A 6.0-magnitude quake rocked southwest China's Sichuan Province on Monday. Many communities and schools in Chengdu City heard the alarm of earthquake warning 61 seconds before the initial tremor struck. An early earthquake warning system gave people vital seconds to escape the danger. The system uses a method that gives the alert tens of seconds before the arrival of the seismic waves. While the exact timing of quakes can't yet be predicted, the early warning system allows people to take immediate action that could potentially save their lives.