Case Study - North East Japan Earthquake and Tsunami (2011)

The earthquake off the coast of Honshu, Japan's largest island, on 11th March 2011, was the most powerful earthquake ever to hit Japan. It recorded 9.0 on the Richter Scale, also making it the fifth most powerful earthquake of all time anywhere in the world.

Facts

The quake struck on the 11th March 2011.
The earthquake measured 9 on the Richter scale.
The epicentre was 130 km from the coast of Sendai in North East Japan.

Causes

Japan lies in many plate boundaries.
The earthquake was caused by a destructive plate boundary: the Pacific plate was sining under the Eurasian plate.
The plate boundary is known as the Pacific Ring of Fire, an extremely active tectonic area.
The ocean trench and the subduction zone were in the Pacific Ocean.
As the Pacific plate slipped under it released an enormous amount of tension at the focus. This has been building up over centuries and caused massive primary seismic waves.
The more dangerous secondary seismic waves made their way towards the easter side of Japan.
The shock waves also caused a tsunami.
There were 508 aftershocks of magnitude 5, 6 and 7.

Effects

Environmental

The earthquake shifted the earth's axis by 25 cm.
The earth has changed shape as a result of the earthquake.
Japan's north-east coast moved 3 metres out to sea.
Parts of the coast dropped over 1 metre, causing tsunami defence walls to become smaller.
The earthquake ripped down the infrastructure in the area affected.
The Fukushima nuclear power plant was affected by both the tsunami and the earthquake. Meltdown occurred.
Liquefaction appeared in the cracks in the ground. Liquefaction is when water is pushed up to the surface and through the cracks, like a sponge releasing water.
10 billion tonnes of water spread out across Japan after the tsunami.
At Sendai the water travelled 10 km inland.
The stress released in the 2011 earthquake may trigger a bigger earthquake further south in Japan, in places such as Tokyo.

Social

15,000 people died and 5,000 people were missing, presumed dead.
The Fukushima nuclear plant was affected and sent out radiation. Some people were evacuated from the nearby area.
The airport at Sendai was destroyed.
The temporary shelters in Sendai were full.
Huge areas were without power.
Services such as schools and hospitals were shut or destroyed for a long period of time.
Mountain residents worried about the corpses being swept up the rivers in the water.
Hawaii had to evacuate people living near the sea. Luckily no one died.
In Minamisanriku 50% of the population died and 95% of the buildings were destroyed.
People had to rebuild their lives; many people had lost everything.

Human Response

The immediate response to the earthquake was automatic warnings to the Japanese people, on mobile phones and on television.
There was a one-minute warnings for earthquake and a 20-minute warnings for tsunami.
The Hawaii Pacific Earthquake facility also sent warnings to countries surrounding the Pacific, and as a result only one person died in a country other than Japan (on the California coast).
More data was collected from this earthquake than from any other disaster to date.
The Japanese military were immediately on the scene, clearing debris in the towns that had been demolished.
Aid was sent by different countries to help ease the impact of the disaster. Rescue groups were also sent.
Every school and business had performed earthquake drills and these saved many lives.
The Japanese people remained calm and waited for help; there was not a mass panic.

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