Geography Reference
In-Depth Information
Fig. 20.2
Inundation height distribution of the tsunami (modifi ed after Tsunami Damage Mapping
Team, Association of Japanese Geographers
2011
)
about 5 m in an east-southeast direction. This movement spread to eastern Japan,
including all areas south of the Tohoku region.
The large vertical seafl oor uplift generated a giant tsunami that was larger than
expected by scientists. A tsunami damage mapping team of the Association of
Japanese Geographers (AJG) developed a map of the devastated area from aerial
photos, which showed the distribution of the inundation height (Fig.
20.2
). The mag-
nitudes of height fl uctuations were large in the Sanriku coastal area, with a maximum
inundated height of 30 m, attributable to the effect of a deeply indented coastline.
In the regional plains between Sendai and Ishinomaki, inundation height and magnitude
of fl uctuations were small, owing to the effect of fl at terrain. However, the inundation
distance extended several kilometers inland, resulting in a wide area of fl ooding.
Further south in Fukushima Prefecture, the inundation height was large because of
the effect of coastal terraces.
The largest damage from the tsunami was not in the Sanriku coastal area but on
the Ishinomaki and Sendai plains. A large population in this area meant that more
people were at risk. Moreover, the tsunami inundation area greatly exceeded the
assumed tsunami danger zone outlined in hazard maps created before the earthquake.
The importance of these maps was highlighted after the disaster.
