Japan is subject to two kinds of earthquakes: one caused by ruptures at plate boundaries (and the motion is a side-to-side swaying), or an epicentral earthquake (where the force comes from beneath). The former is more common, happening every 200 years or so (such as the great kanto earthquake of 1923) and the latter, which the Hanshin earthquake of 1995 belongs to, has a cycle of a few thousand years. The Tokyo was due for a big 7~8 magnitude earthquake within the next 30 years, but no one expected one this big – even though it is the former type, this size earthquake only happens every thousand years or so.
This earthquake, said to be the world’s fifth-strongest, was the result of a rupture near the boundary of the Pacific and North American plates, and the Pacific plate slipping under Japan at the Japan trench. In the process, a displacement of about 20 meters occurred and a fault a few hundred kilometres long was created. The next morning, Niigata and Nagano prefectures, almost on the other side of the island, were hit by a 6.7 magnitude earthquake, though whether that had any relation to the Friday earthquake is difficult to determine.
The extent of the damage is, well, incredible, and the video footage shown round-the-clock on the news is horrific. The death toll is over 700, and deaths & persons unaccounted are estimated at over 2900. After the tsunami, as water was draining away vortices started appearing engulfing boats and anything else in its war paths typical of those you only see in Hollywood action movies. Sendai airport was flooded with water turned to sludge so quickly and so completely that even the news commentator had to note that this was NOT the sea but the aiport. Huge settlements, like that of minamisanriku, with a population of 17,000 have completely been wiped out, with the exception of the hospital, and still over 10,000 of those are missing. Footage of houses being pushed by strong water currents against metal structures conjuring up thoughts of a shredder. People waiting on top of hospitals for help, spelling out SOS. Footage of a boat actually ON TOP of a house.
It has to be noted that the area hit, with the exception of Sendai, consisted a lot of countryside, which means there were many low, less sturdily built houses.
A friend of mine in Tokyo used the lovely imagery of shaken but not stirred, as Tokyo has been able to avoid grave damage. South of Tokyo, damage seems to be extremely limited, here in Nagoya the earthquake felt was at a magnitude of about 4. Authorities are warning people in Tokyo to stay alert, and not to think that the worst is over.
And the list goes on. Somehow old people come out of their houses with an occasional smile.
As if all of this wasn’t bad enough, the nuclear power plants are causing a stir. First of all, it really puts the issue in perspective of WHY would a country that is right on top of a heavily-active faultline still have active nuclear power plants (one friend mentioned that it’s partly a military move – you’re much less likely to attack a country with active nuclear power plants). Furthermore, the issue of what is actually going is being talked down and not all questions are being answered.
The way nuclear power is generated is through a nuclear fuel element, immersed in water, getting hot. The water carries the heat away, and the steam this generates is used to turn turbines and thereby generating electricity. If there is not enough water to cool the core down, too much steam is generated and this way the core can melt through the bottom of the reactor. There is a containment unit at the bottom to prevent any more damage, but if this unit does not work, leakage could flow from the bottom.
The past two big disasters involving nuclear plants were 3 mile island in the US – danger level 5, but minimal damage as the containment systems held – and Chernobyl, which was danger level 7 (the top) but this was the result of an explosion into the air rather than a molten core. The power plants here are currently at danger level 4.
In the Fukushima Daiichi (Fukushima 1, as there are 2 power plants in Fukushima) case, the water system cooling the core has stopped working, and despite the owner of the power plants, called Tepco, talking down the danger from the nuclear power plants, the Japanese Nuclear Power commissioner said that ‘a meltdown is possible, but officials are checking’… whatever that means. The 1st of the 4 reactor systems’ cover blew up yesterday around 15:36, before which radiation emission was detected at 1,015 microsieverts (the equivalent of the amount of radiation an ordinary person receives in one year) and after the blast this number significantly decreased. Radiation inside the control room of the reactor reached 1,000 times more than normal, and near the main gate about 70 times more than normal. So far, 190 people have been exposed to radiation, or which 19 have needed immediate assistance. Around the Daiichi plant they put an evacuation zone in place of about 20km, and a 10km one around Daini (the 2nd of the power plants). And this power plant is about 200km north of Tokyo... worrying?
The most recent development is that the 3rd reactor of the Daiichi plant is now emitting radiation levels of 1557 microsieverts…
That’s all I know so far… if there’s any other major developments, I will let you know.
1 comment:
Thanks for giving a more detailed look than we can get from normal news. Hang in there!
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