The document discusses tsunamis, defining them as huge waves caused by the movement of tectonic plates under the ocean. It provides vocabulary related to tsunamis, natural disasters, and oceanography. The document notes that while tsunamis can't be prevented, communities can prepare by evacuating to high ground and having emergency supplies. Tsunamis are caused by underwater earthquakes that push water upwards, creating massive waves that cause property damage and pollution. Japan experiences many tsunamis due to its location next to an active tectonic plate boundary.