Mechanics of Earthquakes
On March 11th, at 2:46PM, three giant earthquakes occurred along the edges of the tectonic plates at the ocean bottom on the Pacific coast off the Tohoku (literally meaning “northeast”) Region. Initially it was assumed that there was one big earthquake, but with the analysis of seismic movements, scientists confirmed that there were indeed three gigantic earthquakes occurring in tandem within six minutes of each other, destroying the earth crust in the length of approximately 500 km (310 miles) in length and 200 km in width, similar to the earthquakes off Sumatra in December 2004. The monstrous tremor continued for more than 5 minutes in many locations, which was unprecedented, with a combined magnitude of 9.0. It moved, for example, Oshika Peninsula to the east of Sendai by 5.3m (17’4”) to east-southeast and sank it by 1.2m (47”); and the shift in the land mass increased the oscillation of the earth’s rotational axis by 17cm (6.7 inches) and made the day 1.8 microseconds shorter. It was also accompanied by horizontal sheer displacement of 20m (65’7”) or so, and more deadly, 3-4m (10-13’) of vertical displacement of the ocean bottom, which produced tsunami waves, which reached all the pacific coasts of Japan and as far away as Hawaii and Chile, and other countries.
Casualty
As of today (March 30th), we have counted 11,232 people confirmed dead, of which 8,799 were identified (and 8,412 were taken back by the families), and 16,361 people reported missing. (This figure of course does not include those who are not “reported” missing; i.e., if the entire family / household is wiped out, there is nobody reporting the missing.) There are still 174,367 people living in 2,065 temporary shelters.
Japanese law requires that the dead be cremated in principal, but the gov’t has declared an emergency measure allowing for regional gov’ts to have them interred if consented by the next of kin. The process has started in the coastal communities where the municipal cremation facilities were damaged by tsunami or are inoperable due to a lack of fuel.
As the debris are cleared away, they are sure to find many more bodies in hundreds and thousands in the tsunami hit regions. And still, there will be many whose bodies will never be found as they are carried out to sea, which will pose a significant emotional stress to the survivors
Tsunami
As you may know, the great majority of those who died or are missing were victims of giant tsunami waves that came about 15-30 minutes after the initial shock of earthquakes. In most locations, the government had predicted the maximum possible tsunamis to be 4-6m (13-20’) tall. In reality, the waves reached and destroyed 10m tall levees and washed over the rooftops of school buildings that were 3 to 4 floors high. There are water marks at 14-20m (46’ – 65’7”) above ground on structures still standing. When a wall of water hit, its destructive force was enormous; all the wooden structures were washed away and only concrete structures remained standing, but their windows and doors smashed. Even parts of anti-tsunami levees were destroyed and pieces were “carried” in-land by the force of water. A tsunami wave, when rushing on shore, is not just a volume of water; it carries debris, cars, trains, fishing boats and what not, which become a massive group of projectiles that flow around destroying everything on their way, and take victims far out to sea when it recedes. The only way to survive a tsunami is to get up to a higher ground before it reaches you.
In tsunami hit communities, there are reports that many people in the coastal community did not rush to high grounds after the tremor because they had been accustomed to the “crying wolf” of tsunami alarms, and had a false sense of security with massive “state of the art” anti-tsunami levees built along the shorelines, which were in a sense proud symbols of technological progress and political maneuvering (in pork barrel project budget). On the other hand, many of the victims had put on layers of clothing, and had backpacks on full of underwear, food items, cash and bank books, and the official seal (which the Japanese use for transactions instead of signature), indicating tsunamis caught up with even those who were fully aware of the urgency of leaving the coastal areas.
Depending on how far the epicenter is, tsunamis take time to reach the shore, anywhere from 10 minutes to 2 hours to an entire day. If you have felt a strong earthquake and if you are close to the sea, you should drop everything and go for a higher ground. (The tragedy around the Indian Ocean in December 2004 was caused by the distance; no one felt the earthquake, and without a warning system along the sea side communities, people did not suspect anything unusual until tsunamis arrived the day after the earthquake that triggered the massive movement of water on the other side of the ocean. The only premonition they should have noticed was that, oftentimes before a massive tsunami reaches the shore, the water recedes first far out off the coast. Unfortunately in those resorts, people thought it was a great opportunity to go out to see fish stranded on the sea bottom.) In reality, however, there were elderly, who had mobility problems. There were people who wanted to go back home to see if their family members were alright after the big shaking. Those who were driving may have gotten stuck in traffic in narrow streets. Those people wasted the precious 15 to 30 minutes they had after the initial earthquakes.
