Middle Holocene Go<spacing diaeresis>ynük <spacing diaeresis> ynük landslide (NW Anatolia): Geomorphological frame, failure mechanism, and a large (Mw7.9) earthquake trigger from the North Anatolian Fault

Predicting the maximum size of unexpected large earthquakes is crucial for hazard mitigation. This study investigates the Go<spacing diaeresis>yn & uuml;k landslide in the eastern Marmara Region, Turkey, a region with a high risk of future large earthquakes. We analyze the geotechnical properties of the failed slope and the age of an associated tufa deposit to understand the landslide's timing and triggering mechanism. Uranium-Thorium (U-Th) and radiocarbon dating reveals tufa deposition occurred from the warm interstadial of Marine Isotope Stage 6 (MIS6) around 130,000 years until 5700 years BP. Morphological data indicate the landslide removed part of the tufa platform and accelerated erosion (0.8 cm/year) in the Yayla River. Back-analysis suggests a minimum peak ground acceleration (PGA) of 0.665 g was needed for the landslide to occur. Considering potential topographic amplification, we propose a large earthquake (Mw 7.8-7.9) on the North Anatolian Fault (NAF), located 20 km north, triggered the landslide. This event might also be responsible for the failure of a previously documented landslide dam in the fault zone. While limited, these findings combined with existing data suggest the possibility of multiple large (Mw 8) earthquakes on the western NAF with millennial recurrence intervals. This challenges the current maximum estimated magnitude (Mw 7.4) based on the limited 2500-year paleoseismological record.