Tectonic shift, reactors and waves of hostility
In recent days, Japan has experienced destruction on an unprecedented scale. But as recovery gets underway, a new threat has appeared on the horizon.
Minamisanriku used to be a port of 17000 people on the North-East coast of Japan. But many are now feared dead after the tsunami left only four buildings standing.
As reporter Judit Kawaguchi tweeted, 'Ten thousand people missing. Horrible – whole town gone. Highways broken into bits, in mud, all mud, all gone.'
But the epicentre of this story lay out at sea, 62 miles from Minamisanriku. Beneath the deep waters of the Pacific, tectonic plates had collided and stress-points had been building for months.
Finally, pressure caused a shuddering realignment of the plates, pushing the sea bed upwards and triggering the tsunami. Seismologist David Wald says this earthquake may have generated energy roughly equivalent to that consumed by the US in a year.
Indeed, the earthquake was so powerful – the fifth most powerful on record – that Italy's National Institute of Geophysics and Volcanology said the earth's axis shifted 25 cm. While the US Geological survey reported the main island of Japan had shifted 2.4 metres east.
And while the full extent of the human disaster becomes apparent - with death, homelessness, food and fuel shortages – fears of another kind grow: nuclear catastrophe at Japan's two Fukushima reactors.
Boiling Water Reactors such as these rely on water to keep the core cool.
If the water stops flowing, the core overheats and the water turns to steam.
This then generates huge pressure inside the reactor vessel, a sealed container, causing an explosion. The excess heat also causes the core itself to melt, heightening the danger of radioactive materials entering the environment.
The government's chief spokesman, Mr Edano, claims there's no immediate threat to human health.
But not everyone is so sure. Reiko Takagi lives in Iwaki, 18 miles from the No.1 plant. 'Everyone wants to get out of the town,' she says, 'But the roads are terrible. It is too dangerous to go anywhere. But we are afraid that winds may change and bring radiation toward us.'
Japan suffers from its precarious geological setting. Its islands formed where one great plate of the Earth's crust, the Pacific plate, slides under the Eurasian and Philippine plates. The collision is part of the 'Ring of Fire' of earthquake and volcanic activity around the Pacific Ocean.
Japan believes it's the nation best prepared for earthquakes. But as Minamisanriku reminds us, in the face of nature's absolute power, even the best laid plans can crumble.
- 'There are pluses and minuses wherever you are in the world. Geography alone would never affect where I live.' Discuss.
- 'Humans are clever but they'll never tame nature.' Do you agree?
- Take a look at some online photos of the port. And then create a graphic/picture/collage called 'Minamisanriku – after the wave.'
- Research how nuclear reactors work. (See 'Become an expert.) Consider their history, their place as an energy provider, the dangers and the safety precautions currently used. Then, in a short piece, answer the question: 'Are nuclear reactors worth it?'
Some People Say...
“I'd never live on the edge of a tectonic plate.”
What do you think?
Q & A
- How does this earthquake compare with the one that hit Christchurch, New Zealand?
- It was 8000 times bigger. As Dr Roger Musson said, 'This is a rare event, something you would expect only once in a decade. Instead of concentrated destruction as you had in Christchurch, there will be damage over a very wide area in the north-east of Japan.'
- Has the UK ever experienced this?
- The largest tremor in the UK was in 1931, off the coast of East Anglia. But the Japanese quake was 16000 times more powerful. We live in the middle of a plate so we're safer.
- And the world will always be unstable?
- 'We live on a dynamic planet,' says seismologist Davie Galloway, 'and the Earth's crust is made up of nine major plates which can bang into, move away from or shift under each other, at about the same rate as finger nails grow.'