## The Hidden Energy of Earthquakes Earthquakes release energy stored in rocks over millennia. Most of this energy doesn't manifest as ground shaking but dissipates as heat and rock fracturing. ## How Much Energy Transforms into Shaking? A team at MIT conducted lab experiments to quantify the energy budget of earthquakes. They found that only 1-10% of a lab earthquake's energy causes physical shaking. The rest of the energy is divided between breaking rocks (1-30%) and heating the area around the epicenter, with temperatures that can melt the material. ## The Memory of Rocks The research also revealed that a region's tectonic history influences the distribution of seismic energy. "The deformation history—essentially what the rock remembers—really influences how destructive an earthquake could be," says Daniel Ortega-Arroyo, lead author of the study. This history affects the material properties in the rock and dictates how it will slip. ## Future Implications Understanding how an earthquake's energy is distributed between shaking, heat, and rock fracturing could help scientists assess a region's vulnerability to future seismic events. If the intensity of the shaking generated by a past earthquake is known, the impact of energy on rocks deep underground can be estimated, and the future seismic risk can be assessed.