Japan earthquake: Wave forecast map
- A tsunami is a series of waves - the first may not be the largest
- Wave heights cannot be predicted and can vary along a coast due to local effects
- The time from one tsunami wave to the next can be five minutes to an hour
Tsunami warnings were issued for coastal areas across the Pacific basin - from Hawaii to Chile - as a result of the waves triggered by the Japan earthquake.
This map shows the Pacific Tsunami Warning Center's "tsunami forecast model" of wave heights above normal sea level across the region and how long after the 0546 GMT earthquake they were expected.
The tsunami was triggered by the most powerful earthquake to hit Japan since records began. The tremor, measured at 8.9 by the US Geological Survey, hit at 1446 local time (0546 GMT) at a depth of about 24km.
The impact has been devastating, with cars, ships and buildings swept away by a wall of water.