Landslides are the main secondary effects of earthquakes in mountainous areas. The spatial distribution of these landslides is controlled by the seismic ground motion and the local slope stability. While gravitational instabilities in arid and semi-arid environments are understudied, we document the landslides triggered by the Sarpol-Zahab earthquake (November 12, 2017, Mw7.3, Iran/Iraq border), the largest event ever recorded in the semi-arid Zagros Mountains. An original earthquake-induced landslide inventory was derived, encompassing landslides of various sizes and velocities (from rapid disrupted rockfalls to slow-moving coherent landslides). This inventory confirms the low level of triggered landslides in semi-arid environments. It also displays clear differences in the spatial and volumetric distributions of earthquake-induced landslides, having a 386 rockfalls of limited size triggered around the epicenter, and 9 giant (areas of ca. 10 6 m 2 ) active and ancient rockslides coseismically accelerated at locations up to 180 km from the epicenter. This unusual distant triggering is discussed and interpreted as an interaction between the earthquake source properties and the local geological conditions, emphasizing the key role of seismic ground motion variability at short spatial scales in triggering landslides. Finally, the study documents the kinematics of slow-moving ancient landslides accelerated by earthquakes, and opens up new perspectives for studying landslide triggering over different time-scales.shaking, generating fewer shallow disrupted slides in soils and colluvial deposits, which usually predominate during earthquakes in wet conditions (Harp and Jibson, 1995;Keefer, 2002). Arid and semi-arid regions are, however, of great interest for the study of factors controlling earthquake-triggered landslides, because the interfering effect of rainfall occurs little or not at all and site effects should be limited.This study analyzes the distribution of landslides triggered by the Sarpol-Zahab earthquake (Mw7.3, Iran) that occurred on November 12th 2017 in the semi-arid (mean precipitation of 230 mm/yr) northwest region of the Zagros Mountains (Fig. 1). This major earthquake, associated with the rupture of a low angle blind thrust fault at depths of 15-20 km (Gombert et al., 2019), occurred at the end of the dry season in an area that encompasses many giant paleo-landslides, of volumes up to 30 km 3 (Ghazipour and Simpson, 2016). Following this earthquake, a few coseismic landslides of various types (debris fall, boulder/rock fall) were reported near the epicenter (Miyajima et al., 2018;Vajedian et al., 2018). The earthquake also reactivated the giant Mela-Kabod landslide (4-km-long, 1-km-wide) located ~40 km south of the epicenter (Vajedian et al., 2018;Goorabi, 2020). To our knowledge, no reactivation was reported at other giant landslides mapped by Ghazipour and Simpson (2016) in the region.Accordingly, this study, which is based on an exhaustive inventory of the induced landslides, aims at understanding ...
