Comprehensive Research on Tsunami Hazard Mitigation

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Japan Academy Prize to:

Nobuo 

S

huto

Emeritus Professor, Tohoku University

for “Comprehensive Research on Tsunami 

Hazard Mitigation”

Outline of the work:

Tsunamis are induced by earthquakes, volcanic eruptions, or coastal submarine or subaerial landslides. 

Among these, underwater earthquakes are the primary cause of major tsunami events. Because several major 

tsunamis have occurred recently, the topic of tsunami hazard is of great concern to us.

Since the 1960 Chile Earthquake and Tsunami, Dr. Nobuo Shuto has devoted himself to tsunami research, 

including creation of the field “Tsunami Engineering.” His research is well recognized both nationally and 

internationally, and he has contributed to tsunami hazard mitigation and reduction for many communities.

Dr. Shuto’s research can be classified into two categories. First, his development methodologies used to 

predict tsunami characteristics and behaviors in the near-shore environment where human activity is directly 

affected. Second, his quantification of tsunami damage.

In the rebuilding from the 2011 Tohoku Earthquake and Tsunami, a combination of these two research 

categories is being utilized to guide the optimal siting of residential zones as well as the structural 

requirements for residential buildings. 

1. Establishment of Tsunami Numerical Method

1.1 Identification of Tsunami Characteristics

Tsunamis are long waves, with wavelengths much longer than the water depth. Even if wave amplitude 

were 10m high in deep water, the wave height can be considered small in comparison to its wavelength and 

the water depth. Therefore, linearized water-wave theory is appropriate for the tsunami modeling. However, 

wave height increases as tsunamis advance into shallow water, so now nonlinear water-wave theory should be 

applied in the shallow water. Furthermore, the nonlinear dispersive wave theory should be used to model a 

tsunami when its leading wave takes the form of undular bore (i.e., a series of shorter waves with the period 

of approximately 10s riding on a long heave of a tsunami).

Observing the 1983 Nihon-Kai Chubu Earthquake and Tsunami, Dr. Shuto recognized that the appropriate 

theory used to model tsunamis depends on a tsunami’s evolutionary behavior. The 1983 tsunami event 

exhibited the formation of undular bores when advancing into the rivers, and even in the open coastal sea.

1.2 Controlling Errors Associated with the Numerical Computation

Most numerical algorithms involve the discretization in space and time. Accuracy depends on the size of 

the discretized grid; the finer the grid size, the smoother the solution will be. Nevertheless, the discretized 

finite differences produce the accumulation of truncation error. As a result, the numerical computation could 

result in unreasonably flat wave profiles when an inadequately coarse grid size is used.

To examine the truncation error, the numerical results are often compared with the analytical counterpart. 

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However, because tsunami runup motion is highly nonlinear, the analytical approach is complex. By carefully 

examining the basic water-wave formulation, Dr. Shuto derived a simplified analytical solution. Based on his 

solution,  he  developed  the  criteria  to  achieve  improvement  in  computational  accuracy.  Specifically,  he 

developed the criteria for the spatial grid size to circumvent unwanted numerical dispersion so that a tsunami 

would maintain its waveform in a constant water depth: namely, there must be at least 20, possibly 30, spatial 

grid points to cover one tsunami wavelength. In addition, Dr. Shuto established the criteria to control 

numerical instability for simulations of a tsunami’s dry-land runup.

All of these criteria for numerical computations developed by Dr. Shuto are now widely used, not only in 

Japan, but also around the world.

1.3 International Contribution

During 1990’s, Japan and Morocco made a joint proposal that was unanimously approved by the Member 

States of the United Nations and proclaimed the International Decade for Natural Disaster Reduction 

(IDNDR). As one of the cooperative projects, the International Union of Geodesy and Geophysics (IUGG) 

and the UN UNESCO Intergovernmental Oceanographic Commission (IOC) formed a partnership to develop 

a methodology to produce tsunami inundation maps; this project is called TIME (Tsunami Inundation 

Modeling Exchange). Dr. Shuto led this project, making the numerical model of Tohoku University accessible 

without fees. Soon, his numerical model became the standard for UNESCO/IOC, and was transferred to 24 

countries and 52 organizations, including the United States, Korea, Turkey, and Mexico. This model-share 

program has three basic conditions. First, participants must be a nonprofit organization. Second, the TIME 

project must be acknowledged in publications. And third, any problems arising in the modeling must be 

reported to Tohoku University. The last condition is intended to assure credibility in the computational results 

and also to share the technical expertise of Tohoku University.

