U-Th dating of carbonate veins in connection with active tectonics has recently been used as an attractive tool for constraining the absolute timing of late Quaternary crustal deformations. In this study, for the first time we correlate U-Th ages of travertine deposits in co-seismic fissures along the North Anatolian Fault Zone (NAFZ) with records of Paleoseismological studies supported by Historical Earthquake catalogued data. U-Th ages are assed in relation to the recurrence interval and the size and epicentre distance of major Holocene earthquakes. Our statistical evaluations on age correlations indicate that the carbonate vein precipitation is concentrated in eight different periods along the NAFZ. The periods are well correlated with historical earthquake records and with previous dating results of the nearby trench studies. At least six of the periods correspond to the earthquakes reported in the historical catalogues. The age correlations of carbonate precipitation intervals for the last millennium show a recurrence along the eastern NAFZ with a mode at 130–330 years that is consistent with a previously proposed paleoseismic recurrence interval of the fault. Recorded events in carbonate veins indicate a close-epicentre (<200 km) and high-intensity (>VI) paleo earthquakes. Our results suggest that co-seismic carbonate veins could be used to determine paleoseismic records as a supplementary tool to augment paleoseismological techniques. This tool has advantages over traditional paleoseismological methods for the understanding of long-term earthquake behaviour, particularly for prehistoric late Pleistocene events which cannot be dated easily by traditional paleoseismological methods.

In the easternmost segment of the North Anatolian Fault (NAF) zone there are discrepancies in earthquake characteristics arising from differences between geodetically determined and geologically observed slip rates. We investigated the spatial distribution of deformation across a NAF fault segment, Turkey. Field observations were conducted on the offset of physiographic features along the principle fault and on a carbonate-filled fissure system a few hundred meters away from the main slip zone. Considering the rheology of the geological units, we propose distributed deformation across the principal fault strand in a stretching zone causing sigmoidal simple-shear rotation of the carbonate-filled fissure system. Since the fissure system is made up by previously dated alternating carbonate bands formed during distinct rupture events, the sigmoidal deformation provides an opportunity to understand the off-fault deformation rate in the stretching zone. Comparing displacement data of the sigmoidal carbonate vein with isotopic age results indicates an off-fault deformation of 15.72±2.83 mm per year for the Holocene, which corresponds to at least 50% of the geodetically estimated annual slip across the fault. The results indicate that distributed deformation needs to be taken into account in terms of the discrepancies on earthquake characteristics of active fault systems.