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GREAT EAST JAPAN DISASTER SURVEY: TSUNAMI

Weathernews wishes to offer our deepest sympathy to all the victims of the Great Japan Earthquake. We also wish to extend our gratitude to those who participated in this survey.

Survey Overview

Goals

March 11th 2011 was a day of tragedy for the coastal communities of East Japan that were hit by the massive tsunami following minutes after the Great East Japan Earthquake. This survey attempts to understand the decisions by people that led to either their safe evacuation and shelter, or failure to find shelter from nature’s terrible power. Assisting Weathernews with the analysis of the survey results are Professor Fumihiko Imamura of the Tohoku University Disaster Control Research Center and Professor Katusya Yamori of Kyoto University Research Center for Disaster Reductions Systems. We hope that our joint analysis will lead to the development of countermeasures against such disasters occurring in the future.

Survey Period

May 18th to June 12th, 2011

Survey Respondents

5,296 residents of Hokkaido, Aomori, Iwate, Miyagi, Fukushima, Ibaragi and Chiba prefectures.

Survey Methodology

Results and accounts of fatalities were collected from Supporters and users of the Weathernew website, Weathernews mobile application and Weathernews Touch smartphone application.

Survey Items & Analysis Results

  1. Time from Initial Quake Until Evacuation

    • Average time until evacuation for survivors was 19 minutes.
    • Average time until evacuation for fatalities was 21 minutes.
  2. Reason for Decision to Evacuate

    • Just 28% of people who evacuated immediately after the quake survived.
    • The majority of people evacuated because of the Tsunami Warning.
  3. Evaluating Evacuee’s Course of Action

    • One in five fatalities was unable to evacuate.
    • The reason for many failures to evacuate was, “I thought it was safe.”
  4. Intended Sheltering Area①

    • Three in four survivors evacuated to a safe location.
    • Three of four fatalities were unable to make it to a safe location.
  5. Intended Sheltering Location②

    • 40% of evacuees were unable to reach high elevation.
    • More than half sheltered in non-designated areas.
  6. Why Couldn’t You Evacuate?

    • 18% of fatalities met with obstacles during evacuation.
  7. Elevation for Tsunami Evacuation

    • Survivor’s average target evacuation elevation was 2.9 stories high.
    • The average target elevation of fatalities was 1.7 stories high.
  8. Getting to and Leaving the Shelter

    • 60% of fatalities were due to leaving shelter and reentering the danger zone.
  9. Reasons for Leaving the Shelter

    • Many left shelter to search for family members.

Detailed Analysis of Results(pdf)