The 2011 Van Earthquake: Seismic Event and Regional Geology

On October 23, 2011, at 10:41 local time, a magnitude 7.1 earthquake struck 27 km north-northeast of Van, Turkey, at a focal depth of 18 km. This event represents the sole strong earthquake recorded in the region since January 1, 2000. Eastern Anatolia lies within a complex tectonic regime shaped by the ongoing collision between the Arabian and Eurasian plates. This convergence, occurring at rates of approximately 2–3 cm per year, has produced the Bitlis-Zagros suture zone and associated thrust systems. The Van region sits near the Van Fault, a north-dipping reverse structure capable of generating significant seismic events through compressional stress accumulation. The 2011 mainshock resulted from thrust faulting consistent with the regional stress field. Shallow crustal depths in this area amplify ground shaking, contributing to widespread structural damage across Van Province. Historical records indicate recurrent seismicity along the Eastern Anatolian fault systems, with notable predecessors including events in the 19th and early 20th centuries that followed similar thrust mechanisms. Post-event monitoring revealed an extensive aftershock sequence distributed along the fault plane, underscoring the potential for prolonged seismic activity following major ruptures in compressional settings. The interplay of regional tectonics and local fault geometry continues to define the seismic hazard for eastern Turkey.

References

USGS Earthquake Catalog Tectonic summaries of the Arabia-Eurasia collision zone