Alaska and Hawaii are thousands of miles apart. One is near the Arctic. The other sits in the middle of the Pacific Ocean. It seems like what happens in one place could not affect the other. But on April 1, 1946, an earthquake struck near the Aleutian Islands of Alaska. The quake happened deep under the ocean floor. It was powerful enough to push a massive amount of water upward. That water became a wave. A tsunami -- that traveled across the entire Pacific Ocean at speeds close to 500 miles per hour. About five hours later, that wave reached Hilo, a city on the Big Island of Hawaii. The wave was over 30 feet tall when it hit the coastline. It destroyed buildings, flooded streets, and swept away everything in its path. A total of 159 people died. The disaster revealed an important geographic fact: the Pacific Ocean connects everything around its rim. An earthquake on one side can send a dangerous wave to the other side within hours. In response, scientists created the Pacific Tsunami Warning Center in 1949. It monitors earthquakes around the Pacific and sends alerts to coastal communities when a tsunami might be on its way. The system has saved countless lives since then.