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Distributed surface rupturing: there is a crack in everything – that’s how the light gets in
  • Maria Francesca Ferrario,
  • Franz Livio,
  • Alessandro Michetti
Maria Francesca Ferrario
Universita dell'Insubria

Corresponding Author:[email protected]

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Franz Livio
Università dell'Insubria
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Alessandro Michetti
Universita dell'Insubria
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Strong (M 6 - 7) to large (M 7 – 8) earthquakes are capable to produce surface faulting both along the primary fault and distributed faults. The availability of modern technologies clearly highlighted the complexity of surface faulting associated with recent earthquakes worldwide, providing a dataset with unprecedented detail. Surface faulting and deformation pose a threat for critical facilities, lifelines and infrastructures; the assessment of the probability of occurrence of fault displacement is thus vital for risk mitigation and a proper planning. The recent datasets were not yet analyzed in this perspective, and current methodologies and scaling relations rely on data acquired few to tens of years ago. We perform a probabilistic fault displacement hazard analysis on distributed faulting due to modern earthquakes with normal and strike-slip kinematics. We show that current scaling relations tend to underpredict the actual occurrence of faulting, and we propose updated relations. Distributed faulting due to a large earthquake on one hand, and repeated ruptures at the same spot in a short time interval (e.g., Central Italy, 2016; Searles Valley and Ridgecrest 2019) on the other hand, are the end-members of a spectrum of surface faulting behavior. If not taken into account during the interpretation of paleoseismological data, different modes of fault rupture can significantly bias the derived earthquake parameters and, consequently, inferences on the regional tectonic activity.