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The unlocking process of the 2016 Central Italy seismic sequence
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  • Monica Sugan,
  • Stefano Campanella,
  • Maddalena Michele,
  • Lauro Chiaraluce,
  • Alessandro Vuan
Monica Sugan
OGS - Istituto Nazionale di Oceanografia e di Geofisica Sperimentale

Corresponding Author:[email protected]

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Stefano Campanella
National Institute of Oceanography and Applied Geophysics - OGS
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Maddalena Michele
Istituto Nazionale di Geofisica e Vulcanologia
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Lauro Chiaraluce
Istituto Nazionale di Geofisica e Vulcanologia
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Alessandro Vuan
National Institute of Oceanography and Applied Geophysics - OGS
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Abstract

Approximately 23,000 well-located earthquakes from 2009 to 2016 are used as templates to recover seismic activity preceding the 2016 Central Italy seismic sequence. The resulting spatiotemporal pattern is analyzed employing ~91,000 newly detected events. In the 8 years before the sequence onset, microseismicity (Ml minor or equal to 3.7) develops at the hangingwall of the 2016 fault system and along a sub-horizontal shear zone. The events, mainly organized in clusters, represented by foreshock-mainshock and swarm-like sequences, migrate toward the nucleation area of the first Mw 6.0 mainshock of the sequence that occurred on the 24th of August in Amatrice. We propose an unlocking model based on variable temporal clustering of the seismicity, including repeaters, identifying fault portions with different degree of coupling and rheology, responding differently to the tectonic loading, and working to progressively localize the deformation process, increasing rock damage and weakening the nucleation patch of the Amatrice mainshock.
16 Mar 2023Published in Geophysical Research Letters volume 50 issue 5. 10.1029/2022GL101838