Seismic Swarm Activity in Western Turkey: October 2024 Event

Western Turkey occupies a highly active tectonic zone at the junction of the Anatolian, Eurasian, and African plates. The region experiences ongoing deformation driven by the North Anatolian Fault Zone to the north and extensional tectonics associated with Aegean back-arc spreading. These forces produce frequent shallow crustal earthquakes, typically at depths of 5–15 km, reflecting normal and strike-slip faulting within the upper crust.

The seismic swarm designated S20241027.1 began at 00:58 on 27 October 2024 and concluded at 02:08 on 28 October 2024, spanning 25 hours and 9 minutes. During this interval, 28 earthquakes were recorded. Magnitudes ranged from 0.9 to 3.5, with the largest event (M 3.5) occurring at 08:56 on 27 October at a depth of 12 km. Depths throughout the sequence remained shallow, predominantly between 4 km and 12 km, consistent with the regional crustal structure.

Event timing showed clustering in the first several hours, followed by a gradual decline. Early activity included multiple events near M 2.0–2.9 within the initial two hours, while later phases featured smaller magnitudes interspersed with occasional moderate events. Depths showed minor variation but stayed within the typical range for western Anatolian crust.

Historical records indicate limited swarm-type sequences in the area since 2000. Only one prior swarm has been identified, occurring in 2001. This rarity underscores the predominantly mainshock-aftershock character of regional seismicity rather than prolonged swarm behavior.

The October 2024 swarm did not exceed magnitude 4.0 and produced no reported damage. Such low-to-moderate sequences provide valuable data on background strain release within the Aegean extensional domain. Continued monitoring remains essential given the region’s capacity for larger events along major fault systems.

References

USGS Earthquake Catalog
EMSC Earthquake Database
Tectonic framework summaries from the Geological Society of London publications on Anatolian-Aegean tectonics