When you tell people to evacuate; how long do you have until the tsunami hits?
For a dangerous tsunami has been generated far away from an area, the NOAA Tsunami Warning Centers issue a tsunami watch that a dangerous tsunami may be on its way and for people to be alert for further information. A tsunami warning is issued at least 2 hours before the first wave will strike the area. The warning tells people to move to a safe place as quickly as possible.
When a tsunami is generated nearby, a tsunami warning is issued immediately. For this case, people near the ocean should also u se the natural warning signs such as a strong earthquake, the water level starts changing rapidly, or there is a new loud sound coming from the ocean.
Authority: Dr. Hal Mofjeld, interview in February 13, 2006, NOAA Center for Tsunami Research