Can large strains be accommodated by small faults: “Brittle flow of
rocks’ revised
Abstract
Brittle deformation in the upper crust is thought to occur primarily via
faulting. The fault length-frequency distribution determines how much
deformation is accommodated by numerous small faults vs a few large
ones. To evaluate the amount of deformation due to small faults, we
analyze the fault length distribution using high-quality fault maps
spanning a wide range of spatial scales from a laboratory sample to an
outcrop to a tectonic domain. We find that the cumulative fault length
distribution is well approximated by a power law with a negative
exponent close to 2. It follows that faulting is a self-similar process,
and a substantial fraction of tectonic strain can be accommodated by
faults that don’t cut through the entire brittle layer, consistent with
inferences of “hidden strain’ from natural and laboratory observations.
A continued accumulation of tectonic strain may eventually result in a
transition from self-similar fault networks to localized mature faults.