In recognition for his research and other activities that span more than 30 years, Dr. Shuto received the 

International Coastal Engineering Award from the American Society of Civil Engineers in September 1996, 

and the 14th Japan Water Prize/International Contribution in July 2012.

2. Quantitative Measure for Tsunami Strength

To  express  the  significance  of  tsunamis,  we  often  use  the  scale  commonly  referred  to  as  “tsunami 

magnitude”. But this parameter represents the total energy of a tsunami event as a whole. Tsunami effects, 

however, depend on local conditions. The idea of expressing a tsunami’s local effects was not new, but 

descriptions had been mostly qualitative; for example, “the tsunami strength was at such a level, because the 

boats offshore were washed away”.

Dr. Shuto systematically studied historical data and information, correlating tsunami damage with 

inundation depths. Such damage included buildings, ships, and aquaculture rafts, as well as the effects and 

limitations of coastal forests, and the extraordinary sound generation due to tsunamis near the shore. 

For  example,  Level-1  Tsunami  Strength,  which  is  equivalent  to  a  tsunami  height  of  2m,  induces  total 

destruction of wood-frame buildings. This tsunami strength level is the basis for issuing building permits in 

residential development lands in the areas affected by the 2011 Tohoku Earthquake and Tsunami: building 

permits are currently issued to cases where the predicted tsunami inundation depth is less than 2m.

As described above, Dr. Shuto has made tremendous contributions to quantitative modeling of tsunamis in 

coastal waters and lands. His leadership in working to categorize local tsunami strengths has set the direction 

for tsunami hazard mitigation and reduction practice. Dr. Shuto has continually played a leading role in 

planning national and international communities for tsunamis, and his contributions to tsunami science and 

hazard mitigation are truly invaluable.

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List of Publications

I-1. Basic Theory

  1.  Shuto, N.: Run-up of long waves on a sloping beach, Coastal Engineering in Japan, Vol.10, pp.23-38, 

1967.

  2.  Shuto, N.: Three dimensional behavior of long waves on a sloping beach, Coastal Engineering in Japan, 

Vol.11, pp.53-58, 1968.

  3.  Shuto, N.: Standing long waves in front of a sloping dike, Coastal Engineering in Japan, Vol.15, pp.13-23, 

1972.

  4.  Shuto, N.: Shoaling and deformation of nonlinear long waves, Coastal Engineering in Japan, Vol.16, pp.1-

12, 1973.

  5.  Shuto, N.: Nonlinear long waves in a channel of variable section, Coastal Engineering in Japan, Vol.17, 

pp.1-17, 1974.

  6.  Shuto, N.: Dispersion and nonlinearity in tsunami computation, Coastal Engineering in Japan, Vol.20, 

pp.17-25, 1977.

  7.  Tanaka, H. and N. Shuto: Friction laws and flow regimes under wave and current motion, Journal of Hy-

draulic Research, Vol.22, No.4, pp.245-261, 1984.

  8.  Fujima, K. and N. Shuto: Formulation of friction laws for long waves on a smooth dry bed, Coastal Engi-

neering in Japan, Vol.33, No.1, pp.25-47, 1990.

  9.  Takahashi, To., F. Imamura and N. Shuto: Tsunami-induced current and change of the sea bottom configu-

ration, Proc. Coastal Engineering, JSCE, Vol.38, pp.161-165, 1991 (in Japanese).

10.  Koshimura, S., F. Imamura and N. Shuto: Propagation of obliquely incident tsunamis on a slope, Part II: 

Characteristics of on-ridge tsunamis, Coastal Engineering Journal, Vol.41, No.2, pp.165-182, 1999.

I-2. Numerical method and application

11.  Shuto, N. and T. Goto: Numerical simulation of tsunami run-up, Coastal Engineering in Japan, Vol.21, 

pp.13-20, 1978.

12.  Shuto, N.: Artificial short-period oscillation in computation of tsunami run-up, Proc. Coastal Engineering, 

JSCE, Vol.26, pp.66-69, 1979 (in Japanese).

13.  Goto, C., J. Sasaki and N. Shuto: Transport of lumbers due to tsunamis, Proc. Coastal Engineering, JSCE, 

Vol.29, pp.491-495, 1982 (in Japanese).

14.  Goto, C. and N. Shuto: Numerical simulation of tsunami propagations and run-up, Tsunamis: Their Sci-

ence and Engineering, Advances in Earth and Planetary Sciences, Terra Scientific Publishing Co. and D. 

Reidel Publishing Co., pp.439-451, 1983.

15.  Goto, C. and N. Shuto: Effects of large obstacles on tsunami inundations, Tsunamis: Their Science and 

Engineering, Advances  in  Earth  and  Planetary  Sciences, Terra  Scientific  Publishing  Co.  and  D.  Reidel 

Publishing Co., pp.511-525, 1983.

16.  Fujima,  K.,  C.  Goto  and  N.  Shuto: Accuracy  of  nonlinear  dispersive  long  wave  equations,  Journal  of 

JSCE, No.369/II-5, pp.223-232, 1986 (in Japanese).

17.  Shuto, N., T. Suzuki, K. Hasegawa and K. Inagaki: A study of numerical techniques on the tsunami propa-

gation and run-up, Science of Tsunami Hazards, Vol.4, No.2, pp.111-124, 1986.

18.  Sayama, J., N. Shuto and C. Goto: Errors induced by refraction in tsunami numerical simulation, Proceed-

ings of the 6

th

 Congress APRD, IAHR, Vol.IV, pp.257-264, 1986.

19.  Imamura, F., C. Goto and N. Shuto: Numerical simulation of the transoceanic propagation of the 1964 

Alaska tsunami, Proc. Coastal Engineering, JSCE, Vol.33, pp.209-213, 1986 (in Japanese).

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20.  Imamura, F., O. Nagano, C. Goto and N. Shuto: Numerical simulation of the transoceanic propagation of 

the 1960 Chilean tsunami, Proc. Coastal Engineering, JSCE, Vol.34, pp.172-176, 1987 (in Japanese).

21.  Sayama, J., F. Imamura, C. Goto and N. Shuto: Highly accurate numerical simulation of tsunamis in the 

open ocean, Proc. Coastal Engineering, JSCE, Vol.34, pp.177-181, 1987 (in Japanese).

22.  Goto, C., F. Imamura and N. Shuto: Study on numerical simulation of the transoceanic propagation of tsu-

namis, Part 1: Governing equation and mesh length, Journal of Seismological Society of Japan, Vol.41, 

No.4, pp.515-526, 1988 (in Japanese).

23.  Imamura, F. and N. Shuto: Effect of the estimation errors in fault parameters on tsunami heights, Proc. 

Coastal Engineering, JSCE, Vol.36, pp.178-182, 1989 (in Japanese).

24.  Imamura, F. and N. Shuto: Tsunami propagation simulation by use of numerical dispersion, Numerical 

Methods in Fluid Dynamics I, edited by M. Yasuhara, H. Daiguji and K. Oshima, Japan Society of Com-

putational Fluid Dynamics, pp.390-395, 1989.

25.  Shuto, N., C. Goto and F. Imamura: Numerical simulation as a means of warning for near-field tsunamis, 

Coastal Engineering in Japan, Vol.33, No.2, pp.173-193, 1990.

26.  Imamura, F., N. Shuto and C. Goto: Study on numerical simulation of the transoceanic propagation of tsu-

namis, Part 2: Characteristics of tsunami propagating over the Pacific Ocean, Journal of Seismological 

Society of Japan, Vol.431, No.3, pp.389-402, 1990 (in Japanese).

27.  Imamura, F., Y. Izutani and N. Shuto: Accuracy of tsunami numerical forecasting with the rapid estima-

tion method of fault parameters, - A case of two fault planes with different stress drop of the 1944 Tonan-

kai Earthquake-, Journal of Seismological Society of Japan, Vol.44, No.3, pp.211-219, 1991 (in Japanese).

28.  Nagano, O., F. Imamura and N. Shuto: A numerical model for far-field tsunamis and its application to pre-

dict damage done to aquaculture, E.N.Bernard (ed.) Tsunami Hazard, Kluwer Academic Publishers, 

pp.235-255, 1991.

29.  Kawamata, S., F. Imamura and N. Shuto: Numerical simulation of the 1883 Krakatau Tsunami, Proceed-

ings of XXV Congress of International Association for Hydraulic Research, Vol.IV, pp.24-31, 1993.

30.  Takahashi, T., F. Imamura and N. Shuto: Numerical simulation of topography change due to tsunamis, 

Proceedings of the IUGG/IOC International Tsunami Symposium, pp.243-255, 1993.

31.  Noji, M., F. Imamura and N. Shuto: Numerical simulation of movement of large rocks transported by tsu-

namis, Proceedings of the IUGG/IOC International Tsunami Symposium, pp.189-197, 1993.

32.  Imamura, F., N. Shuto, B.H. Choi and H.J. Lee: Visualization of Nicaraguan Tsunami in September 1992, 

Proceedings of the IUGG/IOC International Tsunami Symposium, pp.647-656, 1993.

33.  Matsuyama, M., F. Imamura and N. Shuto: Analysis of the 1992 Nicaraguan Earthquake Tsunami, Proc. 

Coastal Engineering, JSCE, Vol.40, pp.647-656, 1993 (in Japanese).

34.  Shuto, N., K. Chida and F. Imamura: Generation mechanism of the first wave of the 1983 Nihonkai-Chu-

bu Earthquake Tsunami, Tsuchiya, Y. and N. Shuto (ed.) Tsunami: Progress in Prediction, Disaster Pre-

vention and Warning, Kluwer Academic Publishers, pp.37-53, 1995.

35.  Takahashi, To., Ta. Takahashi, N. Shuto, F. Imamura and M. Ortiz: Source models for the 1993 Hokkaido 

Nansei-Oki Earthquake Tsunami, Pure and Applied Geophysics, Vol.144, Nos. 3/4, pp.747-767, 1995.

36.  Koshimura, S., F. Imamura, To. Takahasi and N. Shuto: Tsunami characteristics as a boundary wave and 

its numerical simulation, Proc. Coastal Engineering, JSCE, Vol.43, pp.276-280, 1996 (in Japanese).

37.  Takahashi, T., N. Shuto, F. Imamura and D. Asai: Modeling sediment transport due to tsunamis with ex-

change rate between bed load layer and suspended load layer, Coastal Engineering 2000, pp.1508-1519, 

2001.

38.  Sugawara, D., K. Minoura, F. Imamura, T. Takahashi and N. Shuto: A huge dome formed by the 1854 

Earthquake in Suruga Bay, Central Japan, ISET Journal of Earthquake Technology, Paper No.462, No.4, 

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pp.147-158, December, 2005.

39.  Fujii, H., S. Hotta and N. Shuto: Numerical simulation of damage to a soil embankment from tsunami 

overflow, Journal of Disaster Research, Vol.4, No.6, pp.469-478, 2009. 

II. Disasters and Countermeasures

40.  Horikawa, K. and N. Shuto: Tsunami disasters and protection measures in Japan, Tsunamis: Their Science 

and Engineering, Advances in Earth and Planetary Sciences, Terra Scientific Publishing Co. and D. Reidel 

Publishing Co., pp.9-22,1983.

41.  Shuto, N.: The Nihonkai-Chubu Earthquake Tsunami on the North Akita Coast, Coastal Engineering in 

Japan, Vol.28, pp.255-264, 1985.

42.  Shuto, N. : The effectiveness and limit of tsunami control forests, Coastal Engineering in Japan, Vol.30, 

pp.143-153, 1987.

43.  Shuto, N.: Spread of oil and fire due to tsunamis, Proc. of International Tsunami Symposium, pp.188-204, 

1987.

44.  Shuto, N.: Change of tsunami disasters and problems to be solved in countermeasures, Proc. Coastal En-

gineering, JSCE, Vol.35, pp.237-241, 1988 (in Japanese).

45.  Shuto, N.: Tsunami intensity and disasters, Tsunamis in the World, Kluwer Academic Publishers, pp.197-

216, 1993.

46.  Matsutomi, H. and N. Shuto: Damage to houses due to tsunami in relation with inundation depth and cur-

rent velocity, Proc. Coastal Engineering, JSCE, Vol.41, pp.246-250, 1994 (in Japanese).

47.  Shuto, N. and H. Matsutomi: Field survey of the 1993 Hokkaido Nansei-Oki Earthquake Tsunami, Pure 

and Applied Geophysics, Vol.144, Nos.3/4, pp.649-663, 1995.

48.  Shuto, N.: Tsunami, disasters and defense works in case of the 1993 Hokkaido Nansei-Oki Earthquake 

Tsunami, Tsuchiya, Y. and N. Shuto (ed.) Tsunamis: Progress in Prediction, Disaster Prevention and Warn-

ing, Kluwer Academic Publishers, pp.263-276, 1995.

49.  Shuto, N.: A natural warning of tsunami arrival, Advances in Natural and Technological Hazard Research, 

Vol.9, pp.157-173, 1997.

50.  Minoura, K., F. Imamura, T. Takahashi and N. Shuto: Sequence of sedimentation processes caused by the 

1992 Flores Tsunami: Evidence from Babi Island, Geology, Vol.25, No.6, pp.523-526, 1997.

51.  Shuto, N.: Traffic hindrance after tsunamis, Advances in Natural and Technological Hazards Research, 

Vol.18, pp.65-74, 2001.

52.  Shuto, N.: Examples and hydrodynamic explanation of topographic changes caused by tsunamis, The 

Quaternary Research, Vol.46, No.6, pp.509-516, 2007 (in Japanese).

53.  Shuto, N.: Damage to coastal structures by tsunami-induced currents in the past, Journal of Disaster Re-

search, Vol.4, No.6, pp.462-468, 2009.

54.  Suppasri, A., A. Muhari, P. Ranasinghe, E. Mas, N. Shuto, F. Imamura and S. Koshimura: Damage and re-

construction after the 2004 Indian Ocean tsunami and the 2011 Great East Japan tsunami, Journal of Nat-

ural Disaster Science, Vol.34, No.1, pp.19-39, 2012.

55.  Suppasri, A., N. Shuto, F. Imamura, S. Koshimura, E. Mas and A.C. Yalciner: Lessons learned from the 

2011 Great East Japan tsunami: Performance of tsunami countermeasures, coastal buildings and tsunami 

evacuation in Japan, Pure and Applied Geophysics, Vol.170, pp.993-1018, 2013.

III. Public Education and Disaster Culture

56.  Karatani, Y., S. Koshimura and N. Shuto: A basic study on construction of the knowledge framework on 

tsunami disaster mitigation aimed at sustainable disaster prevention education, Proc. Coastal Engineering, 

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JSCE, Vol.50, pp.1331-1335, 2003 (in Japanese).

57.  Shuto, N.: Durable memory in relation to succession of disaster culture, Report of Tsunami Engineering, 

No.25, pp.175-184, 2003 (in Japanese). 

58.  Shuto, N.: Human reaction to the 1993 Showa Sanriku Great Tsunami, Report of Tsunami Engineering, 

No.27, pp.19-41, 2010 (in Japanese).