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

310 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 Paleoseismology, neotectonics, tectonic geomorphology, earthquakes (1) Department of Earth Science, University of Oxford, neill. (2) Azerbaijan National Academy of Science, Baku, Azerbaijan, (3) Department of Geography, University of Sheffield, Sheffield (4) Department of Earth, Planetary, and Space Sciences, University of California Los Angeles, Los Angeles (5) School of Engineering and Natural Sciences, University of Iceland, Reykjavík, Iceland *Email: marshall@earth.ox.ac.uk / sabina.k@mail.ru / ed.rhodes@ sheffield.ac.uk / gregoryp@hi.is Neill Marshall (1) Sabina Kazimova (2 ) Ilyas Kazimova (2) Ian Pierce (1) Ben Johnson (1 ) Richard Walker (1) Ed Rhodes (3,4) Gregory De Pascale (5) PALEOSEISMOLOGY OF WEST CASPIAN FAULT (AZERBAIJAN) AND ACTIVE FAULTING IN AN OVER- PRESSURED SEDIMENTARY BASIN A B S T R A C T We provide the first geomorphic evidence for active dextral strike-slip faulting at the eastern margins of the Greater Caucasus and western margin of the South Caspian Basin. The West Caspian Fault is one of several parallel strands and showing numerous right- lateral stream deflections and follows mud volcano alignments. Mud volcanoes occur predominantly at bends along the strike-slip trace, indicating structural controls on emplacement. Mud volcano distribution and alignments in seismicity allow us to infer a total fault length of ~150 km. We estimate a minimum slip- rate of 3.9- 4.8 mm/yr averaged over the Holocene, based upon a displaced terrace riser of assumed age. Two paleoseismic trenches reveal between four and six surface rupture events over the last 3000 years, a seventh prior to that, and an average recurrence interval of 500-750 years. The events are unevenly spaced in time, with a significant cluster of 2 or 3 events in the last 600 years, and much longer intervals earlier. From earthquake scaling relationships we would expect rupture of the entire fault length to produce Mw 7.5 events with average slip of 3 m, which is consistent with the smaller lateral offsets (2-3 m). However, a lack of historical earthquakes combined with inferences on fault behaviour within the fluid- rich Kura basin sediments lead us to speculate that the ruptures may represent either aseismic slip events or low magnitude surface rupturing events. I N T R O D U C T I O N The West Caspian Fault zone forms part of a triple junction between the Greater Caucasus Mountains and South Caspian

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