Tohoku Earthquake and Tsunami : Japan, 2011

Tohoku Earthquake and Tsunami : Japan, 2011

1. Location

   • on average, earthquakes occur every 5 minutes
   • 20% of the world's earthquakes that are Richter 6 or over occur in Japan
   • More tsunamis than any other country

2. Cause

   • Pacific Plate subducts under Eurasian Plate 8cm a year - snags as it goes. Pressure builds, Pacific plate buckles.
   • Slow motion collision at subduction zone at a convergent plate margin
   • 480km stretch of Pacific plate broke free and surged beneath Japan
   • Eurasian plate lifted by over 9m
   • Tsunami: 6m upward seabed surge at the epicentre. As it approached Japan, shallower depth slowed swell and piled water into 10m high wave
     • 40m in some parts

3. Nature

   • Earthquake
     • p waves 6km a second
     • 9 Richter scale
     • 2 million times more powerful than the Hiroshima bombing
     • 5th strongest ever recorded globally
     • Affected entire Northern half of Honshu - most severe in Tohoku, NE coast
     • 500 aftershocks between Richter 5 - 7
     • Epicentre 100km from coast
     • Focus 6km deep, 25km below Pacific Ocean
   • Tsunami
     • Travelled at 800km/h
     • 100km wave length
     • 1m high, until it reached Japan and piled into a 10m high wave
       • 40m in some parts
     • Scientists estimate 10 billion tonnes of water hit NE Japan

4. Impacts

   • Social
     • Primary
       • 300,000 lost their homes
       • Minamisanriku wiped out by tsunami
       • 16,000 died - 90% killed by tsunami
       • 80,000 left homes within two days
       • Fukushima reactors overheated, 20km evacuation zone due to radiation explosions
       • Train systems paralysed, as was Sendai airport
     • Secondary
       • 3000 still missing
       • Female lifespan fell 0.4 years in 2011, believed to be due to this event
       • In one residential home: 11 elders died due to low night temperatures below -4 degrees Celsius, broken heating and the dampness of floodwater
         • Hypothermia
       • Exposure to radiation - radiation 'hot spots' detected around Tokyo 200km away
       • many killed by fire, shock, exposure
       • 250 plant workers faced serious illness due to conditions
   • Environmental
     • Primary
       • Eastern Fukushima - 2 million people - fears of water and food supply contamination - local produce avoided
       • 60,000 acres agricultural land contaminated
       • 60,000 tonnes of radioactive water flooded reactor basements
       • 5 million tonnes debris swept into Pacific Ocean
     • Secondary
       • Fukushima - 15% locations tested above level as contaminated as Chernobyl
       • Bottom dwelling species of fish like cod and sole may be inedible for 10 years, research suggests
       • 5 months after meltdown - radiation traces in tuna caught off californian coast
       • debris swept 4000 nautical miles
   • Economic
     • Primary
       • Toyota lost over 1/4 of a million of its veicles
       • Japan without nuclear power for first time in 40 years
       • £20 billion insurance