Seismic Swarm in Central Turkey: Analysis of the August 2024 Event

A seismic swarm designated S20240823.1 was recorded in central Turkey between 06:30 on 23 August 2024 and 06:29 on 25 August 2024. Over 47 hours and 58 minutes, 48 earthquakes were detected. Magnitudes ranged from 0.9 to 3.9, with the largest event reaching 3.9 at a depth of 7 km. Depths were predominantly shallow, clustered around 7 km, though a few events extended to 16 km. Activity peaked in the afternoon of 23 August, featuring multiple events above magnitude 3.0 within a short interval, before gradually declining through 24 August and concluding early on 25 August.

The temporal distribution showed an initial burst of stronger shocks followed by lower-magnitude aftershocks. Most events occurred within the first 12 hours, illustrating the typical swarm pattern of clustered, non-mainshock-driven seismicity rather than a classic foreshock-aftershock sequence.

Central Turkey occupies a tectonically complex zone at the junction of the Anatolian, Eurasian, Arabian, and African plates. The region experiences ongoing deformation driven by the northward collision of the Arabian Plate with Eurasia, resulting in westward extrusion of the Anatolian Plate along major strike-slip systems. Prominent structures include segments of the North Anatolian Fault and distributed intraplate faults that accommodate regional strain. Shallow crustal earthquakes are common due to the brittle nature of the upper crust in this compressional regime.

Turkey maintains one of the highest levels of seismic hazard in the Mediterranean, with instrumental records documenting repeated destructive events throughout the twentieth and twenty-first centuries. The central sector, while less frequently highlighted than the eastern or western margins, has produced moderate-to-strong earthquakes linked to both mapped faults and previously unrecognized structures.

Since 1 January 2000, five swarms have been identified in the same area, occurring in 2010 (one swarm), 2023 (three swarms), and 2024 (this event). The recurrence indicates episodic swarm activity possibly associated with fluid migration or localized stress perturbations along minor fault networks.

Such swarms typically pose limited immediate risk of a large mainshock but can cause concern for local populations due to their prolonged duration and perceptible shaking. Continued monitoring remains essential for refining seismic hazard models in this rapidly deforming part of the Anatolian Plate.

References

• United States Geological Survey Earthquake Catalog (earthquake.usgs.gov)
• European-Mediterranean Seismological Centre (emsc-csem.org)
• Kandilli Observatory and Earthquake Research Institute, Boğaziçi University (koeri.boun.edu.tr)