Figure 1: (Top) A global map of earthquake epicenters, showing clustering in space, predominantly, but not exclusively, at plate boundaries. (Bottom) A thin section of a rock sample, imaged under a microscope after a laboratory compaction experiment. The indicated tensile microfractures have the potential to generate acoustic emissions as they break. The work of Barò et al. shows that laboratory-scale fracture experiments follow the fundamental statistical laws that describe the occurrence of earthquakes.