Turkey: Extreme Events in 2023
In February 2023, a pair of very strong earthquakes of magnitude M 7.8 and M 7.5 (USGS) struck an extensive fault system in Eastern Anatolia. These shocks were the strongest Turkey had experienced since 1939.1
The difference between the 1939 earthquake and this one, however, is that the 1939 earthquake was not a doublet. Such cases of very strong earthquakes occurring within hours are extremely rare, and the 2023 Turkey case belongs among the rarest and most extreme doublets known.
Moreover, the February 6, 2023 event in Turkey can be considered an exceptional multiple sequence of large earthquakes representing an extraordinarily rare “cascade” scenario in global seismology. Within approximately 9 hours, two main shocks with moment magnitudes M 7.8 (focal depth 8.6 km) and M 7.5 (focal depth 7 km) occurred, while an exceptionally strong aftershock with magnitude M 6.6 occurred between them.2 This aftershock, whose epicenter was located in the Nurdağı district in Gaziantep Province, exceeds the usual definition of an aftershock by its size and further underscores the exceptional nature of the entire sequence, since such a concentration of very strong earthquakes within such a short time interval is extremely rare on a global scale.
Another extraordinary aspect is that the rupture of this earthquake propagated along several segments and locally reached supershear velocity. Supershear earthquakes are extremely rare and belong among the most destructive rupture types. The energy is then released much more abruptly and causes significantly stronger shaking effects than ordinary earthquakes.3
Fig. 1: Number of earthquakes with M ≥ 4.5 in Turkey since 1980, data source: https://earthquake.usgs.gov/earthquakes/search/
Fig. 2: Analyzed zone in the Turkey region, image source: Google Earth, own modification
The graph in Figure 1 highlights the exceptional nature of the seismic sequence in eastern and southeastern Turkey in 2023 compared with historical strong earthquakes in the country. The subsequent aftershock activity was extraordinarily extensive—over the course of weeks and months more than 200 earthquakes with magnitude M 4.5+ were recorded, including dozens of shocks with magnitude M 5–M 6, while normally fewer than 25 such earthquakes occur annually in Turkey. Figure 2 shows the boundaries of the analyzed zone on the map.
Compared with other major Turkish earthquakes, such as the İzmit earthquake in August 1999 (M 7.6) followed by the Düzce earthquake in November 1999 (M 7.2), or the Van earthquake in October 2011 (M 7.2)4, the year 2023 represents a significant deviation. Although those events reached magnitudes greater than M 7 and had devastating consequences, their aftershock sequences had a more classical evolution with a substantially lower number of M 4.5+ shocks and a faster decline of activity. The 2023 seismic sequence thus suggests a complex, multi-segment rupture and cascading stress transfer along the East Anatolian Fault, making it one of the most unusual and energetic aftershock sequences recorded in Turkey in modern seismological history.
References:
United Nations Office for the Coordination of Humanitarian Affairs (2023) “Earthquake: Türkiye and north-west Syria.” Available at: https://www.rcce-collective.net/wp-content/documents-repo/Earthquake/Resources/Situation/EarthquakeGZT-FlashUpdate-FIN.pdf (Accessed: March 16, 2026).
Demir, A. et al. (2025) “Destructive impact of successive high magnitude earthquakes occurred in Türkiye’s Kahramanmaraş on February 6, 2023,” Bulletin of Earthquake Engineering, 23(3), pp. 893–919. Available at: https://doi.org/10.1007/s10518-024-01865-5.
Rosakis, A., Abdelmeguid, M. and Elbanna, A. (2023) “Evidence of Early Supershear Transition in the Mw 7.8 Kahramanmaraş Earthquake From Near-Field Records.” arXiv. Available at: https://doi.org/10.48550/arXiv.2302.07214.
Sahin, S. (2023) “Last 123 years' largest earthquakes in Türkiye”. Available at: https://www.aa.com.tr/en/turkiye/last-123-years-largest-earthquakes-in-turkiye/2836533 (Accessed: March 16, 2026).