# How Skyscrapers Survive Earthquakes A cutaway Tokyo\-style tower on a shaking diorama: dial up a quake and watch its braced frame, oil dampers, giant pendulum and rubber bearings keep it standing By Ham Sandwich Topic: Engineering [Open the interactive Jig](https://ask.jig.com/j/0PnB2Rj8vof0) ## Guide ### 1. How Skyscrapers Survive Earthquakes Tokyo sits where several plates of the Earth's crust meet, so the ground there shakes often\. Yet its tall towers stay standing\. This model tower is cut open so you can see the clever machinery inside\. Drag empty space to turn it\. Scroll or pinch to zoom in on any part\. ### 2. Feel the ground move An earthquake shoves the ground sideways, back and forth\. The bottom of the tower moves at once, but the top wants to stay where it was, so the tower bends and sways\. Press the button to shake this tower with nothing extra to help it\. That lag is inertia: heavy things resist being moved\. ### 3. A strong, bendy skeleton Inside is a steel skeleton\. Columns carry the weight, X\-shaped braces stop the frame folding sideways, and a concrete core rises up the middle\. Deep trusses called outriggers tie the core to the outer columns, so the whole tower bends together like one stiff tree trunk\. Towers are meant to flex a little\. Bending without snapping is what keeps them safe\. ### 4. Shock absorbers in the walls Oil dampers sit inside these V\-shaped braces\. When the floors slide past each other, a piston pushes oil through tiny holes, turning the shaking into a little heat\. Switch them on and the sway dies away much sooner\. They work like the shock absorbers on a car or a bike\. ### 5. The giant pendulum Near the top hangs a huge steel ball on cables: a tuned mass damper\. It is tuned to swing at the same rhythm as the tower, but always a moment behind, so it pulls the other way and calms the sway\. Give the tower a push and watch them dance\. Taipei 101 in Taiwan has a famous one: a 660 tonne ball, 5\.5 metres wide, made of 41 steel plates\. ### 6. Floating on rubber Under the building sit stacks of rubber and thin steel plates called base isolators\. They are stiff up and down but soft sideways, so the ground can slide beneath while the building rocks slowly above\. A gap around the base, called a moat, gives it room to move\. The steel plates stop the rubber bulging under the weight, while it still bends sideways\. ### 7. Try the magnitude dial Earthquake size is measured by magnitude, the scale people often call Richter\. Each step up means about ten times bigger shaking waves and about 32 times more energy\. Drag the needle on the seismograph dial, or pick a size here, and the quake begins\. The model shrinks the biggest shakes so they fit on screen\. Japan also reports local shaking on a separate scale called shindo\. ### 8. All together now Real towers mix these ideas: a strong frame, dampers to soak up energy, and sometimes a pendulum or rubber bearings\. Compare the same big quake on a bare tower and on one with every helper switched on\. Watch how far the top travels\. Tokyo Skytree borrows an idea from old wooden pagodas: a concrete column in its centre that sways at a different rhythm from the outer tower\.