Geology, geomorphology and geochronology of the coseismic? Emad Deh rock avalanche associated with a growing anticline and a rising salt diapir, Zagros Mountains, Iran

This work documents for the first time prehistoric, but morphologically pristine, Emad Deh rock avalanche of Zagros Mountains. The ca. 420 Mm 3 was initiated as a rockslide on dip slope affecting weak unit marls with interbedded limestones overlain by thick and competent limestone formation. is located northern limb growing Gavbast Anticline at edge inflating Dome, related to buried salt diapir Hormuz salt. unconfined deposits, covering 32 km 2 , were accumulated coalescing alluvial fans floodplain environment. depositional lobe shows sectors distinctive morphological features attributable variable flow-depositional behavior debris stream, controlled nature substrate: (1) proximal continuous breccia flanked levees; (2) intermediate depression; (3) flat-topped polygonal hills conical hills. A morphometric spatial distribution analysis has been performed 550 (hummocks) mapped in distal sector. avalanche, 914 m maximal height drop (H) 9280 runout (L), displays an extraordinarily high mobility (H/L index 0.09), that can be attributed combined effect dynamic fragmentation basal lubrication soft substrate floodplain. Relief rejuvenation over-steepening growth anticline inflation Dome are considered main long-term preparatory factors shifted state marginal stability. failure likely triggered large M ? 6.5–7 earthquake 5.4 ka, indicated OSL ages obtained from folded alluvium situated just beneath deposit. source probably blind reverse fault asymmetric Anticline, support structural geomorphic fold. identification dating coseismic landslides Mountains, where earthquakes rarely accompanied primary surface ruptures, could help improve both landslide seismic hazard assessments. • potentially ka Slope associated Changes flow morphology Morphometric hummocks Tectonic geomorphology allows inferring potential seismogenic source.