Progress in Assessing Tsunami Risk on a Global Scale

Tsunamis produce some of the greatest losses to lives and livelihoods of any disaster. They ignore country borders, bringing chaos and destruction indiscriminately. These rare events are difficult to study, but we have learnt many valuable lessons from two of the biggest tsunamis that have occurred in the last decade: the 2004 Indian Ocean  tsunami, and the 2011 Great East Japan tsunami.

Tsunami loss is an important concern in the insurance sectors. A great deal of research has been working toward developing fragility functions for buildings and damage assessment for marine vessels. Recent research has begun to give more focus to the assessment of loss of life using historical tsunami data.

Global Tsunami Model (GTM)

Modelling tsunami damage is not a straightforward process. There are three main challenges of tsunami assessment:

  • Tsunami sources (both seismic and non-seismic) are varied and limited to only the known subduction zones, with added difficulties surrounding estimation of return periods at each rupture area, and difficulty in determining non-seismic sources such as landslide and submarine volcanic eruption.
  • Inundation mapping is difficult due to the limitations in tsunami numerical modelling and limited detailed bathymetry and topography data.
  • Vulnerability and risk research is largely focused on losses due to building damage based on only flow depth and flow velocity. Research suggests that more explanatory variables are required to develop the better risk indicators.

To meet these challenges, the tsunami assessment on global scales called the Global Tsunami Model (GTM) was initiated during a scientific meeting in June 2015. The GTM is expected to address the challenges mentioned above by focusing on five main factors through world-wide research collaborations:

  1. Tsunami source
  2. Tsunami modelling
  3. Probabilistic analysis
  4. Vulnerability assessment
  5. Tool and dissemination

World Tsunami Day (5th November)

Goryo Hamaguchi

Statue of Goryo Hamaguchi

In Japan, November 5th is the Tsunami Disaster Prevention Day. The day was chosen because of a true story called “Inamura no Hi” or, in English, “Fire of rice sheaves”.

The story is retold through the generations in honour of Goryo Hamaguchi, who lived in the region currently known as Hirogawa town, Wakayama Prefecture during the Ansei Nankai earthquake of the 5th November, 1854. He was the first in his village to notice the signs of a large tsunami heading toward the village. His quick thinking and ingenuity enabled him to lead villagers to higher ground by burning harvested rice sheaves. Seeing the burning piles of harvested rice high on the hill next to the village, the villagers rushed to extinguish the flames and save the harvest, but actually unwittingly saved themselves from the oncoming wave. Goryo Hamaguchi had cleverly evacuated the village and saved the lives of the villagers.

After this event, he also spent his own money to build an embankment along the village`s coast and helped mitigate disaster during a later tsunami which occurred in 1946. Tsunami festival is organized every year as a memorial of this great hero.

Japan designated November the 5th as Tsunami Disaster Prevention Day under a law on measures to deal with tsunami after the March 2011 disasters. Japan hopes to play a leading role in the international community in the field of disaster reduction after the March 2011 earthquake and tsunami devastated the Tohoku region.

As a result, the World Tsunami Day proposal was submitted after the third UN World Conference on Disaster Reduction in Sendai in March earlier this year, and it is hoped that this day will increase awareness of the conditions that indicate an ensuing tsunami, as well as encourage research and collaboration in to new approaches to disaster risk reduction.

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Guest bloggers Anawat Suppasri, Fumihiko Imamura, Abdul Muhari and Panon Latcharote are collaborators through the International Research Institute of Disaster Science, Tohoku University, Sendai, Japan and members of the Willis Research Network (WRN). The WRN started their collaborative research on tsunami with Tohoku University in 2010. The five-year collaboration has fostered many research projects on tsunami hazard evaluation in the Pacific and Indian Oceans and some parts of the Europe, while providing access to academic experts during the 2011 Japan Tsunami.

In 2014, Willis Re had announced their first Japan Tsunami Model along with international collaboration with Tohoku University and University College London.

imamuraProfessor of tsunami engineering, Fumihiko Imamura, joined IRIDeS (International Institute of Disaster Science), Tohoku University in 2012 as vice director, conducting the field survey of the 2011 Tohoku earthquake tsunami and coordinating the project for disaster mitigation. Became director of IRIDeS in 2014,  promoting international collaboration for DRR (Disaster Risk Reduction) since the 3rd UN world conference for DRR at Sendai.

Anawat picDr. Anawat Suppasri, PhD in Tsunami Engineering, Tohoku University 2010. As a Willis Research fellow his research is on tsunami risk assessment, tsunami numerical simulation, tsunami fragility analysis, tsunami evacuation and disaster mitigation education. Joined the IRIDeS at its establishment in 2012 as Associate Professor.

PanonDr. Panon Latcharote joined IRIDeS, Tohoku University in 2015 as a postdoctoral researcher under Willis research project, researching tsunami risk assessment, and working on tsunami hazard and risk evaluation from earthquake and landslide sources. Developing a fatality function based on life insurance data from the 2011 Great East Japan earthquake and tsunami. Panon’s background is in structural engineering within construction and design.

Abdul MuhariDr. Abdul Muhari technical officer for coastal disaster mitigation with the Ministry of Marine Affairs, Indonesia since 2005, He begun  researching  tsunami mitigation after the 2004 Indian Ocean Tsunami. From August 2008 to April 2009, he was a visiting scientist at the German Aerospace Center (DLR), near Munich, supporting the development of Indonesian Tsunami Warning System based on analysis of remotely sensed data. Pursued his PhD in Tsunami Engineering  at Tohoku University in Japan in 2009, in 2011 experienced the tsunami first-hand. He joined the Willis Research Network as a fellow between 2012-2014  conducting insurance assessment of tsunami risk in Japan.

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