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Posted by wmmbb in East Asia, Environment.

The movement between the tectonic plates happens without warning. In the case of the Japanese quake the epicentre was off shore which meant it generated a tidal wave that speed across the ocean as the speed of jet aircraft – reported to be 800 kilometers per hour.

The earthquake is reported to be the seventh largest on record. The full extent of loss of life and destruction have not yet been assessed. The tsunami dramatically builds in height and destructive impact as it races up the incline of the shoreline.

At The Independent, David McNeil provided a summary of the consequences:

Japan’s most powerful earthquake in centuries struck yesterday, triggering fires, deadly 10m (33ft) waves and tsunami alerts across at least 20 countries.

This morning, the death toll was estimated at more than 1,300, most of them drowned – a toll which looks sure to rise significantly in the coming hours and days with many thousands reported missing. And fears about potential nuclear disaster were raised when emergencies were declared at two plants. One was planning to release radioactive vapour to ease pressure on the reactor.

The massive 8.9 magnitude quake hit the north of the country 230 miles (373km) from Tokyo. Near the epicentre and in the worst-hit Miyagi Prefecture, houses toppled over or collapsed, burying dozens of people. Extraordinary television images showed a tide of muddy water sweeping cars and houses across open land at high speed.

The day was punctuated with shocking images of devastation and public paralysis. Police reported a ship carrying more than 100 people was swept away in the giant tsunami that crashed into the country’s north-east. A bullet train was reported missing on the line connecting Sendai and the nearby city of Ishinomaki, while later another train was feared to have been swept away. Two other trains were also missing.

A major blast rocked a petrochemical complex in Chiba, outside the capital. The earthquake shut Japan’s busiest main international airport, brought the capital’s entire rail network to a halt and sent thousands of office workers spilling out on to the streets.

In Miyagi, fire broke out at the Onagawa nuclear plant and at least three other plants were automatically shut down. The government declared a state of emergency – Japan’s first – at the Fukushima No 1 plant after reporting that its cooling system had failed. A report by Kyodo News said one reactor in the plant “could not be cooled”. A safety panel said radiation levels inside the reactor were 1,000 times higher than normal, the agency added later. Residents living within 10km of the plant had been told to evacuate the area. An emergency was later declared for its sister plant at the facility.

Water reportedly spilled from pools containing fuel rods at the world’s largest nuclear power plant, Kashiwazaki-Kariwa plant in Niigata Prefecture, but there were no reports of radioactive leaks. News of the quake left the International Atomic Energy Agency scrambling for details about the fate of Japan’s network of reactors, which supply the country with a third of its energy needs.

One immediate long term consequence of the earthquake and its associated ramifications will be to call into question the wisdom of relying on nuclear power especially in areas prone to severe seismic activity. Both Japan and California fit into the category.

As events are unfolding it is not clear that the design features of the some of the nuclear plants have stood up to hard test provided by nature. At one plant there are reports that the roof has fallen in, the sides of building have collapsed, and the exclusion zone has been widened to 20 kilometers. In the extreme case of reactor meltdown, seawater can be pumped to cool the core of reactor but at the cost of ending the serviceability of the plant. The nuclear reactors are operated by private companies who will be loath to take the final solution, and the Government will have concern about providing long term alternative sources of power generation, if that were to happen.


Richard Black for the BBC reports on the “huge explosions” at the nuclear reactors. He wrote:

Analysts say a meltdown would not necessarily lead to a major disaster because light-water reactors would not explode even if they overheated.

But Walt Patterson, of the London research institute Chatham House, said “this is starting to look a lot like Chernobyl”.

He said it was too early to tell if the explosion’s aftermath would result in the same extreme level of radioactive contamination that occurred at Chernobyl.

The explosion was most likely caused by melting fuel coming into contact with water, he told the BBC.

The Seismic Monitor (via IRIS) gives a current indication of the extent and intensity of earthquake activity, but the recording of earthquake activity does not give the full story. The Christchurch Earthquake was not as intense as others have been but it struck a populated area built on alluvial land. Much of the devastation of the most recent Sendai Earthquake will have arisen from the Tsunami it generated, not to mention the nuclear power reactors that were built in an earthquake prone area.

ABC News reported on Sunday, 13 March  via AFP:

Japan’s earthquake, one of the largest ever recorded, appears to have moved the main island by about 2.4 metres, the US Geological Survey (USGS) says.

Friday’s magnitude 9 quake unleashed a terrifying tsunami that engulfed towns and cities on the east coast of Honshu island, destroying everything in its path.

The quake and its tectonic shift resulted from “thrust faulting” along the boundary of the Pacific and North America plates, according to the USGS.

The Pacific plate pushes under a far western wedge of the North America plate at the rate of about 83 millimetres per year, but a colossal earthquake can provide enough of a jolt to dramatically move the plates, with catastrophic consequences.

“With an earthquake this large, you can get these huge ground shifts,” said USGS seismologist Paul Earle.

“On the actual fault you can get 20 metres of relative movement, on the two sides of the fault.”

He said similar movements would have been seen for Chile and Indonesia.

Kenneth Hudnut, a USGS geophysicist, said experts read data, including that from global positioning systems, to determine the extent of the shift.

“We know that one GPS station moved, and we have seen a map from GSI (Geospatial Information Authority) in Japan showing the pattern of shift over a large area is consistent with about that much shift of the land mass,” he told CNN.




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