Meltdown: Earthquake, Tsunami, and Nuclear Disaster in Fukushima

by Deirdre Langeland

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  For my mother, Ricky Langeland, who taught me how to be curious, do my research, and think like a scientist.

  Most of the area of Japan is made up of four major islands. The largest of these, Honshu, is divided into five distinct regions. The northernmost, the area most affected by the March 11, 2011, earthquake, is known as Tohoku (shown here in dark blue).

  PREFACE

  Fukushima. To people all around the world, the name has come to mean one thing: nuclear disaster. They remember several long weeks in March 2011 when they turned on the news every day and saw thick smoke billowing from nuclear reactors, carrying potentially deadly radiation into the environment.

  In reality, Fukushima is a prefecture in Japan—a government district similar to a state in America. It’s the southernmost prefecture in the Tohoku region, an area of about 25,000 square miles that is famous for its remote beauty. Dense forests and volcanic peaks define the landscape. Fog drifting in from the northern Pacific Ocean blankets its rice paddies, apple orchards, and cattle farms. Before the disaster, Fukushima was known as a lush farming area that supplied produce, dairy products, and seafood to the rest of Japan. But in the space of a few days, all of that changed.

  Roughly midway along the Fukushima coast, six nuclear reactors were lined up in a neat row along the shore. Owned by the Tokyo Electric Power Company, or TEPCO, they were part of the Fukushima Daiichi power plant. (Dai-ichi means “one” in Japanese. A second power plant, called Fukushima Daini, meaning “two,” was located about 6 miles down the shore.)

  On March 11, 2011, the plants were hit by a one-two punch: First, there was the earthquake, the strongest ever measured in Japan. Then came the tsunami, an inescapable wall of water that killed tens of thousands. Together, they crippled the reactors at Fukushima Daiichi, setting off a chain of events that threatened the safety of millions.

  * * *

  Like most disasters, the Great Tohoku Earthquake and tsunami came with little warning. There had been foreshocks, smaller earthquakes that shook the countryside for days before the main event, but there’s nothing unusual about earthquakes in Japan. On average, Japan experiences about two thousand earthquakes that are strong enough to be felt every year. In real time, it’s impossible to know whether an earthquake is its own event or a precursor of something bigger on the way. Only afterward, once the Big One has come and gone, can seismologists go back and see the pattern that led up to it. And so, the millions of residents of Tohoku went about their business that afternoon in March as they had on all of the others before.

  That was certainly true for Ryoichi Usuzawa, a sixty-two-year-old grandfather with salt-and-pepper hair who was working from his home in the town of Otsuchi. He was pleased with himself because he had just finished writing a report and was binding it into a folder and adding tabs. His wife was downstairs with the family dog, a Shiba Inu named Taro. It seemed like a pretty ordinary Friday afternoon, and Ryoichi was happy to be wrapping up the week’s work.

  But what happened next was anything but ordinary. “Suddenly, there was a[n] … enormous earthquake,” he later told a journalist. “Nothing like what we’d experienced in the past—a truly terrifying quake. It made me wonder if our house would collapse; if I might die. The printer, computer, bookshelf, records—everything came tumbling down. I couldn’t move a step.”

  When the shaking stopped, just a little past 2:50 P.M., Ryoichi did what he had probably done after the hundreds of smaller earthquakes that had shaken his house in the past: He began to clean up the mess. Even when his wife told him there was a tsunami warning, he didn’t think it was a serious threat. After all, his family had lived there for decades and the water had never reached their land. For the next half hour, he straightened up and tried to fix the television as his sons, his daughter-in-law, and a grandchild gathered outside the house. He tried to calm his nerves, which had been jangled by the unusually strong earthquake.

  Then he heard his wife shouting: “Oto-San, run from the tsunami!”

  * * *

  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 Ryoichi had no way of knowing that. He only knew that his wife’s last words as she ran for safety were “Look after Taro!” So he headed up the stairs, in the direction he had last seen the dog going.

  Moments later, muddy water surged up the stairs after him.

  DAY 1

  earthquake

  Friday, March 11, 2011, 2:46 P.M.

  Reactor Status

  Reactor 1: Fully operational

  Reactor 2: Fully operational

  Reactor 3: Fully operational

  Reactor 4: Shut down for inspection

  Reactor 5: Shut down for inspection

  Reactor 6: Shut down for inspection

  Standing on Earth, it’s difficult to appreciate its movement. The entire planet spins on its axis at more than 1,000 miles per hour (mph) and hurtles along its orbit through space at 66,660 mph. It’s no wonder, then, that those of us sitting on its surface hardly notice the slow creep of its tectonic plates. But miles beneath the soil and sand, the mountains and oceans, Earth’s lithosphere is broken into a clumsy jigsaw puzzle of rock. The puzzle pieces, called tectonic plates, sit on the asthenosphere, a layer of Earth that shifts and flows.

  Rocks in the asthenosphere are under so much pressure that they move in and out of solid form—sometimes they are solid rocks, sometimes liquid magma. Resting on top of this constantly changing layer, the plates creep over, under, and past each other at a rate so slow it would make a snail blush.

  More than anything else, Japan has been shaped by the push and pull of plate tectonics. 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. That upwelling magma is responsible for the breathtaking mountainous landscape of Japan, and those subducting plates cause most of the earthquakes that shake the country.

  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. To the east of the island, the North American and Pacific Plates meet in a section of the seafloor called the Japan Trench. There, the Pacific Plate slides beneath the
North American Plate in what’s known as a subduction fault.

  Mount Fuji, Japan’s tallest peak, is one of more than a hundred active volcanoes in the country.

  The tectonic plates surrounding the Pacific Ocean are converging, or moving toward each other, resulting in a rough arc of subduction faults around the edge of the ocean. Because these faults produce volcanic activity, the arc has become known as the Ring of Fire. 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.

  It sounds harmless enough, and even more so when you realize that the Pacific Plate creeps westward at only about three and a half inches per year. But tectonic plates don’t slide smoothly—they stick. And on a scale as large as a tectonic plate, a little bit of motion combined with a lot of stickiness can build up an enormous amount of energy.

  As the Pacific Plate slides beneath the North American Plate, it catches the North American Plate’s edge. Over time, the movement of the Pacific Plate pulls the North American Plate downward, like the bucket of a catapult that is being readied to fire. The upper plate begins to bend, curving at the fault and forming a deep ocean trench. Tension builds between the two. Potential energy grows. When the potential energy in the fault becomes greater than the force, called friction, that holds the plates together, the top plate breaks free and springs upward. The subducting plate surges forward. The catapult has been released. The strength of the resulting earthquake depends on how much energy has built up in the fault before it budges, how much of the fault slips, and how far it moves.

  Japan’s landscape has been shaped over millennia by the subduction fault off its eastern coast. Rock from the subducting plate melts when it reaches the mantle, creating hot spots of magma.

  The many faults surrounding Japan are constantly slipping. In fact, the country experiences a tremor somewhere within its borders every five minutes or so. Most of those are too small for humans to feel. Of the two thousand or so each year that are strong enough to be felt, most are small tremors, which do little more than rattle dishes and set off car alarms. But the Great Tohoku Earthquake, as it came to be known, was far more powerful than any that had been measured in Japan before.

  * * *

  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. Each number on the scale is ten times more powerful than the one before it. An earthquake that rates a 5 on the scale is strong enough to be felt by everyone, rattling dishes and waking sleepers in their beds. An earthquake that rates a 6 is ten times more powerful than a 5. A 7 is 100 times more powerful than a 5, toppling furniture and shaking loose plaster and bricks in older buildings. The Tohoku quake was measured at 9.1.

  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.

  Before 2011, most scientists believed that the Japan Trench could not produce an earthquake stronger than magnitude 7.5. That’s because it’s not a very sticky fault—it moves forward pretty smoothly, without building up too much friction between the plates. And less sticking means that less potential energy builds up in the fault.

  But in the end, it was the fault’s slipperiness that proved the scientific predictions wrong. The upper plate lurched forward on March 9, causing a magnitude 7.2 earthquake—on its own a major event. Three more large quakes, each larger than magnitude 6, followed that same day. Then the fault ruptured again.

  * * *

  At 2:46 P.M. on March 11, an area of the North American Plate about 190 miles long broke free from the Pacific Plate. The fault was packed with slippery clay, which acted like the water on a slip-and-slide, allowing the Pacific Plate to leap more than 160 feet westward—farther than anyone had thought it could go. Energy surged from the rupture like a bomb blast, racing toward the shore at nearly 4 miles per second.

  In Japan, March marks the end of the school year. On that Friday afternoon, many kids were nearing the end of their last day of classes. Office workers were grinding through afternoon meetings and paperwork. Stores were preparing for the afternoon rush. Then the earthquake sirens sounded. Seconds later, the ground began to shake. Glass shattered, roadways crumbled, and telephone poles toppled.

  Three prefectures along the northeastern coast of the island—Iwate, Miyagi, and Fukushima—were closest to the fault and took the hardest hit. In the town of Otsuchi, in Iwate prefecture, Ryoichi Usuzawa was rattled at his desk. Nearby, a barber named Seizo Sasaki was in his shop when the quake hit. “First, everything started to sway, slowly and lazily,” he later recalled. “Then with a sudden wrench, the quake hit hard.”

  At first, it seemed like every other earthquake. All over the island of Honshu, people followed emergency guidelines and dropped to the floor, sheltering under desks and tables as they waited for the shaking to stop. Normally, an earthquake lasts for a few seconds, maybe as many as thirty. A big earthquake might go on for a full minute—but not this time. A minute ticked by, and the shaking didn’t stop. It got worse. In some places, it lasted for five long minutes.

  All over Japan, people began to realize that this was not an average event. “I never experienced such a strong earthquake in my life,” a city official from Sendai told a reporter in disbelief that night. “I thought it would stop, but it just kept shaking and shaking, and getting stronger.”

  Up and down the coast, violent tremors knocked out power and toppled warning towers. Sendai, a large city close to the epicenter, was hit by the full force of the quake, but all of Honshu felt it.

  * * *

  The energy that surges from a ruptured fault shakes the earth from crust to core. The movement produces what is known as seismic waves. Most of the shaking that we think of as an earthquake is caused by a category of seismic wave known as surface waves, which roil Earth’s crust, taking everything on it for a ride. Of those surface waves, Love waves shake from side to side, while Rayleigh waves roll in circles, creating up-and-down motion at the surface. If you’ve ever been on a boat as it rocked over ocean swells, you probably have a good idea of what Rayleigh motion feels like. Imagine being vigorously shaken from side to side as the boat is riding over those swells, and you can start to get an idea of what it feels like when Rayleigh and Love waves combine in an earthquake. When that combined motion is in the ground beneath your feet, the effects can be devastating.

  In Tokyo, about 180 miles from the epicenter, journalist David McNeill was in a subway station when the earthquake struck. He later described the rolling motion of the surface waves: “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 … We stood frozen to the spot, hearts thumping violently, and watching the roof, silently praying it wouldn’t fall on top of our heads.”

  Buildings in the city, designed to withstand earthquakes, bent rather than broke as the ground beneath them rolled. “What was scariest was to look up at the skyscrapers all around,” one witness said. “They were swaying like trees in the breeze.”

  But the subway did not collapse, and the skyscrapers didn’t crumble. Even in the midst of such a massive quake, many of Japan’s earthquake protection systems worked.

  * * *

  Japan is often called the most earthquake-prepared country in the world. Since an earthquake killed thousands in the city of Kobe in 1995, the nation had spent sixteen years reinforcing bridges, reconstructing old buildings with earthquake-resistant technology, and creating earthquake warning systems. New buildings in Japan are designed to rock and flex rather than break, helping them weather strong quakes. But in 2011, it may have been the warning systems that saved the most lives.

  Custome
rs huddle against a support pole for protection as the ceiling in a bookstore collapses during the Great Tohoku Earthquake.

  When a fault ruptures, the energy travels in four kinds of seismic waves. While Love and Rayleigh waves roil Earth’s surface and secondary waves shake solid rock deep within the planet, primary waves travel through Earth’s mantle and core, causing little damage on the surface. Each kind of wave moves at a different speed, and those different speeds make it possible for some very clever equipment to detect an earthquake before it can be felt by humans.

  Primary waves, or P waves, travel very fast—as fast as 3.7 miles per second through Earth’s crust and 8 miles per second through the core. When earthquake monitoring stations register P waves, they trip early warning sirens, giving people crucial time to turn off motors, stop surgeries, and pull cars to the side of the road before the surface waves arrive. The warnings trigger automated safety systems, forcing elevators to come to a halt and open their doors. Subway trains slow to a stop. For towns and cities close to the epicenter of the Great Tohoku Earthquake, the warning came fifteen seconds before the tremors. That might not sound like a long time, but it was enough to keep cars and trains from crashing, prevent people from being trapped in elevators, and give others time to scramble to cover.

  The early warning system worked perfectly in Fukushima prefecture. When the first seismic waves reached the power plant at Fukushima Daiichi, fail-safe systems shut down the reactors. When the prolonged shaking knocked out power lines, backup generators clicked on to run the plant’s instrument panels and keep critical coolant moving through the reactors.