Much like our voices create sound waves with a variety of low and high pitches, or frequencies, earthquakes produce seismic waves over a broad spectrum. The seismic waves' frequencies determine, in part, how far they travel and how damaging they are to human-made structures. However, the inaccessibility of fault zones means that very little is known about why and how earthquakes produce different frequencies. With the help of a new tabletop model, scientists have now identified how a process known as fault healing can shape seismic waves and potentially alter their frequencies.