Abstract
•Bottom sediments of Lake Hazar (crossed by EAF) are used as a paleoseismic record.•A ∼190 yrs of earthquake recurrence is found over 3800 yrs and 65% of all sedimentary events are attributed to East Anatolian Fault.•Paleoseismic record occurs in bursts due to clustered earthquakes along the East Anatolian Fault Zone.•Aseismic motion partly impacts the seismic cycle of EAF like along the North Anatolian Fault.
The East Anatolian Fault (EAF) in Turkey is a major active left-lateral strike-slip fault that was seismically active during the 19th century but mostly quiet during the 20th century. Geodetic data suggests that the fault is creeping along its central part. Here we focus on its seismic history as recorded in the sediments of Lake Hazar in the central part of the EAF. Sediment cores were studied using X-ray imagery, magnetic susceptibility, grain-size, loss-on-ignition and X-ray fluorescence measurements. Recurring thin, coarse-grained sediment units identified as turbidites in all cores were deposited synchronously at two deep study sites. The turbidite ages are inferred combining radiocarbon and radionuclide (137Cs and 210Pb) dating in an Oxcal model. A mean recurrence interval of ∼190 yrs is obtained over 3800 yrs. Ages of the recent turbidites correspond to historical earthquakes reported to have occurred along the EAF Zone or to paleoruptures documented in trenches just northeast of Lake Hazar. The turbidites are inferred to be earthquake-triggered. Our record demonstrates that Lake Hazar has been repeatedly subjected to significant seismic shaking over the past 3800 yrs. The seismic sources are variable: ∼65% of all turbidites are associated with an EAF source. The seismic cycle of central EAF is thus only partly impacted by creep.