When you rub your hands together to warm them, the friction creates heat. The same thing happens during earthquakes, only on a much larger scale: When a fault slips, the temperature can spike by hundreds of degrees, high enough to alter organic compounds in the rocks and leave a signature. A team of scientists at Columbia University’s Lamont-Doherty Earth Observatory has been developing methods to use those organic signatures to reconstruct past earthquakes and explore where those earthquakes started and stopped and how they moved through the fault zone. The information could eventually help scientists better understand what controls earthquakes.