A major earthquake releases the energy of two hundred Hiroshima bombs

Deep beneath Japan, the Pacific Plate relentlessly slides forward at about nine centimeters per year—roughly the speed a human fingernail grows. This slow-motion collision creates an invisible build-up of tension called strain, which accumulates over centuries until the crust simply cannot hold any more. When the rock finally fails, the resulting rupture can tear through the earth at three kilometers per second, a supersonic jolt that releases ten quadrillion joules of energy.