INUNDATION FLOW VELOCITY OF TSUNAMI ON LAND AND ITS PRACTICAL USE

Hideo Matsutomi, Kensuke Okamoto, Kenji Harada

Abstract


Based on field data of inundation depth and inundation flow velocity u estimated using Bernoulli’s theorem and inundation depth, fundamental characteristics of relationship between inundation flow velocity and inundation depth are examined. Velocity coefficient Cv (= where g is gravitational acceleration, hf and hr are inundation depths at the front and the back of structure such as a rectangular building with vertical walls respectively) implicitly included in the relationship is examined through steady flow experiments. As the result, Cv0.6 is recommended as its simple and practical value. By using the relationship and Cv0.6, two simple and practical relationships are presented for two cases where inundation flow velocity exerts the largest or the smallest fluid force on structures. Fundamental characteristics of waterline (tsunami-trace) distribution around a square pillar model are also examined through steady flow experiments. Examples of tsunami-trace distribution around building in the 2009 Samoa Earthquake tsunami are presented, and compared with those by steady flow experiments. It is confirmed through the comparison and examination that the tsunami-trace distributions around buildings by the field survey are consistent with those by the steady flow experiments and contain information such as inundation flow direction, velocity and fluid force at the maximum incident inundation depth, and strength of buildings. Variation coefficient C.V. of inundation flow velocity caused by the measured point difference at the front and the back of building is also examined. In addition, based on the above results of inundation flow velocity, the existing simple and practical judgment criterion for the degree of damage to buildings is re-examined, and it is confirmed that newly proposed judgment criterion for the degree of damage to wooden buildings is consistent with the tsunami fragility curve for Japanese wooden buildings by Koshimura et al.

Keywords


tsunami; field survey; hydraulic experiments; inundation flow velocity; degree of damage to buildings

References


Iizuka, H., and H. Matsutomi. 2000. Damage due to inundation flow of tsunami, Proceedings of Coastal Engineering, JSCE, 47, 381-385. (in Japanese)http://dx.doi.org/10.2208/proce1989.47.381

Koshimura, S., M. Matsuoka, and S. Kayaba. 2009. Tsunami hazard and structural damage inferred from the numerical model, aerial photos and SAR imageries, Proceedings of 7 th International Workshop on Remote Sensing for Post Disaster Response (CD-ROM).

Matsutomi, H. 1991. An experimental study on pressure and total force due to bores, Proceedings of Coastal Engineering, JSCE, 38, 626-630. (in Japanese)http://dx.doi.org/10.2208/proce1989.38.626

Matsutomi, H. 1999. A practical formula for estimating impulsive force due to driftwoods and variation features of the impulsive force, Journal of Hydraulic, Coastal and Environmental Engineering, JSCE, 621/II-47, 111-127. (in Japanese with English abstract)

Matsutomi, H. 2009a. Method for estimating collision force of driftwood accompanying tsunami inundation flow, Journal of Disaster Research, 4, 435-440.

Matsutomi, H. 2009b. Problems in recent onshore and land tsunamis, Lecture Notes of the 45 th Summer

Seminar on Hydraulic Engineering, 2009, Course B, JSCE, B-3-1-20.

Matsutomi, H., and H. Iizuka. 1998. Tsunami current velocity on land and a simple method for estimating it, Proceedings of Coastal Engineering, JSCE, 45, 361-365. (in Japanese) http://dx.doi.org/10.2208/proce1989.45.361

Matsutomi, H., and K. Okamoto. 2010. Inundation flow velocity of tsunami on land, Island Arc, 19, Issue 3, 443-457.http://dx.doi.org/10.1111/j.1440-1738.2010.00725.x

Matsutomi, H., and N. Shuto. 1994. Tsunami inundation depth, current velocity and damage to houses, Proceedings of Coastal Engineering, JSCE, 41, 246-250. (in Japanese) http://dx.doi.org/10.2208/proce1989.41.246

Matsutomi, H., M. Fujii, and T. Yamaguchi. 2009. Experiments and development of a model on the inundated flow with floating bodies, Proceedings of the 31 st International Conference on Coastal Engineering, ASCE, 2, 1458-1470.

Matsutomi, H., K. Harada, T. Ogasawara, and S. Kataoka. 2010. A side of the 2010 Chile Earthquake tsunami, Proceedings of the 29 th Annual meeting, JSNDS. (in Japanese)

Matsutomi, H., T. Sakakiyama, S. Nugroho, and M. Matsuyama. 2006. Aspects of inundated flow due to the 2004 Indian Ocean tsunami, Coastal Engineering Journal, 48, 167-195. http://dx.doi.org/10.1142/S0578563406001350

Sakakiyama, T., H. Matsutomi, Y. Tsuji, and Y. Murakami. 2005. Comparison of tsunami inundation flow velocities based on analysis of video pictures and field survey, Tsunami Engineering Technical Report, Tohoku University, 22, 111-117. (in Japanese)

Shuto, N., F. Imamura, S. Koshimura, K. Satake, and H. Matsutomi. 2007. Encyclopedia of tsunamis, Asakura Publishing Co., Ltd., Tokyo, 350 pp. (in Japanese) PMCid:1868898

USGS. 2009. Magnitude 8.1 - SAMOA ISLANDS REGION. http://earthquake.usgs.gov/eqcenter/eqinthenews/2009/us2009mdbi/


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