Dr. Lane and Boomer chase just behind the expanding crack in the Earth's crust, developing a plan to stop the next quake. They decide to use a satellite orbiting above the continent which can trigger earthquakes. They fire it off when they reach the Grand Canyon, thinking that when the new fault hits the canyon it will be forced to turn south into the Gulf of Mexico. When the fault crosses with the canyon, they fire the satellite at the canyon but plan goes wrong. Instead of heading south, the fault travels north, towards the Yellowstone Caldera.