JUST after 2:46 pm on March 11, before the Sendai earthquake and tsunami, Professor Kensuke Watanabe’s cell phone received an earthquake warning. He immediately told his students to hide under their desks. The university building then began to shake. But thanks to that warning, Watanabe and his students were not hurt. “It was terrifying, but the mobile warning really helped,” Watanabe told Time.com.