Seismic Hazards: Tohoku, Japan Major hazard event

Question 1

What is the tectonic setting of Japan?

Answer 1

At a destructive plate boundary, the Pacific plate subducts beneath the Eurasian plate and North American plate.

Question 2

What were the causes of the seismic hazard?

Answer 2

The Pacific plate slipped upwards between 5-10 metres so the North American plate was subducted. This caused a large volume of sea water to be displaced.

Question 3

What were the primary (direct) hazards of the seismic hazard?

Answer 3

• The tsunami surged up to 10km inland
• The earths axis shifted at least 10cm
• Scientists estimate that 10 billion tonnes of water hit NE Japan

Question 4

What were the secondary (indirect) hazards of the seismic hazard?

Answer 4

• 800 earthquakes of magnitude 4.5 were recorded following the main earthquake.
• some coastal areas experienced land subsidence where the land dropped by more than 50cm in some areas.

Question 5

What were the social impacts of the seismic hazard?

Answer 5

• 18,000 people dead or missing
• 127,000 buildings destroyed
• Ground shaking caused buildings to collapse and caused petrol pipes to be broken.

Question 6

What were the economic impacts of the seismic hazard?

Answer 6

• Total damages from the earthquake and tsunami of $220 billion.
• Overall insurance losses were $47 billion.

Question 7

What were the environmental impacts of the seismic hazard?

Answer 7

• An area of 500 sq km was flooded
• Lots of pollution up to 6 miles inland.

Question 8

What were the political impacts of the seismic hazard?

Answer 8

• The Fukushima nuclear disaster caused panic selling across the global stock market.

Question 9

How did the tsunami hazard occur?

Answer 9

• The tsunami was caused by the huge displacement of water, caused by the earthquake.

Question 10

What were the short term responses to the seismic hazard?

Answer 10

• 100,000 soldiers mobilized to organise rescue work and provide emergency relief.
• The government shut down the majority of Japanese nuclear power plants, this resulted in Japan’s energy mix being adapted.
• The Japanese Red Cross received £1.5 billion in foreign donations (aid relief).

Question 11

What were the long term responses to the seismic hazard?

Answer 11

• In 2013, Japan upgraded their tsunami warning system.
• The World Bank analysed the responses 10 years on and produced a report.
• Residential houses and commercial buildings built near a sea wall at a port in Mijako.