Non-self-similar earthquakes generated by size- and shape-controlled asperities on a 4-meter laboratory fault

visio.numerique.gouv.fr/hym-wjxa-fxv

Abstract:

Earthquakes generally follow self-similar scaling over a wide range of magnitudes, from laboratory to natural scales, providing insight into underlying source mechanisms. Some earthquake clusters, however, deviate from this scaling, exhibiting nearly constant source durations regardless of seismic moment. Although several models have been proposed, the source mechanism is not yet well constrained due to observational uncertainties, including instrumental response and unmodeled attenuation.
To address this limitation, we conducted experiments on a 4-meter laboratory fault, introducing thin circular gouge patches (ϕ = 8 mm) as size- and shape-controlled asperities. The resulting events exhibit non-self-similar scaling even after correcting for instrumental response and attenuation. Based on the observed source parameters and patch configurations, we develop a dynamic rupture model that quantitatively explains this behavior. This study proposes a source model complementary to previous frameworks and extends the conditions under which non-self-similar earthquakes occur.