworth, W., Eberhart‐Phillips, D., & Kradolfer, U. (1994). Initial reference models in local earthquake tomography. Journal of Geophysical Research: Solid Earth, 99(B10), 19635–19646. DOI:

Klein, F. (2002). User’s guide to HYPOINVERSE-2000, a Fortran program to solve for earthquake locations and magnitudes. Publisher is required!. DOI:

Konstantinou, K. (2017). Accurate relocation of seismicity along the North Aegean Trough and its relation to active tectonics. Tectonophysics, 717, 372–382. DOI:

Konstantinou, K., Mouslopoulou, V., Liang, W., Heidbach, O., Oncken, O., & Suppe, J. (2017). Present-day crustal stress field in Greece inferred from regional-scale damped inversion of earthquake focal mechanisms. Journal of Geophysical Research: Solid Earth, 122(1), 506–523. DOI:

Kourouklas, C., Mangira, O., Iliopoulos, A., Chorozoglou, D., & Papadimitriou, E. (2020). A study of short-term spatiotemporal clustering features of Greek seismicity. Journal of Seismology, 24(3), 459–477. DOI:

Kourouklas, C., Papadimitriou, E., Tsaklidis, G., & Karakostas, V. (2018). Earthquake recurrence models and occurrence probabilities of strong earthquakes in the North Aegean Trough (Greece). Journal of Seismology, 22(5), 1225–1246. DOI:

Kourouklas, C., Console, R., Papadimitriou, E., Murru, M., & Karakostas, V. (2021). Modelling the large earthquakes recurrence times along the North Aegean Trough Fault Zone (Greece) with a physics-based simulator, Geophys. Geophysical Journal International, 225(3), 2135–2156. DOI:

Kourouklas, C., Tsaklidis, G., Papadimitriou, E., & Karakostas, V. (2022). Analyzing the Correlations and the Statistical Distribution of Moderate to Large Earthquakes Interevent Times in Greece. Applied Sciences, 12(14), 7041. DOI:

Pichon, X., & Angelier, J. (1979). The hellenic arc and trench system: A key to the neotectonic evolution of the eastern mediterranean area. Tectonophysics, 60(1–2), 1–42. DOI:

Llenos, A., & Michael, A. (2013). Modeling Earthquake Rate Changes in Oklahoma and Arkansas: Possible Signatures of Induced Seismicity. Bulletin of the Seismological Society of America, 103(5), 2850–2861. DOI:

Lombardi, A. (2015). Estimation of the parameters of ETAS models by Simulated Annealing. Scientific Reports, 5(1). DOI:

Lombardi, A. (2017). SEDA: A software package for the Statistical Earthquake Data Analysis. Scientific Reports, 7(1). DOI:

Massey, F. (1951). The Kolmogorov-Smirnov Test for Goodness of Fit. Journal of the American Statistical Association, 46(253), 68–78. DOI:

McKenzie, D. (1972). Active Tectonics of the Mediterranean Region. Geophysical Journal International, 30(2), 109–185. DOI:

Ogata, Y. (1988). Statistical Models for Earthquake Occurrences and Residual Analysis for Point Processes. Journal of the American Statistical Association, 83(401), 9–27. DOI:

Ogata, Y. (1992). Detection of precursory relative quiescence before great earthquakes through a statistical model. Journal of Geophysical Research: Solid Earth, 97(B13), 19845–19871. DOI:

Ogata, Y. (1998). Space-Time Point-Process Models for Earthquake Occurrences. Annals of the Institute of Statistical Mathematics, 50(2), 379–402. DOI:

Pacheco, J., & Sykes, L. (1992). Seismic moment catalog of large shallow earthquakes, 1900 to 1989. Bulletin of the Seismological Society of America, 82(3), 1306–1349. DOI:

Papanikolaou, D., Alexandri, M., and Nomikou, P. (2006). Active faulting in the north Aegean basin. Geological Society of America. DOI:

Papazachos, B., & Comninakis, P. (1971). Geophysical and tectonic features of the Aegean Arc. Journal of Geophysical Research, 76(35), 8517–8533. DOI:

Papazachos, B., Papadimitriou, E., Kiratzi, A., Papazachos, C., & Louvari, E. (1998). Fault plane solutions in the Aegean Sea and the surrounding area and their tectonic implication. Bollettino Di Geofisica Teorica Ed Applicata, 39, 199–218.

