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Far-field coseismic forcing of giant rockslides in the 2017 Sarpol-Zahab Earthquake (Iran)
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  • Aya Cheaib,
  • Pascal Lacroix,
  • Swann Zerathe,
  • Denis Jongmans,
  • najmeh ajorlou,
  • Marie-Pierre Doin,
  • James Hollingsworth,
  • Chadi Abdallah
Aya Cheaib
Université Grenoble Alpes

Corresponding Author:[email protected]

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Pascal Lacroix
ISTerre/IRD/UGA/CNRS
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Swann Zerathe
ISTerre
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Denis Jongmans
Grenoble University
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najmeh ajorlou
2Department of earth science, Institute for Advanced Studies in Basic Sciences(IASBS)
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Marie-Pierre Doin
Institut des Sciences de la Terre
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James Hollingsworth
Université Grenoble Alpes
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Chadi Abdallah
CNRS
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Abstract

On November 12th 2017, the largest earthquake (Mw 7.3) ever recorded in the Zagros mountains occurred near the town of Sarpol-Zahab, Iran. While this region encompasses clusters of giant ancient rockslides, this seismic event is an excellent case-study to decipher the controlling factors of earthquake-induced landslides. Here, we address this issue by deriving an original earthquake-induced landslide inventory, encompassing landslides of various velocities (from rapid rockfalls to slow-moving landslides). This inventory displays clear differences in the spatial and volumetric distributions of earthquake-induced landslides, with 360 rockfalls triggered around the epicenter, and 9 giant active and ancient rockslides coseismically accelerated at locations up to 180 km from the epicenter. This distant triggering is explained by the earthquake source properties coupled with the local geological conditions. Our study documents a rare example of slow-moving landslides accelerated by an earthquake, and opens perspectives for the study of the landslide triggering over various time-scales.