TY - JOUR A1 - Davidsen, Joern A1 - Kwiatek, Grzegorz A1 - Charalampidou, Elli-Maria A1 - Goebel, Thomas A1 - Stanchits, Sergei A1 - Rueck, Marc A1 - Dresen, Georg T1 - Triggering Processes in Rock Fracture JF - Physical review letters N2 - We study triggering processes in triaxial compression experiments under a constant displacement rate on sandstone and granite samples using spatially located acoustic emission events and their focal mechanisms. We present strong evidence that event-event triggering plays an important role in the presence of large-scale or macrocopic imperfections, while such triggering is basically absent if no significant imperfections are present. In the former case, we recover all established empirical relations of aftershock seismicity including the Gutenberg-Richter relation, a modified version of the Omori-Utsu relation and the productivity relation-despite the fact that the activity is dominated by compaction-type events and triggering cascades have a swarmlike topology. For the Gutenberg-Richter relations, we find that the b value is smaller for triggered events compared to background events. Moreover, we show that triggered acoustic emission events have a focal mechanism much more similar to their associated trigger than expected by chance. Y1 - 2017 U6 - https://doi.org/10.1103/PhysRevLett.119.068501 SN - 0031-9007 SN - 1079-7114 VL - 119 PB - American Physical Society CY - College Park ER -