In schools after the earthquakes, children were sometimes evacuated to a higher ground behind them; sometimes led up to the roof of their own buildings. One reported story has it that, even after having evacuated to the rooftop, a teacher was listening to the radio report of the height of tsunamis coming to a nearby fishing village, and noticed that it was much higher than the height engineers had told the town people to be the highest possible. He then alerted the children to go further out, away and higher, which saved many lives.
In some cases, people were witnessed literally riding over the torrent on tatami mats, floating cars, or even inside their own houses. But in the end, most of them perished as they were pulled into the water, tossed upside down, or hit hard at standing structures. Survivors say the pull of the water current was so strong that they clung to whatever they could reach to literally for dear life. Some survived like a James Bond movie, but most simply drowned quickly. We still do not know how many bodies were carried out to sea that day.
We hear news of towns of population 10,000 to 15,000 people being able to account for only 5,000 or 7,000. The rest is presumed dead either buried under the debris or lost to the bottom of the sea. In fact an account of a woman rescued by a helicopter has it that she saw hundreds of bodies and fragments thereof floating around her as she was lifted up. It must have been a hellish scene. Japanese TV and magazines show only sanitized pictures; i.e., never a corpse appears in a published picture out of respect for the victims. I wonder about the traumatic effect on small children.
Japan has built so many “tsunami evacuation centers” along the coast. However, with tsunamis of this magnitude, all of these centers look too small, too short, and too weak. The ubiquitous concrete levees destroyed the beautiful seashore sceneries, cut-off the fishing community from the sea, and still did not protect the communities as planned. Many of the communities hard hit this time have a history of tsunami damages in the past so many centuries; yet the government as well as the local people believed in the power of engineering over the power of nature; causing devastation again. The only way not to repeat the mistake seems to rebuild the community on a higher ground, somewhat away from the waterfront, and have only the fishing industry related structures and park spaces (and the tsunami warning system) near the water. A 1000-year tsunami may not come again next year, but the decision they make this year could bring great sorrow to the descendants of the next generation or one after that.
Fukushima Daiichi Nuclear Plants – What Happened and What Is Happening
Of the six reactors at Fukushima Daiichi Nuclear Plants, approx. 230km (143 miles) north-northeast of central Tokyo, the units 4-6 were under regular maintenance, and the reactors were not running at the time of the earthquakes. The units 1-3 were running, but the automatic shut-down mechanism worked to insert the control rods into the nuclear fuel to shut off the fission reaction within the reactors. However, the temperature of the fuel rods must be under constant control by way of circulating coolant water, which rely on electric pumps. When tsunamis hit the area sometime afterwards, which were at 14m tall while the facility was designed with the maximum tsunami design height of 5.7m, the compound received physical damages as well as water damages on the electrical systems. The emergency back-up generators as well as the reactor buildings were installed with the grade level at around 10-13m above sea level.
The supposedly “fail-safe” back-up cooling systems, thus, all failed, and, while the nuclear reaction itself was somewhat controlled, the fuels kept releasing what is called decay heat. Tokyo Electric Power Company (TEPCO) immediately connected fire-fighting pumps to directly introduce sea water into the reactor vessels (the inner-most casing of the reactor fuel rods where steam is generated) to keep fuel rods from overheating. But they suspect that in some reactors, the water level within went so low that much of fuel rods were above the water level, causing overheating, damaging the fuel rod casing (zirconium alloy tubes), and raising the radioactive water vapor pressure inside.
Another menace was the spent-fuel pools, which are built above the reactors. Spent fuel rods must be taken out of the reactor, and be submerged in water in these pools for 4-5 years to really cool them down before they can be stored in “casks” for permanent disposal. This requires again moving coolant water. These pools are less well protected than the reactors; the only shield above the pools is only one layer of the building walls. As the electrical system failed, the water circulation stopped, raising the water temperature, and eventually evaporating it to expose the, though spent still radioactive, fuel rods to air.
There were hydrogen explosions in units 1 and 3. When zirconium gets very hot, it reacts with oxygen, releasing hydrogen. As the pressure within the containment (two-meter thick concrete structure housing the reactor vessel) rose to a dangerous level, TEPCO opened valves to release some steam inside. Hydrogen was released with it to the space above the containment but inside the building envelope. At some point, the hydrogen concentration was at such point that some electrical spark or something ignited it and caused explosion.
These explosions provided sensational TV pictures of mushroom clouds raising above, which sent alarm to the entire world. Very important facts here are that the explosion was not nuclear explosions, but hydrogen explosions, and that they occurred above the concrete containment, and it is unlikely (well, at least TEPCO and some scientists say) that they damaged the containment or the reactor vessels. Though a critical state continues, these explosions themselves were not catastrophic events.
