loading page

The 2019-2020 Khalili (Iran) earthquake sequence - anthropogenic seismicity in the Zagros Simply Folded Belt?
  • +6
  • Mohammadreza Jamalreyhani,
  • Léa Pousse‐Beltran,
  • Pınar Büyükakpınar,
  • Simone Cesca,
  • Edwin Nissen,
  • Abdolreza Ghods,
  • José Ángel López-Comino,
  • Mahdi Rezapour,
  • Mahdi Najafi
Mohammadreza Jamalreyhani
Institute of Geophysics, University of Tehran, Iran- GFZ German research center for Geosciences, Potsdam, Germany

Corresponding Author:m.jamalreyhani@gmail.com

Author Profile
Léa Pousse‐Beltran
School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, UGE, ISTerre, 38000 Grenoble, France
Author Profile
Pınar Büyükakpınar
Kandilli Observatory and Earthquake Research Institute, Boğaziçi University, İstanbul, Turkey
Author Profile
Simone Cesca
GFZ German Research Centre for Geosciences
Author Profile
Edwin Nissen
University of Victoria
Author Profile
Abdolreza Ghods
Institute for Advanced Studies in Basic Sciences
Author Profile
José Ángel López-Comino
University of Granada
Author Profile
Mahdi Rezapour
Author Profile
Mahdi Najafi
Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
Author Profile


We investigate the origin of a long-lived earthquake cluster in the Fars arc of the Zagros Simply Folded Belt that is co-located with the major Shanul natural gas field near the small settlement of Khalili. The cluster emerged in January 2019 and initially comprised small events of w 5.4 and 5.7 earthquakes, which were followed by > 100 aftershocks. We assess the spatio-temporal evolution of the earthquake sequence using multiple event hypocenter relocations, waveform inversions, and Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) measurements and models. We find that the early part of the sequence is spatially distinct from the June 9, 2020 earthquakes and their aftershocks. Moment tensors, centroid depths, and source parameter uncertainties of fifteen of the largest (Mn ≥ 4.0) events show that the sequence is dominated by reverse faulting at shallow depths (mostly ≤ 4 km) within the sedimentary cover. InSAR modelling shows that the Mw 5.7 mainshock occurred at depths of 2–8 km, with a rupture length and maximum slip of ~20 km and ~0.5 m, respectively. Our results strongly suggest that the 2019-2020 Khalili earthquake sequence was influenced by the operation of the Shanul field, making these the first known examples of gas extraction anthropogenic earthquakes in Zagros. Understanding the genesis of such events to distinguish man-made seismicity from natural earthquakes is helpful for hazard and risk assessment, notably in Iran which is both seismically-active and rich in oil and gas reserves.
Dec 2021Published in Journal of Geophysical Research: Solid Earth volume 126 issue 12. 10.1029/2021JB022797