But exactly how much energy goes into each of these three processes is exceedingly difficult, if not impossible, to measure in the field. They found that only about 10 percent of a lab quake’s energy causes physical shaking. The overwhelming portion of a quake’s energy — on average 80 percent — goes into heating up the immediate region around a quake’s epicenter. But the other two major forms of a quake’s energy — heat and underground fracturing — are largely inaccessible with current technologies. From all these measurements, the team was able to estimate each lab quake’s energy budget.