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The 2015–2017 Pamir Earthquake Sequence: Fore-, Main-, and Aftershocks, Seismotectonics, Fault Interaction, and Fluid Processes
  • +7
  • Wasja Bloch,
  • Sabrina Metzger,
  • Bernd Dieter Schurr,
  • Xiaohui Yuan,
  • Lothar Ratschbacher,
  • Sanaa Reuter,
  • Qiang Xu,
  • Junmeng Zhao,
  • Shohrukh Murodkulov,
  • Ilhomjon Oimuhammadzoda
Wasja Bloch
Geoforschungszentrum Potsdam, Geoforschungszentrum Potsdam, Geoforschungszentrum Potsdam

Corresponding Author:[email protected]

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Sabrina Metzger
Helmholtz-Zentrum, Deutsches GeoForschungsZentrum Potsdam, Helmholtz-Zentrum, Deutsches GeoForschungsZentrum Potsdam, Helmholtz-Zentrum, Deutsches GeoForschungsZentrum Potsdam
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Bernd Dieter Schurr
Deutsches GeoForschungsZentrum GFZ, Deutsches GeoForschungsZentrum GFZ, Deutsches GeoForschungsZentrum GFZ
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Xiaohui Yuan
Deutsches GeoForschungsZentrum GFZ, Deutsches GeoForschungsZentrum GFZ, Deutsches GeoForschungsZentrum GFZ
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Lothar Ratschbacher
Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany, Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany, Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany
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Sanaa Reuter
Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany, Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany, Geologie, Technische Universität Bergakademie Freiberg, 09599 Freiberg, Germany
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Qiang Xu
Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Chinese Academy of Sciences
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Junmeng Zhao
Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Chinese Academy of Sciences
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Shohrukh Murodkulov
Institute of Geology, Earthquake Engineering and Seismology of the Academy Science of the Republic of Tajikistan, Institute of Geology, Earthquake Engineering and Seismology of the Academy Science of the Republic of Tajikistan, Institute of Geology, Earthquake Engineering and Seismology of the Academy Science of the Republic of Tajikistan
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Ilhomjon Oimuhammadzoda
Tajikistan Academy of Sciences, Tajikistan Academy of Sciences, Tajikistan Academy of Sciences
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Abstract

A sequence of three strong (M W 7.2, 6.4, 6.6) earthquakes struck the Pamir of Central Asia in 2015–2017. With a local seismic network, we recorded the succession of the fore-, main-, and aftershock sequences at local distances with good azimuthal coverage. We located 11,784 seismic events and determined 33 earthquake moment tensors. The seismicity delineates the tectonic structures of the Pamir in unprecedented detail, i.e., the thrusts that absorb shortening along the Pamir’s thrust front, and the strike-slip and normal faults that dissect the Pamir Plateau into a westward extruding block and a northward advancing block. Ruptures on the kinematically dissimilar faults were activated subsequently from the initial M W 7.2 Sarez event at times and distances that follow a diffusion equation. All mainshock areas but the initial one exhibited foreshock activity, which was not modulated by the occurrence of the earlier earthquakes. Modeling of the static Coulomb stress changes indicates that aftershock triggering occurred over distances of ≤90 km on favorably oriented faults. The third event in the sequence, the M W 6.6 Muji earthquake, ruptured despite its repeated stabilization through stress transfer in the order of -10 kPa. To explain the accumulation of M W > 6 earthquakes, we reason that the initial mainshock may have increased nearby fault permeability, and facilitated fluid migration into the mature fault zones, eventually triggering the later large earthquakes.
30 Nov 2022Published in Geophysical Journal International. 10.1093/gji/ggac473