Meltdown!: The Nuclear Disaster in Japan and Our Energy Future
Chapter 1 EARTHQUAKE TSUNAMI MELTDOWN Although it strikes suddenly the Great Tohoku Earth quake has been building up for hundreds of years Like all quakes it happens because Earth s outer rocky layer called the crust is made up of many large slow moving pieces These are called plates The crust lies above another rocky layer called the mantle The mantle is so hot that it is not completely solid It flows in giant loops from Earth s core to the crust The pattern is the same one you can see in a pot of boiling water on a stove But the movement is much slower because the mantle is made of rock At the top of the mantle different loops flow in different directions The flowing mantle drags the crust with it That explains the cracking and movement of the plates Most of the Pacific Ocean lies above the Pacific Plate Japan sits just west of the Pacific Plate on three other plates Those are the North American Plate to the north the Eurasian Plate to the west and the Philippine Plate to the south EARTHQUAKE Year after year the Pacific Plate moves about 8 to 9 centimeters 3 to 3 5 inches closer to Japan That s about half as fast as your hair grows It plows
under the North American Plate and the Philippine Plate of the east coast of Honshu Japan s main island The rocks of the Pacific Plate lock with the rocks at the edges of the plates above it That bends the upper plates downward With every centimeter that the Pacific Plate moves the upper plates bend more With every centimeter the force on the locked rocks grows Finally that force becomes more than the locked rocks can handle The rocks start to crack crumble and split apart That increases the force on other nearby rocks even more Those rocks also break apart All along the line joining the plates the cracking quickly spreads That releases the bending force and the edge of the top plate springs upward 5 to 8 meters 16 to 25 feet That is how the Great Tohoku Earthquake begins Its underground starting point called the focus or hypocenter is about 32 km 20 mi beneath the epicenter on the ocean surface For 220 seconds or nearly four minutes the cracking spreads rapidly in two zones The cracks reach a total of 300 km 185 mi in length before they stop Some sections of rock have shifted by as much as 60 m 200 ft Part of the island of Honshu is now 2 4 m 8 ft closer to North America The quake is so powerful that it even shifts Earth s tilt The North Pole and the South Pole are 10 to 25 cm 4 to 10 in from where they were before EARTHQUAKE TSUNAMI
TSUNAMI The sudden upward movement of the top plate creates a huge tsunami A bulge of water about 180 km 110 mi wide begins traveling toward the Tohoku coast In the deep ocean a tsunami can travel at the speed of a jet plane It travels slower in shallower regions As the tsunami reaches shallow water near the Tohoku shore it slows and water piles up even higher The giant wave begins surging onto the closest land about 72 km 45 mi west of the epicenter about 10 to 20 minutes after the quake An hour later it reaches the major city of Sendai where it begins flooding the airport Most Japanese coastal towns have walls to keep them safe from tsunamis But this one is higher than the walls can handle At some narrow inlets it reaches as high as 39 m 128 ft It roars ashore It uproots trees knocks buildings off their foundations and carries cars and trucks in rivers of trash In some locations it rolls inland as far as 10 km 6 mi Loss of life and property is astonishing The tsunami damages or destroys roads railways a dam and more than 125 000 buildings Property damage may be more than 300 billion More than 5 300 people are injured and more than 23 300 are dead or missing Most of the damage and casualties are the result of the tsunami
PREPARATION SAVES LIVES The Tohoku quake is extremely powerful registering 9 0 on the Richter scale the most common measurement of earthquake intensity Only four earthquakes since 1900 have released more energy Yet the loss of life in Japan though large was much less than in serious quakes in other parts of the world For example the 7 0 earthquake that struck Haiti in 2010 released only a thousandth as much energy and did not cause a tsunami Yet it was more than ten times as deadly More than three hundred thousand people died In 2005 a 9 1 earthquake under the Indian Ocean near Aceh on the northern tip of Sumatra Indonesia triggered a tsunami similar to the one that struck Tohoku The Aceh tsunami was also ten times as deadly as Tohoku It killed more than 230 000 people on Sumatra on other Indonesian islands and in neighboring countries EARTHQUAKE TSUNAMI
