Deltas contain sedimentary records that are not only indicative of water-level changes, but also particularly sensitive to earthquake shaking typically resulting in soft-sediment-deformation structures. The Kürk lacustrine delta lies at the south-western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re-evaluates water-level changes and earthquake shaking that have affected the Kürk Delta, combining geophysical data (seismic-reflection profiles and side-scan sonar), remote sensing images, historical data, onland outcrops and offshore coring. The history of water-level changes provides a temporal framework for the depositional record. In addition to the common soft-sediment deformation documented previously, onland outcrops reveal a record of deformation (fracturing, tilt and clastic dykes) linked to large earthquake-induced liquefactions and lateral spreading. The recurrent liquefaction structures can be used to obtain a palaeoseismological record. Five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the East Anatolian Fault. Sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator. Based on radionuclide dating (Cs and Pb), two major sedimentary events were attributed to the ad 1874 to 1875 East Anatolian Fault earthquake sequence. Their sedimentological characteristics were determined by X-ray imagery, X-ray diffraction, loss-on-ignition, grain-size distribution and geophysical measurements. The events are interpreted to be hyperpycnal deposits linked to post-seismic sediment reworking of earthquake-triggered landslides.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was carried out in the frame of the Marie Curie Excellence Grant Project ‘Understanding the irregularity of seismic cycles: A case study in Turkey’ (MEXT-CT-2005-025617: Seismic Cycles) centred at the Seismology Section of the Royal Observatory of Belgium whom we would like to thank for their support. We are grateful for the assistance of Prof. Erhan Altunel of Osmangazi University. The seismic lines were retrieved thanks to a fruitful collaboration with EMCOL (Eastern Mediterranean Centre for Oceanography and Limnology) and in particular Emre Damci. Logging in the field was done with the expertise of Jeff Fraser. We are indebted to X. Boes for his work during coring and on the cores: he acquired parts of the geophysical and geochronological data during his stay at the University of Rhode Island. Masters student Jean-Philippe Bouancheau also worked on core H005 for his thesis. PhD student Laura Lamair helped with the figures. The original manuscript was significantly improved thanks to the constructive reviews of Erhan Altunel, Katrin Monecke and the Associate Editor Vern Manville.