Paleoseismic Evidence for Multiple Strand Ruptures Along the Amanos section of the East Anatolian Fault, Turkey

Sinan O. Akciz, Aynur Dikbas, Musa Balkaya, Angel Beltran, Andrew Azzam, & Muhammed Seyyid Demir

Submitted August 30, 2026, SCEC Contribution #15524, 2026 SCEC Annual Meeting Poster #TBD

On February 6, 2023, an Mw 7.8 earthquake ruptured ~300 km of the left-lateral East Anatolian Fault (EAF), followed ~9 hours later by an Mw 7.6 event on the Çardak Fault. The ~700 km-long EAF accommodates westward extrusion of the Anatolian microplate driven by Arabia–Eurasia collision. The Mw 7.8 rupture broke multiple sections—including the Amanos, Pazarcık, and Erkenek sections—within a recognized seismic gap, contrasting with a paleoseismic picture based on historical earthquakes interpreted to have ruptured these sections separately. Historical records suggest the Amanos Fault ruptured in 1872, 1407, and 1114 CE, and unpublished work farther north suggests an additional rupture in 1822, but no prior study has dated any of these events geochronologically.
This study reconstructs the earthquake history of the Amanos Fault at the Bestami site near Kırıkhan, where an earlier trench (T1) exposed evidence of two earthquakes and motivated four new trenches in 2024. Trench T2, a benched trench across the mapped main trace (which did not rupture in 2023), exposed evidence for three earthquakes. Trenches T4 and T5 crossed a previously unrecognized strand that did rupture in 2023, exposing multiple faults within a ~3 m-wide zone reaching the surface.
Radiocarbon dating of detrital charcoal (UC Irvine) shows the main trace (T2) last ruptured 1275–1762 CE, with a penultimate event at 3496–3047 BCE, indicating that neither the 1872 nor the 1822 earthquake ruptured this section. On the newly identified strand (T4), the penultimate event occurred after 1167–1231 CE, and an older event after 4253–3516 BCE; the older events may reflect joint rupture of both strands. These data suggest this strand may have ruptured during the 1407 event or the more recent 1822 event, echoing the 2023 pattern in which the main trace stayed quiet while a nearby strand ruptured—raising the possibility that the main trace is repeatedly bypassed during large earthquakes. Ages rely on detrital charcoal, some likely reworked, limiting precision; pIR-IRSL luminescence dating could tighten constraints or reveal erosion or non-deposition intervals. These findings show that fault strands may lack recognizable geomorphic expression, and that trenching reconnaissance is essential for confirming the absence, not just the presence, of faulting: had 2023 not occurred, there would have been no reason to discover this strand, which clearly recorded multiple past earthquakes.

Citation
Akciz, S. O., Dikbas, A., Balkaya, M., Beltran, A., Azzam, A., & Demir, M. (2026, 08). Paleoseismic Evidence for Multiple Strand Ruptures Along the Amanos section of the East Anatolian Fault, Turkey. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology