Meltdown: Preface-Day 1

Before the disaster, Fukushima was known as a lush farming area that supplied produce, dairy products, and seafood to the rest of Japan.

In real time, it’s impossible to know whether an earthquake is its own event or a precursor of something bigger on the way.

Like hundreds of thousands of others who lived along the coast of Tohoku, Ryoichi was at the start of what would be a long, terrifying ordeal. By nightfall, much of his hometown, including his own house, would be swallowed by waves.

But miles beneath the soil and sand, the mountains and oceans, Earth’s lithosphere is broken into a clumsy jigsaw puzzle of rock.

Just off its east coast, deep beneath the seafloor, giant chunks of Earth’s lithosphere and crust are being sucked beneath the country in a process called subduction. Rock from the subducting plates turns to magma when it reaches the mantle, creating hot spots that, over millennia, melt through the crust and break through as lava, forming volcanoes.

Japan is an archipelago, a cluster of islands that sit on a particularly active spot in the tectonic neighborhood, where a thin finger of the North American Plate extends down between the Eurasian and Pacific Plates.

The largest of the islands, Honshu, is in an especially precarious position, straddling the boundary between the Eurasian and North American Plates.

On the other side of the world, beneath the Atlantic Ocean, the tectonic plates are moving apart, or diverging, which creates a more stable seismic environment.

Scientists rate the strength of an earthquake using the moment magnitude scale, a system that gauges the amount of energy released by the quake and assigns it a number.

Determining the magnitude of an earthquake is a tricky business. After the fact, seismologists study measurements of the ground’s movement taken by seismographs and evaluate the damage done by the quake to decide what magnitude to assign to the event.

Sendai, a large city close to the epicenter, was hit by the full force of the quake, but all of Honshu felt it.

When that combined motion is in the ground beneath your feet, the effects can be devastating.

It began not with a jolt, like many quakes, but with an almost lazy undulating rocking motion that slowly built in intensity until the station’s roof rattled violently and glass shattered on the platform.

Sandy soil can store a lot of water. The grains of sand are stacked haphazardly, with water molecules between them.

The four main types of seismic waves each have distinct characteristics. Primary waves and secondary waves are body waves—they travel through the layers of the Earth beneath the crust. Primary waves are the only kind that can travel through both solid rock and molten lava.

When the shaking subsided, about 26,600 houses had been destroyed, and 1,476 people were dead.

Bookshelves and dressers had capsized, scattering their contents everywhere.

Another Otsuchi resident, Yukari Kurosawa, was told a simpler adage when she was young: “If a big earthquake hits and the ocean draws back, run!”

Minutes after the first warning, the tsunami swept past a GPS buoy, which measured its height.

In the town of Ishinomaki, dead center along the coast of Miyagi, residents were lulled into a false sense of security by the early tsunami predictions.

In the town of Kesennuma, the water first appeared innocuous enough, traveling far inland along the Okawa River. In advance of the tsunami, much of the water retreated.

In minutes it had breached the walls and moved into the town with deadly speed.

As the flood sluiced inland, the current was fast and strong enough to drown even the most accomplished swimmer.

That speed, coupled with the possibility of being crushed by massive amounts of debris—including entire houses—made the flood virtually impossible to escape.

He was relieved when the second wave ebbed.

At sundown, it began to snow in earnest.

A sprawling collection of reactors and support buildings, the Fukushima Daiichi plant covered almost 1.5 square miles along the coast of the Pacific Ocean.

At the Daiichi plant, the reactors were housed in six square buildings that had been painted a cheerful baby blue. A splattering of white on one corner of each building mimicked the dappling of sun on the water.

But while other power plants burn oil, gas, or coal to generate the heat that starts the process, nuclear power plants use uranium. And rather than burn it to release energy, they use nuclear fission, a process that unlocks the energy stored inside a tiny, tiny package: the nucleus of an atom.

When neutrons fly away from one fuel rod, the surrounding water slows them to the optimal speed before they reach the next uranium nuclei, making them more likely to create fission.

Water is the workhorse of a boiling water reactor, performing three vital functions: It slows down the freed neutrons so the chain reaction is more likely to occur, but it also drives the turbines and cools the reactor.

Each reactor had two diesel generators, as well as batteries, that could power it in an emergency.

Triggered by emergency systems, control rods automatically shot up into the reactor cores, putting a damper on the movement of neutrons between the fuel rods.

But when the second wave barreled in ten minutes later, it was closer to 50 feet tall—about as high as a five-story building. It easily rolled over the plant’s 30-foot seawall, sweeping a tractor trailer into the building complex and pulling a massive oil tank into the ocean when it receded.

“Just as I thought I was going to die with water encroaching from below,” he later remembered, “a senior employee in the same situation broke the glass of the gate and escaped, and then helped me out by breaking the glass on my side. When I did escape from the confinement, water had inundated to the height of immediately below my jaw. I was really scared.”

A car is tossed like a tub toy by a wave that inundated the North side of the Fukushima Daiichi plant.

Most reactors were built long before fast, compact computers were available, and Fukushima Daiichi, which was commissioned in the 1970s, was no exception. They are complicated contraptions with hundreds of parts, every one of which feeds back through wires to the control room.

A team of nuclear engineers and high-level Tokyo Electric Power Company (TEPCO) staff had gathered around a horseshoe of tables laden with computers in the emergency response center.

Operators managed to get a reading off a water-level indicator inside the reactor in unit 1.

By about 9:00 P.M., the water in unit 1 had boiled down to below the tops of the reactor’s fuel rods, and they were most likely already melting. But no one knew the situation was that dire.