Tsunami Case Study: Japanese Tsunami 2011

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Japanese Tsunami, 2011

Japan was hit by a 9.0 magnitude earthquake on March 11th, 2011, that triggered a deadly 23 foot tsunami in the country's north

Causes:

9.0 magnitude undersea earthquake on 11th March 2011

The epicentre was in the north western Pacific Ocean 130km from Sendai and had a relatively shallow focus of 32km

The earthquake occurred at a destructive plate boundary where the Pacific plate is being subducted beneath the Eurasian plate due to its greater density. The plates had been stuck and building in pressure for around 200 years before it was released.

The Eurasian plates leading edge had been dragged down by the subducting pacific plate flicked back when the pressure was released. This caused the sea floor to move upwards by tens of metres in a matter of seconds and displace the water above leading to the huge tsunami.

Some waves were sent towards Japan's coastline and another set of waves travelled farther out into deeper water in the Pacific.

The tsunami that resulted from the 2011 earthquake was composed of 10 waves; 1km apart and in places 15m high.

Although 40% of Japan's coastline has 10m high protective coastal walls, the waves just went over the top.

The 1st wave hit Japan 24 mins after the earthquake and the last wave hit 3 1/2 hours after the earthquake.

The tsunami travelled as far as 10km inland.

Effects - primary:

Social:

Loss of life - 15,891 deaths (most died by drowning)

Evacuation - more than 163,000 people were placed in shelters around the country

Damage to homes and property - 45,700 buildings were destroyed and 144,300 were damaged.

Around 4.4 million households served by Tohoku Electric Power in NE Japan were left without electricity and 1.5 million households had lost access to water supplies.

Economic:

Agriculture and fishing - around 23,600 hectares of farmland were damaged. The area affected accounts for 3-4% of Japan's rice production. The fishing industry was almost completely destroyed, with 90% of the 29,000 fishing boats in Miyagi, Iwate and Fukishima being rendered unusable. The total damage to Japan's fishing industry was estimated at $11.29 billion

Industry - impacts on businesses such as Toyota, Nissan and Honda

Damage as far as California (2 harbours had major damage)

Environmental:

Flooded an area of approximately 217 square miles in Japan

Fires - at least 357 fires occurred directly after the event, primarily caused by reptured gas lines triggered by the tsunami as it washed ashore - released harmful gases.

Effects - secondary:

Social:

Missing people - in 2015, more than 2,500 people were still reported as missing

4 years after the tsunami, about 230,000 people who lost their homes were still living in temporary housing

Fukushima Nuclear Power Plant

Economic:

Most expensive disaster in human history

By March 2012, 644 companies in Japan had been forced into bankruptcy by the disaster.

Environmental:

Fukushima Nuclear power plant - cooling system failure. Level 7 nuclear meltdown and release of radioactive materials

25 million tonnes of debris was generated in the 3 worst-affected prefectures. Within a year, only 5% had been disposed of and 72% was being stored at temporary sites.

Immediate responses:

Tsunami warning was issued 3 mins after the earthquake

A meteorological agency official appeared on TV urging those affected by the quake not to return home because of the possible tsunamis

The governor asked for Japanese military forces to be sent in to help

59 search and rescue experts, 4 medics and 2 sniffer dogs flew out with 11 tonnes of equipment

8,800 temporary houses in Iwate, 10,000 in Miyagi and 19,000 in Fukushima

Water poured into the damaged reactors to cool melting fuel rods at the Fukushima Nuclear Power Plant

The Japanese Red Cross dispatched more than 200 emergency relief teams to the disaster zone

Shelters set up in schools for those who lived in close proximity to the Fukushima Nuclear Power Plant

NGOs responded e.g. Shelter Box sent 1,500 aid boxes (tents, sleeping bags, bottled water) immediately

Chemical toilets provided for 30,000 residents

91 countries offered aid

Long term responses:

Roads and houses cleared of silt from liquefaction by August and 80% of roads and 50% of footpaths were repaired

Japanese Red Cross gave $1 billion in donations

The Indian Ocean tsunami warning system has been set up to reduce the impact of future tsunamis

116 countries and 28 international organisation had offered assistance to Japan

Water and sewerage restored for all residents by August.