136
In the present chapter we discuss how these different time scales impact the
framing of disaster preparedness and risk reduction using two different case studies.
The first relates to tsunami disaster risk management in Japan, and the second to sea
level rise using the point of view of low-lying islands and coral reefs as an indication of how time scales affect the perception of the problems involved.
7.2 Natural Hazard Return Periods: Tsunami Classification
in Japan
On March 11, 2011 a large earthquake of magnitude 9.0 on the Richter scale
occurred off the northeast coast of Japan, generating a devastating tsunami that
inundated over 400 km
2
of land, and caused large numbers of casualties (Mori et al.
2012, Mikami et al. 2012; Ogasawara et al. 2012). Along the Sendai plain in northern Tohoku the maximum inundation height was 19.5 m, and the tsunami propagated as a bore around 4–5 km inland, with maximum run-up-heights of 40.4 m
being measured (Mori et al. 2012). Widespread devastation ensued, as the waves
engulfed entire settlements, with everything but the sturdiest of buildings being
completely washed away (see Fig. 7.1). This event is now known as the 2011 Tohoku
Earthquake Tsunami.
This event has transformed the way that the Japanese engineering and coastal
zone management community think about tsunamis. Their approach to time scales
is discussed in detail in the rest of this section.
7.2.1 History of Tsunamis in Northern Japan (Tohoku region)
Historically, the 2011 Tohoku Earthquake Tsunami was one of the worst tsunamis
that has affected Japan since records began. The Sanriku coastline, which extends
northwards from the city of Sendai, has been frequently affected by tsunamis. The
recorded history in the region goes back over 1000 years, and five major destructive
tsunamis are all well documented (Watanabe 1985):
1. Jogan (869),
2. Keicho (1611),
3. Meiji-Sanriku (1896),
4. Showa-Sanriku (1933), and
5. Chile (1960).
In fact, the 2011 Tohoku Earthquake Tsunami has been described as a one-in-a1000-year event, resembling the Jogan Tsunami in A.D. 869 (Sawai et al. 2006).
The description of this Jogan Tsunami actually appears in a historical document
known as the Sandai-Jitsuroku, which documents how the wave flooded a wide
M. Esteban et al.
In the present chapter we discuss how these different time scales impact the
framing of disaster preparedness and risk reduction using two different case studies.
The first relates to tsunami disaster risk management in Japan, and the second to sea
level rise using the point of view of low-lying islands and coral reefs as an indication of how time scales affect the perception of the problems involved.
7.2 Natural Hazard Return Periods: Tsunami Classification
in Japan
On March 11, 2011 a large earthquake of magnitude 9.0 on the Richter scale
occurred off the northeast coast of Japan, generating a devastating tsunami that
inundated over 400 km
2
of land, and caused large numbers of casualties (Mori et al.
2012, Mikami et al. 2012; Ogasawara et al. 2012). Along the Sendai plain in northern Tohoku the maximum inundation height was 19.5 m, and the tsunami propagated as a bore around 4–5 km inland, with maximum run-up-heights of 40.4 m
being measured (Mori et al. 2012). Widespread devastation ensued, as the waves
engulfed entire settlements, with everything but the sturdiest of buildings being
completely washed away (see Fig. 7.1). This event is now known as the 2011 Tohoku
Earthquake Tsunami.
This event has transformed the way that the Japanese engineering and coastal
zone management community think about tsunamis. Their approach to time scales
is discussed in detail in the rest of this section.
7.2.1 History of Tsunamis in Northern Japan (Tohoku region)
Historically, the 2011 Tohoku Earthquake Tsunami was one of the worst tsunamis
that has affected Japan since records began. The Sanriku coastline, which extends
northwards from the city of Sendai, has been frequently affected by tsunamis. The
recorded history in the region goes back over 1000 years, and five major destructive
tsunamis are all well documented (Watanabe 1985):
1. Jogan (869),
2. Keicho (1611),
3. Meiji-Sanriku (1896),
4. Showa-Sanriku (1933), and
5. Chile (1960).
In fact, the 2011 Tohoku Earthquake Tsunami has been described as a one-in-a1000-year event, resembling the Jogan Tsunami in A.D. 869 (Sawai et al. 2006).
The description of this Jogan Tsunami actually appears in a historical document
known as the Sandai-Jitsuroku, which documents how the wave flooded a wide
M. Esteban et al.