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Research Institute 2011 ). The latter was exacerbated by the
arrival of the tsunami at high tide at many places. The
tsunami broke 125 km 2 of ice off the Sulzberger Ice Shelf in
Antarctica, 13,000 km away (Brunt et al. 2011 ).
International Tsunami Survey teams entered the affected
areas soon afterwards to measure the heights of run-up, flow
water depths, flow directions, topographic influence on
flow, and the extent and thickness of sediment deposits
(Earthquake Engineering Research Institute 2011 ; Goto
et al. 2012 ). The purpose of these field investigations was to
examine how tsunami characteristics varied with tsunami
speed and flow depth, and distance from the coast; and how
the tsunami interacted with topography and the built envi-
ronment. Crucially scientists wanted to know if there was
evidence of previous large events. On the rocky Sanriku
coast, the T ¯ hoku Tsunami moved a considerable number
of boulders weighing between 11 and 167 t up to 600 m
inland (Nandasena et al. 2013 ). In all cases, boulders were
transported by rolling. Maximum flow velocities exceeded
4.2-5.0 m s -1 and may have been as high as 21.7 m s -1 .
Worrisome, an older boulder weighing 285 t was found in
Settai that was probably transported by the Keicho Sanriku
Tsunami in 1611. It had not been moved by the modern
event and would have required even higher velocities to be
transported. The T ¯hoku Tsunami also deposited sand
2.8 km inland on the Sendai plain (Richmond et al. 2012 ;
Wilson 2011 ); however, the tsunami had travelled 2.6 km
further inland than this (Goto et al. 2012 ). Paleo-tsunami
deposits had been found for the July 13, 869 Jogan Tsu-
nami, generated by a smaller, modeled, tsunamigenic
earthquake with a M w moment magnitude of 8.3-8.4 (Abe
et al. 1990 ; Minoura et al. 2001 ; Satake et al. 2008 ). This
latter fact lead to the false assumption that the area could
not be affected by great earthquakes and tsunami. Else-
where, an older palaeotsunami deposit had been found
dating at 3000 years BP (Minoura et al. 2001 ; Sawai et al.
2008). From the paleo-studies it was known before the
T ¯hoku Tsunami that the Sendai plain and, by association,
the Sanriku coast was affected by great tsunami every
800-1100 years (Minoura et al. 2001 ). The surveys after the
T ¯hoku Tsunami confirmed the paleo-evidence (Wilson
2011 ; Okamura 2013 ). This research has led to two worri-
some conclusions. First, many other devastating events are
known that appear to have left no prominent sedimento-
logical signature in the form of buried sand layers. The
1896 Meiji and 1933 Showa Tsunami are examples of this.
Second, and crucially, the T ¯hoku Tsunami flowed much
further inland without leaving any widespread, sedimento-
logical signature (Okamura 2013 ). This has implications for
studies of pre-historic events based upon the mapping of
buried sand layers described in Chap. 2 . These paleo-events
most likely affected a larger area than that inferred from the
distributions of anomalous sand deposits.
In Japan, the death toll and economic loss were extraor-
dinary. Over 23,295 people are estimated to have lost their
lives. This figure is difficult to finalise because of the number
of people who went missing—6,145 persons—and the fact
that some deaths were caused by the actual earthquake. The
economic loss has been estimated at $300 billion, making it
the most costly disaster of all time (Earthquake Engineering
Research Institute 2011 ). Damage consisted of 126,602
buildings totally collapsed, with a further 272,426 buildings
'half collapsed', and another 743,089 buildings partially
damaged; 116 bridges destroyed; and 29 railways damaged
(National Police Agency of Japan 2013 ). Many towns were
obliterated (Fig. 6.18 ). The affected coastline contained
15 major ports and 319 minor fishing ones. Four of the
former were destroyed and all suffered damage (Reuters
2011 ). The most significant facility damaged was the
Fukushima Daiichi Nuclear Power Plant complex
(Fig. 6.16 c). The reactors automatically switched off fol-
lowing the earthquake and emergency generators maintained
the cooling system (Povinec et al. 2013 ). However 55 min
after the earthquake a 15 m high tsunami swamped 12 of the
13 generators located in the basement of the turbine build-
ing. The wave height was twice that designed for the com-
plex. Without cooling, meltdown began in three of the
reactors and hydrogen gas was produced by the exothermic
reaction of the fuel's zirconium cladding with steam and
water at high temperatures. The containment vessels sub-
sequently exploded over the next two days spreading ra-
dionuclides across the site and releasing them into the
atmosphere. This created one of the most significant nuclear
accidents in history. Over 4,500 fuel rods were left with
insufficient cooling. Readings of 400 mSv hr -1 were
recorded at the reactors, enough to give a human a lethal
dose within minutes (The Asahi Shimbun 2011 ). A total of
146,520 residents within a 20 km radius of the complex
were evacuated. Many may never be able to go home again.
However, radiation spread beyond this exclusion zone,
mainly to the northwest where readings of cumulative
ambient dose, integrated until the end of March 2011,
reached over 10 mSv more than 40 km from the reactors.
Agricultural produce outside the containment zone was
polluted by radiation. Lettuce 60 km from the plant in
Fukushima Prefecture contained 164 times the permissible
level of cesium. A month after the tsunami, the severity
rating of the nuclear disaster was raised to level 7, the same
rating as the Chernobyl disaster of 1986.
The effects of this disaster continue to date. Firstly, the
broken Fukushima Nuclear Plant has not been contained.
Approximately 380,000 tonnes of irradiated water used to
cool the exposed fuel rods has been stored in 1,000 tanks on
site (Varma 2013 ). About 300 of these tanks were never
intended to hold radioactive liquid waste and have faulty
seals. Over 300 tonnes of contaminated water has leaked
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