Seismic Swarm Near Bulanık, Turkey: February 2011
An earthquake swarm designated S20110222.2 was recorded 11 km south-southeast of Bulanık in Muş Province, eastern Turkey. The sequence began at 06:36 on 22 February 2011 and concluded at 01:13 on 28 February 2011, spanning 138 hours and 36 minutes. A total of 115 events were registered during this interval. Analysis of the first 100 events shows a rapid onset with an initial magnitude 4.1 earthquake at 10 km depth. Subsequent activity included multiple events in the 2.5–4.6 range, with the largest reaching magnitude 4.6 at 5 km depth. Focal depths clustered between 2 km and 20 km, consistent with shallow crustal faulting. Event frequency peaked in the first 24 hours before gradually declining. The Bulanık region occupies the Eastern Anatolian Plateau, where ongoing convergence between the Arabian and Eurasian plates drives distributed deformation. This tectonic regime produces a network of strike-slip and thrust faults that accommodate north-south shortening and eastward extrusion of Anatolian crust. Seismic activity is further modulated by the nearby East Anatolian Fault system and regional volcanic features associated with the plateau’s uplift history. Eastern Turkey has a well-documented record of destructive earthquakes linked to these plate-boundary processes. Notable historical events include the 1966 Varto earthquake and earlier shocks that affected the Muş and Van basins. The 2011 swarm occurred within this established seismic belt but remained moderate in scale. The observed swarm characteristics—high event rate, shallow depths, and absence of a single dominant mainshock—align with fluid-driven or stress-transfer mechanisms commonly reported in the Anatolian collision zone. No surface rupture or significant damage was associated with the sequence.
References
SeismoSight internal classification records
USGS Earthquake Catalog (ANSS Comprehensive Catalog)
AFAD National Earthquake Database, Republic of Turkey
Active tectonics of the Eastern Anatolian Plateau, Journal of Geophysical Research (updated regional syntheses)