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

368 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E PATA Days 2024 K E Y W O R D S 2008 Nura earthquake, surface rupture, f lexural-slip faulting, Pamir-Tien Shan (1) Institute of Geoscience, University of Potsdam, Potsdam-Golm, Germany. (12) Institute of Seismology, National Academy of Science of Kyrgyzstan, Bishkek, Kyrgyzstan (3) School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA (4) Institute of Earth and Environmental Sciences, University of Freiburg, Freiburg, Germany (5) NAGRA, Wettingen, Switzerland *Email: patyniak@uni-potsdam.de M. Patyniak (1) A. Dzhumabaeva (2) S. Baikulov (2) A. M. Williams (3) F. Preusser (4) A. Landgraf (5) K. E. Abdrakhmatov (2) J R. Arrowsmith (3) M. R. Strecker (1) THE SURFACE RUPTURE OF THE 2008 MW 6.6 NURA EARTHQUAKE: UNCOVERING SECONDARY, FLEXURAL-SLIP SURFACE RUPTURE IN THE TIEN SHAN-PAMIR COLLISION ZONE, SOUTH KYRGYZSTAN A B S T R A C T This study explores the relationship between earthquake sources and seismogenic surface rupture in the collision zone of the Southern Tien Shan and Northern Pamir ranges in Central Asia. We focus on the 2008 Mw 6.6 Nura earthquake along the Pamir Frontal Thrust, that triggered a surface rupture in the footwall 10 km away from the presumed source fault. Using structure-from-motion, we integrate field-based tectono-geomorphic observations and detailed fault-zone mapping to understand the complexities of faulting mechanics and subsurface structures influencing surface deformation. Findings suggest slip along deep-seated basement faults triggered flexural slip in folded Cenozoic units, causing surface rupture in Quaternary glacial deposits. We infer a recurrence interval of 1.7 kyr and a Holocene vertical offset rate of 0.4 mm/yr. The study emphasizes the importance of considering indistinct linkages between surface and subsurface structures in seismic hazard assessments. This on-site investigation contributes to understanding the regional fault system, highlighting the complexities of earthquake ruptures and urging caution against underestimating seismic effects in poorly defined rupture areas. I N T R O D U C T I O N This research focuses on understanding the origins of destructive earthquakes in complex tectonic settings, such as fold-and-thrust belts and collisional zones. Particularly challenging are cases where seismic events exhibit subtle surface