It
was a Tuesday aſt ernoon. T e day
was calm in Haiti. Suddenly, the ground shook. Roads buckled. Shacks collapsed. Schools crumpled. Stores tumbled. Whole neighborhoods were flattened. T e ground shook for more than 35 seconds,
then stopped. T e sky turned gray with dust. Fires burned. People called for help. In that brief moment, over a million people lost their homes, and at least 200,000 were killed. Stunned, many people stood in the streets,
which were filled with debris. T ey didn’t really know what had happened or how it would change their lives. A violent earthquake had shaken Haiti, and
it wasn’t over yet. Less powerful quakes, called aſt ershocks, followed. T ey leveled the few buildings still standing. An earthquake is a sudden and oſt en violent
shaking of the ground. Most earthquakes happen along the edges of the giant plates that make up Earth’s crust. T e places where plates meet are called faults.
How Plates Move Earth’s plates move slowly, from 2 cm to 15 cm per year. As they move, they pull apart, grind past one another, or crash together. In Haiti, two grind against each other. Sometimes the plates stick. T is causes
pressure to build up. When the pressure becomes too high, the plates slip with a sudden jolt. T at jolt creates ripples, or seismic waves, that move through Earth. Most earthquakes are too small to feel.
About 100 each year are big enough to cause real damage. Scientists are working to learn more about these quakes. T ey want to save lives and protect buildings. Scientists use seismographs to help detect
quakes. T ese instruments pick up and measure seismic waves. Some waves are short, but fast. T ey don’t cause much damage. Others are bigger, but slower. T ese waves can cause a lot of damage. Using several seismographs, scientists can
pinpoint exactly where on Earth’s surface an earthquake happened. It’s called the epicenter.
A crack in the road marks an area near the epicenter of the earthquake in Haiti.
12 NATIONAL GEOGRAPHIC EXPLORER
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