Tohoku earthquake

• Factors that contributed to the 2011 Japan disaster

  • Physical factors
  • Human factors
• Japan's location


  • Located on the eastern edge of the Eurasian plate, adjacent to the Pacific plate
  • Pacific plate is moving westwards, towards the Eurasian plate
  • Pacific plate dips beneath Japan
• Plate boundaries in the Japan region

  • Eurasian, Pacific and Philippine plates meet
  • Okhotsk plate to the north
  • Complex make-up of the eastern part of the Eurasian plate with several large fault lines
• 7.2 (Richter Scale) earthquake on the plate boundary


  Wednesday 9 March 2011
• The 7.2 earthquake


  Put extra strain on an area of existing pressure build-up along the margin, leading to a 480-km stretch of the Pacific plate breaking free and surging underneath Japan
• The Eurasian plate (on which Japan is situated)

  Shifted 2.4m eastwards and was simultaneously lifted upwards by over 9m
• The consequence was the 9.0 (Richter Scale) Tohoku earthquake on 11 March, rated as the fifth most powerful ever recorded globally
• Richter scale


  Each point on the scale has 10 times the energy of the point below
• The 9.0 earthquake released around 1000 times the energy of the 7.2 earthquake two days previously, equivalent to around 600 of the Hiroshima atomic bombs
• Tsunamis


  • Japan experiences more tsunamis than any other country
  • Factors determining tsunami height and destructiveness: scale of earthquake, volume of displaced water, topography of sea floor, natural obstacles
• The tsunami was concentrated on a limited stretch of coastline around Sendai
• Tsunami formation


  1. Sudden vertical push of water above the earthquake epicentre

  2. Water surged away in all directions at 800 kph

  3. Wave speed and height determined by ocean depth - shallower water slows lower part of wave, causing wave to build up higher
• The tsunami wave was believed to have reached 40m in some places, completely overwhelming for people and environments
• Evacuation and coping challenges

  • Loss of communications (landlines, mobile phones, electricity)
  • Lack of emergency workers and supplies
  • Inadequate evacuation facilities leading to hypothermia, illness, and deaths
• Within 10 days, an estimated 452,000 people were living in evacuation facilities, most of which were inadequate
• Damage to infrastructure (roads, railways, airports) severely impeded transport and delivery of aid
• Scavenging


  People forced to scavenge for food and provisions from wreckage, despite health risks and cultural norms against it
• Even in an MEDC like Japan, many people had to become looters to stay fed, even at a limited level
• The extra difficulty for the Japanese was their culture of pride - reputation in society is very important, and being caught scavenging could blacken one's name and diminish the family
• People were scavenging in the streets to try to find food for their families. They took what seemed like waste food from devastated supermarkets even though there were health risks from thawed frozen and out of date products.
• People found themselves without money, food and other resources, and their homes had been washed away and the cash machines were out of order.
• The extra difficulty for the Japanese in this awful situation was their culture of pride. Your reputation in society is very important to the Japanese. Just to be caught taking food or other crucial resources could blacken your name and diminish your family.
• Even in an MEDC like Japan, many people had to become looters to stay fed, even at a limited level.
• Even those lucky enough to be in rescue centres were not necessarily fed enough in terms of quantity, calories or nutrition.
• People felt genuine shame at what they were doing and, whilst some did speak to foreign press, they refused to give their names or to have their photographs taken.
• The local authorities found themselves under massive strain. The rules on burial procedures had to be relaxed to permit the burial of bodies without prior cremation, not the normal ritual in Japan, but essential on health grounds.
• Emergency workers coming to the affected north-eastern part of the country had insufficient knowledge of the situation, inadequate equipment and basic supplies like food, clean water and medicines.
• Whilst many roads in the north-east region were devastated, quite a few remained open, but only emergency vehicles were allowed to use the roads, so preventing food supplies, fuel and other aid from being driven from Tokyo.
• Finding petrol and diesel became impossible; people siphoned it from vehicles damaged in the tsunami and tried to find lost bicycles in the piles of wreckage.
• People struggled to find missing friends and relatives in any way they could.
• Nevertheless, many people refuse to criticize the local or national authorities, realizing that the sheer scale of the destruction had made delivering aid a truly mammoth task.
• The Fukushima Daiichi nuclear plant disaster brought on by tsunami damage was one of the most serious civil nuclear accidents to date. Key safety systems failed, causing serial explosions and increasing releases of radiation.
• Four of the plant's six reactors were in trouble; higher than normal radiation levels were registered as far away as Tokyo (220km) but were not considered serious.
• Caesium and iodine isotopes have been found near the plant, and water and crops were prevented from entering the food chain.
• Local people (within 20km of the plant) were evacuated, and others left of their own accord.
• Compared with Chernobyl's disaster in 1986 (Ukraine), only 10% as much radiation was released.
• A report published in the Proceedings of the National Academy of Sciences in November 2011 stated that radioactivity levels across much of the North Eastern region of Japan remained higher than that considered safe for farming, despite the fact that earlier testing had showed that harvested crops contained levels of radiation well below the safety limit for human consumption.
• The western coastal plain region measures safe levels; it was largely protected from the worst of the radioactive fallout by the intervening mountain ranges.
• Rice exports from this region to the rest of Japan have been banned, though some may have been consumed locally. Scares over radiation levels in green tea, mushrooms and beef have occurred.
• All other nuclear plants will be strength-tested for tectonic movement. Moreover, the Japanese authorities have been made to think about the country's future energy mix. Current policy is to increase from 30% of power being nuclear-generated to 50%, but now the likely future trend is away from nuclear, perhaps even to go nuclear-free in such an active tectonic zone.