A tsunami, sometimes referred to as a tidal wave, is a series of ocean waves created when anearthquake or other major disturbance displaces a large volume of water. Powerful tsunamis such as the 2004 Indian Ocean event can devastate coastal regions as the waves sweep far inland.
Following a quake, tsunamis can travel for thousands of miles. For example, after the 2011 Sendai earthquake in Japan, a tsunami alert was issued for almost the entire Pacific region. Places as far away as Chile were affected by the alert.