Researchers surveyed 2000 kilometers of Japanese coastline, including over 5300 locations.
The resulting map, above, shows how severe the tsunami was in different regions of Japan.
Red bars show the height above sea level of the resulting flood, which in some places was as much as 19.5 metres.
The blue shading illustrates how far inland the tsunami travelled.
The researchers say it is still not possible to accurately predict how a given tsunami will behave once it hits the land.