Japan’s Tsunami: How It Happened

It was tragedy on an extraordinary scale. A quake so powerful, it knocked the earth off its axis. Tens of thousands dead. The whole of Japan shifted three meters out to sea. Parts of the coast dropped over a meter. What were the forces that came together to create this horrifying disaster? A team of scientists is investigating. “Never before have we had such a surplus of data. There are no mysteries in this earthquake. We know exactly what happened.” experts say. Japan’s coast lies in ruins. Incredibly, it could have been even worse. This is the untold story of how science save lives. And how scientists piecing together exactly what happened.

Professor Roger Bilham is a world-leading earthquake expert. He is in Japan to witness the immediate aftermath. “So we are flying right over the coast right now. And much of the coast has sunk about a meter. The scent to the damages is truly amazing. Tsunami picked up everything in its power. Cars, houses, warehouses, tumbled relentlessly in land on and on and on. One of the things I had like to see is exactly, how far it went, what kind of debris again it left behind of the gigantic tsunami.” said Bilham. Bilham is the first geologist to conduct an aerial survey to the damage.

Every detail at the disaster has been recorded by seismometers, strain gauges and tide gauges, allowing experts to analyze exactly what happened. But this was the first and foremost, a human tragedy on an unimaginable scale. “I wanted to find out desperately so I came here.” said one of the tsunami’s victim. It ripped away much of Japan’s infrastructure. One of the world’s most developed nations brought to its knees.

As rescue workers picked through the debris, Bilham and other scientists around the world take on the challenge of understanding the massive earthquake in the hope of one day avoiding such loss of life. The source of the disaster laid 100 kilometers off the coast. Beneath six kilometers a water, the earth was distorting, a vast slow-motion collision. The earth’s crust is made up of several continents sized slabs of rock -tectonic plates. Japan lies on a boundary between these plates. The Pacific plate is running into it eight centimeters a year, about the same speed your fingernails rub. The Pacific Plate dives underneath it, snagging and catching as it goes.

The plate that Japan sits on compresses and buckles under the strain. Over decades and centuries, immense stress began. “The energy that drove this earthquake, building up for a couple hundred years, caused by the movement of the Pacific plate towards the rations plate. Think of it as a giant elastic band that wide up for about two hundred years.” Bilham explained.

On March 11th, 2011 at 2:46 p.m. Japanese time, the stress is reached it’s breaking point. “Lot of energy released on an earthquake in this is really huge and you have to measure it in large units. If you take the atomic bomb that devastated Hiroshima, this event was probably two million of those really huge amount of energy.” Tom Jordan (Director, Southern California Earthquake Center) said. Shock waves radiated out. The fastest known as “P waves”, travel that six kilometers a second.

Japan’s detection systems picked them up instantly. Within seconds, before anyone realized what was going on, automatic warnings flashed across the country. A computer-generated announcement even interrupted a Japanese Parliament broadcast. By the time the warning system kicked in, the coastal city of Sendai just 230 kilometers from where the earthquake originated, was shaking. The slower but more destructive shockwaves called “S waves”, had now arrived. This waves travel at three kilometers a second, they through northeast of Japan into chaos.

As the shockwaves raced outward, a 150 kilometers southwest to the epicenter, they slam past Fukushima Dai-ichi. An aging nuclear power station housing six reactors and generating four-and-a-half gigawatts of electricity for the local grid. This footage from a town near the reactor, give some idea that the earthquakes power. Japan’s warning system that automatically shut down the reactors. Cooling them would take time. “When you think shut down, the thing up you know, the dangers gone because it shut down, but the reactor core was still extremely hot. You know, if you have a pan in the oven, and you shut the oven off, that even continues to heat inside, even after you have turned it off.” Jim Walsh of (MIT Security Studies Program) added. After shutdown, emergency diesel generators kicked in to pump coolant through the reactor cores. Fukushima survived the earthquake intact.

But there was one big problem, it stands just meters from the sea. 11,000 kilometers away, the Pacific Tsunami Warning Center in Hawaii staff got emergency pager messages. Within 10 seconds at the earthquake starting, its effects were already being monitored around the world. “Japan has lots of seismologists so, there was a lot of information fast. So, the earthquake was still going on when we got up page.” said Gerard Fryer of (Geophysicist, Pacific Tsunami Warning Center).

First indications, a magnitude around seven, but as day to flooded in the figures started to climb.. 7.5.. 7.7.. up into the 8. “The immediate reaction everybody was not right. Because in the history of Japan, there has never been an earthquake larger than 8.4.” Gerard Fryer added. “It really heightened our intensity of what we were doing, because we knew we were dealing with something very big and something that could affect the whole Pacific Basin.” Charles McCrerry of (Director, Pacific Tsunami Center) explained. “We realized -Oh! this is it! and then immediately you realize, this is horrible for Japan.” Gerard Fryer added.