Overview: One of the most important things to do to save lives from a major tsunami is to evacuate to safety as soon as possible. The key to this is fast and accurate tsunami information. Once a life-threatening tsunami is detected, people living in risk areas have to evacuate to a place where they can escape from tsunami damage. After the 2011 Great East Japan Earthquake, Japan has established a large-scale tsunami observation network on the ocean floor and is working to disseminate accurate and prompt tsunami information.