At 14:46 local time on March 11, 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. This earthquake generated a tsunami that struck Japan as well as various locations around the Pacific Ocean. With the participation of about 300 researchers from throughout Japan, joint research groups conducted a tsunami survey along a 2,000 km stretch of the Japanese coast. More than 5,200 locations have been surveyed to date, generating the largest tsunami survey dataset in the world. The inundation height and run-up height were surveyed by laser, GPS, and other instruments, and the tidal correction has been accurately adjusted using a tidal database and a numerical simulation for Tohoku, an area where tide gauges were destroyed by the tsunami. Based on the survey dataset, the regional and local scale analyses were conducted to understand the basic characteristics of this event. Maximum run-up heights greater than 10 m are distributed along 500 km of coast in direct distance. The affected area o...

https://www.tandfonline.com/doi/pdf/10.1142/S0578563412500015

Nationwide post event survey and analysis of the 2011 tohoku earthquake tsunami

Fragility functions, as new measures for estimating structural damage and casualties due to tsunami attack, are developed by an integrated approach using numerical modeling of tsunami inundation an...

Developing fragility functions for tsunami damage estimation using numerical model and post-tsunami data from banda aceh, indonesia

Investigations on the porous media equations and resistance coefficients for coastal structures

Tsunami fragility (fragility curve, or fragility function) is a new measure, we propose, for estimating structural damage and fatalities due to tsunami attack, by integrating satellite remote sensing, field survey, numerical modeling, and historical data analysis with geographic information system (GIS). Tsunami fragility is expressed as the structural damage probability or fatality ratio related to hydrodynamic features of tsunami inundation flow, such as inundation depth, current velocity and hydrodynamic force. It expands the capability of estimating potential tsunami damage in a quantitative manner.

Tsunami Fragility — A New Measure to Identify Tsunami Damage —

On March 11, 2011, a large earthquake that occurred offshore the north-east coast of Japan generated a large tsunami which devastated extensive areas of the Tohoku coastline. Despite Japan being considered a country well prepared for these types of disasters, large casualties were recorded, with numerous discussions amongst the Japanese coastal engineering community ensuing. As a result, two different levels of tsunamis have been proposed and now recognized in Japan, depending on the frequency of such extreme events. The idea that hard measures can protect the lives of inhabitants of coastal areas has been abandoned, and these measures are only considered to be effective in protecting properties against the more frequent but lower magnitude events. Soft measures should always be used to protect against the loss of lives, and to this respect, the authors of the paper propose the introduction of a Classification of Evacuation Areas, to show which of these should be prioritized by residents as they seek to evacuate.

Classification of Tsunami and Evacuation Areas

A new stability formula for wave-dissipating concrete blocks covering horizontally composite breakwaters is proposed after reviewing the existing stability formulae and verified using experimental data. A method for estimating the expected value of the accumulated damage to wave-dissipating concrete blocks within their lifetime using the Monte Carlo simulation follows thereafter and the practicability of this method for reliability based design of wave-dissipating concrete blocks is shown.

/pdf/new-stability-formula-for-wave-dissipating-concrete-blocks-4owbg5kxdu.pdf

New stability formula for wave-dissipating concrete blocks covering horizontally composite breakwaters

Uniformity of monochromatic oblique waves in a wave basin is investigated. A new method, using non-linear least square formulation, to determine individual wave paddle motions of multi-directional wavemaker to improve uniformity, is proposed. The possibilities and limitations of the method are discussed. Trial computations and comparisons with experiments demonstrate the validity and usefulness of the method.

/pdf/new-optimization-method-for-paddle-motion-of-multi-3axodl7wxw.pdf

New optimization method for paddle motion of multi-directional wavemaker

The Indian Ocean Tsunami occurred on 26 December 2004, causing serious damage in the Maldives, which is 2,000 km distant from the epicenter. A post-tsunami survey was carried out from 31 January to...

Survey results of the indian ocean tsunami in the maldives

In recent years, the risk of occurrence of tsunamis generated by near shore earthquakes, such as, Tokai, Tonankai, Nankai and off-Miyagi is considered to be higher than before, as well as off shore tsunamis traveling long distances, e.g., the 2010 Chilean tsunami. On March, 11th, 2011 the huge, devastating tsunami generated by The 2011 off the Pacific coast of Tohoku Earthquake attacked and damaged the east coast area of Japan. Tsunami forces onto vertical walls, such as seawalls, has already been studied in detail, e.g., Asakura et al.(2002) and Kato et al.(2006). In Japan, detached breakwaters made with wave-dissipating concrete blocks such as Tetrapods have been widely applied. However, the effects of detached breakwater on tsunami disaster mitigation have not been studied. In our study, hydraulic model tests have been systematically and carefully carried out using solitary tsunami waves to evaluate the stability of concrete blocks following the our previous study on the effect of detached breakwaters from the viewpoint of reducing run-up and wave pressure onto seawalls behind the detached breakwaters (Hanzawa et al., 2011).

/pdf/stability-of-wave-dissipating-concrete-blocks-of-detached-3o7xflom9z.pdf

Stability of wave-dissipating concrete blocks of detached breakwaters against tsunami

Detached breakwaters, made with wave-dissipating concrete blocks such as Tetrapods, have been widely applied in Japan, but the effectiveness of such kinds of detached breakwaters on tsunami disaster prevention has never been discussed in detail. A numerical wave flume called CADMAS-SURF has been developed for advanced maritime structure design. CADMAS-SURF has been applied mainly to ordinary wave conditions such as wind waves, and little attempt has been made for expanding its application to tsunami waves. In this study, the applicability of CADMAS-SURF for evaluating the effectiveness of detached breakwaters on a solitary tsunami wave reduction is investigated by comparing the calculated results with those from hydraulic experiments. First, the effectiveness of a detached breakwater on the reduction of wave height and wave pressure was confirmed both by hydraulic experiments and numerical simulations. Finally, CADMAS-SURF has been found to be a useful tool for evaluating the effects of detached breakwaters on tsunami wave height and pressure reduction, as a first step in a challenging study.

/pdf/applicability-of-cadmas-surf-to-evaluate-detached-breakwater-5cu442q5o4.pdf

Minoru Hanzawa

Papers

New stability formula for wave-dissipating concrete blocks covering horizontally composite breakwaters

New optimization method for paddle motion of multi-directional wavemaker

Survey results of the indian ocean tsunami in the maldives

Stability of wave-dissipating concrete blocks of detached breakwaters against tsunami

Applicability of CADMAS-SURF to evaluate detached breakwater effects on solitary tsunami wave reduction