Late Holocene slip rate for the North Anatolian fault, Turkey, from cosmogenic ³⁶Cl geochronology: Implications for the constancy of fault loading and strain release rates

Abstract

Geomorphologic mapping and cosmogenic radionuclide (³⁶Cl) dating of an offset fluvial terrace yield a preferred late Holocene slip rate of 20.5 ± 5.5 mm/yr for the central part of the North Anatolian fault, Turkey; an independent slip rate constrained by ¹⁴C ages is 20.5 ± 8.5 mm/yr. These rates are generally similar to, but possibly slightly slower than, the short-term rate of elastic strain storage of 25 ± 1 measured geodetically across this major strike-slip fault (Reilinger et al., 2006), suggesting that loading and strain release on this part of the North Anatolian fault have been relatively constant when averaged over the past ∼2–2.5 k.y. We attribute this consistency to the relatively simple structure of the Anatolia-Eurasia plate boundary in north-central Turkey, where almost all plate boundary strain is accommodated along the North Anatolian fault. The absence of other moderate to high slip rate faults (and the earthquakes they produce) leads to a relatively simple stress evolution for the fault dominated by steady tectonic loading.