For those who study earthquakes, one major challenge has been trying to understand all the physics of a fault—both during an earthquake and at times of "rest"—in order to know more about how a particular region may behave in the future. Now, researchers at Caltech have developed the first computer model of an earthquake-producing fault segment that reproduces, in a single physical framework, the available observations of both the fault's seismic (fast) and aseismic (slow) behavior.