Papazachos, B., & Papazachou, C. (2003). The earthquakes of Greece. Ziti Publ. Co.

Papazachos, C., & Kiratzi, A. (1996). A detailed study of the active crustal deformation in the Aegean and surrounding area. Tectonophysics, 253(1–2), 129–153. DOI:

Rocca, A., Karakaisis, G., Karacostas, B., Kiratzi, A., Scordilis, E., & Papazachos, B. (1985). Further Evidence on the Strike-slip Faulting of the Northern Aegean Trough Based on Properties of the August–November 1983 Seismic Sequence. Bolletino Di Geofisica Teorica Ed Applicata, XXVII(106), 101–109.

Rodriguez, M., Sakellariou, D., Gorini, C., Janin, A., D’Acremont, E., Pourhiet, L., Chamot-Rooke, N., Tsampouraki-Kraounaki, K., Morfis, I., Rousakis, G., Henry, P., Lurin, A., Delescluse, M., Briole, P., Rigo, A., Arsenikos, S., Bulois, C., Fernández-Blanco, D., Beniest, A., Grall, C., Chanier, F., Caroir, F., Dessa, J.X., Oregioni, D., & Nercessian, A. (2023). Evolution of the North Anatolian Fault from a diffuse to a localized shear zone in the North Aegean Sea during the Plio-Pleistocene. Geophysical Journal International, 235(3), 2614–2639. DOI:

Sakellariou, D., Rousakis, G., Vougioukalakis, G., Ioakim, C., Panagiotopoulos, I., Morfis, I., Zimianitis, E., Athanasoulis, K., Tsampouraki-Kraounaki, K., & Mpardis, D. (2017). DEFORMATION PATTERN IN THE WESTERN NORTH AEGEAN TROUGH: PRELIMINARY RESULTS. Bulletin of the Geological Society of Greece, 50(1), 124. DOI:

Thingbaijam, K., Martin Mai, P., & Goda, K. (2017). New empirical earthquake source-scaling laws. Bulletin of the Seismological Society of America, 107(5), 2225–2246. DOI:

Utsu, T. (1961). A Statistical Study on the Occurrence of Aftershocks. The Geophysical Magazine, 30, 521–605.

Wadati, K. (1933). On the Travel Time of Earthquake Waves. Geophysical Magazine, 7, 101–111.

Waldhauser, F. (2001). hypoDD-A Program to Compute Double-Difference Hypocenter Locations. DOI:

Waldhauser, F., & Ellsworth, W. (2000). A Double-Difference Earthquake Location Algorithm: Method and Application to the Northern Hayward Fault, California. Bulletin of the Seismological Society of America, 90(6), 1353–1368. DOI:

Wang, R. (1999). A simple orthonormalization method for stable and efficient computation of Green’s functions. Bulletin of the Seismological Society of America, 89(3), 733–741. DOI:

Wells, D., & Coppersmith, K. (1994). New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement. Bulletin of the Seismological Society of America, 84(4), 974–1002. DOI:

Wessel, P., Smith, W., Scharroo, R., Luis, J., & Wobbe, F. (2013). Generic mapping tools: improved version released. Eos, Transactions American Geophysical Union, 94(45), 409–410. DOI:

Wiemer, S., & Wyss, M. (2000). Minimum Magnitude of Completeness in Earthquake Catalogs: Examples from Alaska, the Western United States, and Japan. Bulletin of the Seismological Society of America, 90(4), 859–869. DOI:



How to Cite

Bonatis, P., Karakostas, V., Kourouklas, C., Kostoglou, A., & Papadimitriou, E. (2024). Spatiotemporal characteristics and earthquake statistics of the 2020 and 2022 adjacent earthquake sequences in North Aegean Sea (Greece). Seismica, 3(1).