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No. 10, between Shiogama city and Watari town), managed by
Miyagi Prefecture. The other is the Sendai-Tobu Road (the 24.8
km long highway, a part of National Road No. 6), managed by
the Japanese central Government. It is interesting to know that
these two roads are located on the borders of assumed tsunami
events. The Shiogama-Watari Line (thick orange coloured solid
line) forms a border between the Level 1 and Level 2 areas, on a
6 m bank, which can be a tsunami barrier for Level 2 areas. The
Sendai-Tobu highway (thick blue coloured solid line) forms a part
of the upper border of the Level 2 area. Combined with these two
roads, Sendai city has newly revised its tsunami hazardmap. These
road banks can also be used for evacuation during tsunami events.
The conceptual diagram in Figure 1 can be recognized in
Figure 4 for the 2011 tsunami hazard, which was too big for
people to escape from it:
(a) almost all exposures (people and properties) in the
vulnerable place were completely damaged
(b) exposures were assumed to be safe from the tsunami
because they were in safer places
(c) vulnerable places were damaged by liquefaction or land
subsidence, which affected agricultural lands (mainly
rice paddy fields) through salt water from the sea
(d) safer places were also damaged because the tsunami
run-up height at some locations in the middle and
upstream of rivers was 40 m high.
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Figure 2: The tsunami hazard map for Sendai
before 11 March 2011
Source: Geographical Survey Institute of Japan
Figure 3: The tsunami hazard map for Sendai after 11 March 2011
Source: Sendai City home page
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