Hazards Case Study 4: The Tohoku Earthquake 2010 Flashcards
(10 cards)
How is Japan’s place identity affected by natural hazards?
Japan experiences 400 earthquakes a day, and since 2000, 23 earthquakes of 7.0MW have occurred, killing 16000 people, so Japanese folklore is full of references to earthquakes and their effects.
Why is Japan (especially the South East) so vulnerable to earthquakes?
Japan is very densely populated (Tokyo 39 Million, Osaka, 19 Million, Nagoya 9 Million), with the large majority of this being focused around coasts, as mountains populate the central land in Japan.
When did the earthquake occur and where did it originate from?
- It occurred on the 11th of March 2011, just after midday.
- The epicentre was 70km off the East coast of the Tohoku region of Japan, and had a focus 30km deep.
What physical factors affected the severity of this earthquake? (6)
- It was a magnitude 9 earthquake, the largest ever recorded to have struck Japan
- Epicentre was only 70km from the coast, and it was a shallow focus earthquake which meant greater shaking near the surface.
- It lasted 6 minutes
- Triggered a very large tsunami, reaching up to 40.5m in places when it hit the coast.
- 400km of coast fell 60cm, reducing the effectiveness of the 10m coastal sea wall and other coastal defences when the tsunami hit.
- The large floodplains across Japan’s coast allowed the tsunami to travel 10km inland.
What was Japan’s immediate response and how was it effective?
Japan’s seismometers picked up the faster, weaker P waves and sent out a nationwide alert warning people of the incoming S waves. This alert travelled faster than the earthquake for many people.
- following the earthquake, there was a follow up alert for an incoming tsunami, which didn’t reach as many people, but allowed many to escape, with those who got the warning telling those who didn’t.
What was the social impact of the earthquake? (4)
- The earthquake claimed nearly 16000 lives, and injured around 6000 people, with 2/3 of the victims being over the age of 60, and a quarter being over 70. 90% of the deaths were from drowning as a result of the tsunami, and the rest were either crushed by buildings or burnt.
- Dead bodies had to be buried in mass graves, as crematoria and morgues had been destroyed, to reduce the risk of the spread of disease.
- 100,000 children were separated from their families, especially as most children were at school when the earthquake struck. 2,000 of these were orphaned or lost a parent.
- Coastal schools were devastated, with one school losing 24 of 108 students, and 10 of 13 staff.
What were the economic impacts of the earthquake?
- The cost of the disaster is estimated between $200 million and $1 billion, with future costs making up most of the uncertainty.
- Construction continued for over 10 years after the event.
- 45,700 buildings were destroyed, with 143,000 damaged
- 25 million tonnes of debris was created, requiring a costly cleanup operation
- 15 ports in the North-East were directly affected, with 4 being completely destroyed, including in Sendai, the largest city affected.
- 10% of fishing ports were damaged, however most recovered within a year.
- 4.4 million households and thousands of businesses lost electricity, mainly due to Japan’s 11 nuclear reactors being shutdown due to fears following the meltdown of Fukushima Daiichi.
- The Fukushima Daiichi power plant went into meltdown, resulting in a 30km evacuation zone around the plant which is still there to this day.
- Two oil refineries were set on fire, with one taking 10 days to put out.
- Road and train services in the North-East were severely damaged, with 23 train stations being swept away.
- The stock markets in Japan plummeted, with the implications of the power shortages were realised for companies like Sony, Toyota and Panasonic.
What were the political impacts of the earthquake?
- The Japanese government injected billions of yen into the economy, especially the financial sector to bring some stability, increasing government debt at a time when their main goal was reducing it.
- A large movement against nuclear power developed, and concerns over safety standards and regulation of the nuclear industry became a political issue. After a brief period of total shutdown, the plan is to recommission a significant number.
- Several executives of companies involved in the Fukushima Daiichi power plant resigned, and it emerged warnings had been made about the inadequacy of the tsunami defences several years prior.
- The disaster fuelled a global anti-nuclear agenda, with the anti-nuclear lobby in Germany using it to support their arguments against nuclear power.
How is Japan prepared for earthquakes?
- They have effective warning systems in place.
- Aseismic design is commonplace and extremely effective, with skyscrapers in Tokyo being seen to sway from side to side and not fall during the quake
- They are an extremely wealthy economy, with a GDP of $200bn.
- The people are educated and prepared for how to act during an earthquake, with September 1st being designated Disaster Preparedness Day in Japan, where especially children coming back to school after holidays do earthquake drills and learn how to act in an earthquake event.
How is one building in Japan aseismically designed?
The Tokyo Skytree, Japan’s tallest building and one of the largest viewing towers in the world. It is designed with a solid concrete pillar at its centre, detached from the main structure, and instead surrounded by a viscous oil within the outer layer which is then surrounded by the strong outer lattice it is known for. This outer layer is then able to pivot and sway against the liquid during an earthquake event, with the concrete pillar not moving.
