Location:

Period:

9 Nov 2011 02:20:01 - 20 Nov 2011 04:31:45 (11 days 2 hours 11 minutes)

Volcanoes in 100km radius:

Tenduruk Dagi(56km)

Earthquakes:

333

9 swarms found nearby.

2011

PS20111023.1(52.8km)

23 Oct

1 day 4 hours

10 earthquakes

S20111023.2(24.3km)

23 Oct

14 days 17 hours

739 earthquakes

S20111023.3(25.9km)

23 Oct

12 days 16 hours

415 earthquakes

S20111024.1(7.7km)

23 Oct

4 days 0 hours

78 earthquakes

S20111029.1(25.5km)

28 Oct

8 days 13 hours

155 earthquakes

S20111107.2(21.7km)

6 Nov

3 days 18 hours

79 earthquakes

S20111115.1(26.5km)

14 Nov

5 days 0 hours

63 earthquakes

S20111129.1(11.0km)

28 Nov

35 days 13 hours

454 earthquakes

2022

S20220613.1(10.9km)

12 Jun

3 days 2 hours

44 earthquakes

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Seismic Swarm S20111109.1 in Eastern Turkey: November 2011

Eastern Turkey lies within a complex tectonic regime at the convergence of the Arabian, Eurasian, and African plates. The region features the East Anatolian Fault Zone, the Bitlis-Zagros suture, and associated thrust systems that accommodate ongoing continental collision. These structures produce frequent shallow crustal earthquakes, with historical records documenting destructive events such as the 2011 Van earthquake sequence.

SeismoSight internal classification identifies Swarm S20111109.1 as the first of six swarms recorded in the area since 1 January 2000. The swarm initiated at 02:20 UTC on 9 November 2011 and concluded at 04:31 UTC on 20 November 2011, spanning 266 hours and 11 minutes. A total of 333 earthquakes were registered during this period.

Analysis of the first 100 events reveals predominantly shallow focal depths, with the majority occurring between 2 km and 10 km. A smaller subset reached depths of 15–24 km. Magnitudes ranged from 1.9 to 5.6, with the largest event (M 5.6) occurring at 19:23 UTC on 9 November at 5 km depth. Subsequent events included multiple shocks above M 4.5 within the first 24 hours, followed by a rapid decline into lower-magnitude activity. The sequence exhibited typical swarm characteristics: a high rate of small events clustered in both space and time without a single dominant mainshock-aftershock pattern.

Geological context indicates that the swarm occurred within the seismically active Eastern Anatolian plateau, where distributed deformation along secondary faults can generate such episodic clusters. Depths concentrated near 5–7 km align with the brittle upper crust in this tectonic setting.

The swarm underscores the persistent seismic hazard in Eastern Turkey. Continued monitoring of similar clusters remains essential for understanding strain release along the regional fault network.

References

SeismoSight internal swarm classification records
USGS Earthquake Catalog (historical Eastern Turkey events)
Turkish Disaster and Emergency Management Authority (AFAD) regional seismicity reports