Fast to slow slip transition in analogue experiments of earthquakes

Abstract

Abstract We conducted laboratory earthquake experiments using soft polymer gels with well-defined bumps on both surfaces. We found two distinct slip modes, controlled by the position randomness of the bumps. When bumps are placed periodically, all contact junctions broke simultaneously. Consequently, fast, regular, and large slip events occurred. In contrast, when bumps are randomly positioned, slow and localized slip events prevailed, accompanied by a small stress drop. We developed a simple theoretical model that describes elastic deformation of the media, slip weakening friction for the bump pairs, and configuration irregularity in the bump position. Using this model, we successfully reproduced the fast to slow slip transition. We believe that our simple approach can contribute to understanding the role of fault heterogeneity in fast and slow earthquakes, and the physics of friction between solids.