Scienceville
Earthquake
People have studied earthquakes for nearly 2,000 years, even the Moon has quakes, and clever buildings can sway safely. Let's learn how we understand and prepare for shaking ground.
Did you know?
In 132 CE, Zhang Heng of China built a bronze earthquake detector with eight dragons around the top. When the ground shook, one dragon dropped a ball into the mouth of a bronze toad below!
The Moon has quakes too! Apollo astronauts left instruments called seismometers on the Moon between 1969 and 1972. They found that moonquakes can keep shaking for up to an hour, because little on the Moon dampens the shaking.
Old wooden pagodas (tall tower-like temples) in Japan have a central pillar called a shinbashira. Tokyo Skytree copies this idea: a 375-metre concrete column inside the tower helps cancel out swaying during earthquakes.
Try this: Practise Drop, Cover, Hold On
Practise this calmly with your family. Drop: get down on your hands and knees. Cover: crawl under a sturdy table and protect your head and neck with one arm. Hold On: grip the table leg and stay there until the shaking stops. No table nearby? Kneel beside an inside wall and cover your head and neck. Find a safe spot in every room.
Go further: Measuring a Quake's Power
Today, scientists usually describe big earthquakes with the moment magnitude scale. Like the Richter scale, it uses numbers, but each step is huge: going up by one whole number means about 32 times more energy! So a magnitude 6 earthquake releases about 32 times the energy of a magnitude 5. Seismometers around the world record earthquakes every day, and most are tiny, far too small for anyone to feel.