Earthquake Swarm S20241028.1 in Central Turkey: Seismic Activity and Tectonic Context

Central Turkey occupies a key position within the Anatolian tectonic plate, a region shaped by the ongoing convergence of the Arabian, African, and Eurasian plates. This interaction drives the westward extrusion of Anatolia, accommodated primarily by major strike-slip fault systems. The North Anatolian Fault Zone bounds the area to the north, while the East Anatolian Fault Zone influences deformation farther east, with additional distributed faulting across central Anatolia contributing to moderate seismicity. Shallow crustal earthquakes are common due to the plate's relatively thin lithosphere and active fault networks.

The swarm S20241028.1 was recorded in this setting, beginning at 17:07 on 27 October 2024 and concluding at 15:50 on 28 October 2024. Over 22 hours and 43 minutes, 29 earthquakes were detected, with magnitudes ranging from 1.1 to 4.9 and focal depths between 1 and 11 km. The sequence initiated with a magnitude 4.9 event at 10 km depth, followed by numerous smaller events that clustered in time without a dominant mainshock-aftershock pattern. Notable later activity included a magnitude 3.4 event at 11 km depth on 28 October. Depths remained predominantly shallow, consistent with upper-crustal faulting typical of central Anatolian seismicity.

Earthquake swarms in this region often reflect transient stress perturbations, possibly linked to fluid migration or aseismic slip along existing faults. Historical records since 2000 indicate only three such swarms in central Turkey, occurring in 2010, 2023, and the current 2024 episode. These infrequent clusters underscore the region's baseline of distributed, low-to-moderate seismicity rather than frequent swarm activity.

The 2024 swarm's temporal evolution shows an initial energetic phase on 27 October with several events above magnitude 2.0, transitioning to lower-magnitude activity overnight and a modest resurgence on 28 October. Depths averaged around 6 km, suggesting activation within the brittle upper crust. Such patterns align with the broader tectonic regime where strain accumulates along secondary faults away from the primary plate-boundary zones.

Monitoring of these events provides valuable data on local stress fields and potential precursors to larger tectonic releases. Continued observation remains essential given Anatolia's history of destructive earthquakes driven by plate-boundary dynamics.

References

• United States Geological Survey (USGS) Earthquake Hazards Program: tectonic framework of the Anatolian Plate.
• SeismoSight internal classification for swarm parameters and event catalog.