A Monster Quake About a year aſt er the quake in Haiti, an even larger quake struck Japan. Located 129 km east of Japan, the quake happened deep below the Pacific Ocean. T ere, two plates are colliding. During the quake, the fault slipped 30 m. T is quake was a real monster. It measured
a magnitude 9. It was 500 times stronger than the one that struck Haiti. It was one of the five strongest ever recorded. Watch out when a big fault shiſt s under the
ocean. T e quake releases much of its energy into the water. T is creates waves called a tsunami. T ese waves can race across the ocean as fast as a jet plane. In the open ocean, a tsunami might be
barely a bump. But when it hits shallow water, the waves slow, and water piles up. It can plow into land with devastating speed and power. A tsumani may thunder ashore within minutes of an earthquake. T at’s what happened in Japan. T e earthquake there triggered a huge
tsunami. It washed away thousands of buildings, cars, and people. As bad as it was, engineers had worked for years to keep Japan as safe as possible. T ey built stronger buildings and created a warning system.
Safe Skyscrapers Tokyo, Japan’s largest city, was 370 km from the quake’s epicenter. It could have been destroyed, but it wasn’t. Instead of toppling, skyscrapers swayed like trees in the wind. T at’s because engineers used what they
know about earthquakes to design the skyscrapers. T ey built each skyscraper on either shock absorbers or rollers. Instead of tilting when the ground shook, the buildings slid back and forth. T e engineers also used flexible materials
to make the skyscrapers. T ese materials allowed the skyscapers to sway back and forth, instead of breaking. T e engineers added extra supports and braces to each skyscraper, too. Other engineers helped, too. T ey designed
an earthquake alarm system that warned people. About 80 seconds before the quake struck, cell phones, radios, televisions, and computers lit up with a warning. Japan’s seismographs triggered the warning. T ey detected the fastest, but least harmful waves, first. T ey determined from those first waves that the quake was a big one. In the few seconds before the slower, more damaging waves hit, the alarms went off .
The tsunami that struck Japan washed ashore boats and swept cars off the roads.
14 NATIONAL GEOGRAPHIC EXPLORER
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