Distributed surface rupturing: there is a crack in everything – that’s
how the light gets in
Abstract
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.