Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

372 PATA Days 2024 Long-term behavior The 2008 Nura surface rupture aligns consistently with local topographic highs, particularly along the ridge crest or the northwest-facing limb of the fault- parallel fold in Paleogene sedimentary rocks. These topographic highs, associated with ponding, abandoned streams, and deflected channels, likely represent cumulative tectonic landforms from earlier ruptures. To understand their history, the regional tectonic setting of the Nura area needs consideration, along with determining the onset of faulting and deformation rates. The Nura area exhibits complete closure of the topographic depression between the Pamir and Tien Shan, leading to deformation, uplift, and exposure of Paleozoic to Cenozoic units. The history of uplift is evident in the drainage divide between the present- day Kyzylsu rivers, formed during the late Cenozoic. The Nura River course, cutting through valley moraines, was influenced by the IrkF activity and uplift during basin closure. Geochronological data from the Nura site provides age estimates for tectonic landforms associated with the 2008 rupture. Luminescence dates suggest a minimum age of 11.3 ± 0.5 kyr for moraine deposits within the rupture zone and an age of 12.0 ± 0.6 kyr for paleo-lake sediments associated with landslides emerging from an open Paleogene syncline north of Nura settlement. These ages imply a 12 kyr period of IrkF-related relief growth, resulting in a maximum Holocene offset rate of 0.4 mm/yr considering up to 5 m high tectonic landforms. The distribution of displacements in 2008 correlates with cumulative patterns, indicating past earthquakes in the regional fault system triggering similar ruptures. The cumulative vertical separation divided by the 2008 one suggests approximately seven earthquakes akin to the 2008 Nura event, occurring at minimum intervals of 1.7 kyr, were needed to generate the present fault-zone morphology. These estimates align with the estimated 1.9 kyr recurrence interval along the central segment of the PFT (Patyniak et al., 2021). Nevertheless, caution is warranted due to limited geochronological data, emphasizing the need for further paleoseismic investigations along the fault zone to validate these findings. C O N C L U S I O N This study conducted a comprehensive analysis of the 2008 Mw 6.6 Nura earthquake rupture zone in the Northern Pamir region, Central Asia. Our primary goal was to understand seismogenic structures and their impact on tectono-gemorphic fault-zone characteristics. Building upon existing seismic fault models, we identified flexural-slip faulting as the primary mechanism for the observed surface rupture. The study revealed intricate influences on surface deformation, including variations in till thickness and geological conditions. The study contributes new information to the Worldwide and Unified Database of Surface Ruptures (SURE) (Baize et al., 2019; Nurminen et al., 2022), classifying the rupture as a triggered distributed and flexural-slip event. Our findings provide valuable insights into the Nura fault model, fault displacement, and hazard assessment, emphasizing the complexities of seismogenic flexural- slip faulting and the ongoing need for research in understanding remotely triggered faults. A C K N O W L E D G E M E N T S This project is a component of the CaTeNA initiative under the Client II program, funded by the German Federal Ministry of Education and Research (BMBF) through Sub-project grant 03G0878E to M. Strecker. Our on-site research received generous assistance from the Institute of Seismology at the National Academy of Science of Kyrgyzstan (located in Bishkek, Kyrgyzstan). The authors express gratitude to Jon Mosar at the University of Fribourg, Switzerland, for engaging discussions on regional tectonics, which significantly contributed to enhancing our geostructural interpretations.