Location:

Period:

28 Nov 2011 14:10:35 - 3 Jan 2012 03:35:06 (35 days 13 hours 24 minutes)

Volcanoes in 100km radius:

Tenduruk Dagi(64km)

Earthquakes:

454

M 7.0+:

M 7.1; 27 km NNE of Van, Turkey; (23 Oct 2011) (14km from the swarm center)

10 swarms found nearby.

2011

PS20111023.1(41.8km)

23 Oct

1 day 4 hours

10 earthquakes

S20111023.2(15.2km)

23 Oct

14 days 17 hours

739 earthquakes

S20111023.3(22.2km)

23 Oct

12 days 16 hours

415 earthquakes

S20111024.1(15.5km)

23 Oct

4 days 0 hours

78 earthquakes

S20111029.1(15.1km)

28 Oct

8 days 13 hours

155 earthquakes

S20111030.1(24.7km)

29 Oct

2 days 2 hours

46 earthquakes

S20111107.2(19.0km)

6 Nov

3 days 18 hours

79 earthquakes

S20111109.1(11.0km)

9 Nov

11 days 2 hours

333 earthquakes

S20111115.1(18.5km)

14 Nov

5 days 0 hours

63 earthquakes

2022

S20220613.1(8.1km)

12 Jun

3 days 2 hours

44 earthquakes

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Seismic Swarm S20111129.1: Analysis of Eastern Turkey Activity

Seismic swarm S20111129.1 occurred in eastern Turkey, beginning at 14:10 on 28 November 2011 and concluding at 03:35 on 3 January 2012. Over 853 hours and 24 minutes, the sequence recorded 454 earthquakes. This event followed the magnitude 7.1 Van earthquake of 23 October 2011, located 27 km north-northeast of Van and approximately 14 km from the swarm center.

Analysis of the initial events reveals a pattern of frequent, low-magnitude activity concentrated in the shallow crust. Magnitudes ranged primarily between 2.0 and 3.8, with the strongest events reaching 3.8 on 29 November and 30 November 2011. Depths clustered between 2 km and 24 km, with most occurring at or below 10 km, consistent with brittle failure in the upper crust. Temporal clustering showed elevated rates during the first week, particularly on 29 November and 30 November, before gradually declining. These characteristics align with typical swarm behavior driven by fluid migration or stress redistribution rather than a single mainshock-aftershock sequence.

Eastern Turkey occupies a tectonically complex zone within the Alpine-Himalayan orogenic belt. The ongoing convergence between the Arabian and Eurasian plates generates strike-slip and thrust faulting along the East Anatolian Fault Zone and related structures. This setting produces frequent moderate seismicity and occasional large events. Lake Van basin, near the swarm location, exhibits evidence of Quaternary volcanism and active extension superimposed on regional compression. Historical records document multiple destructive earthquakes in the Van region, underscoring long-term seismic hazard.

Since 2000, nine swarms have been documented in the area, with S20111129.1 representing the earliest recorded in this catalog. The proximity to the 2011 Van mainshock suggests possible triggering through static or dynamic stress changes, a mechanism observed in other post-mainshock swarms worldwide.

Further monitoring of such sequences contributes to improved understanding of fault interactions and seismic hazard assessment in convergent plate boundaries.

References

United States Geological Survey Earthquake Catalog
Kandilli Observatory and Earthquake Research Institute regional bulletins
Active Tectonics of the Eastern Mediterranean Region, Geological Society Special Publications