TED-Ed: Why do buildings fall in earthquakes? - Vicki V. May

The video explores the impact of earthquakes on buildings, debunking common myths about building collapse. It explains how buildings respond to seismic activity, focusing on factors like mass and stiffness. The 1985 Mexico City earthquake serves as a case study to illustrate the concept of resonance, where seismic waves matched the natural frequency of mid-sized buildings, causing them to collapse. Modern engineering solutions, such as base isolation and tuned mass dampers, are discussed as methods to prevent such collapses by absorbing shocks and reducing vibrations.

What primarily causes buildings to collapse during an earthquake?

• Location on a fault line

• Splitting of the ground beneath

• Displacement of the foundation and resulting vibrations

• Direct shaking of the ground

What was a significant factor in the collapse of mid-sized buildings during the 1985 Mexico City earthquake?

• The buildings were too tall

• The buildings were too short

• Resonance with the earthquake's frequency

• Poor construction materials

How does increasing a building's mass affect its natural frequency?

• It has no effect on the natural frequency

• It decreases the natural frequency

• It increases the natural frequency

• It makes the building more flexible

What is the purpose of base isolation in building design?

• To make the building stiffer

• To isolate the foundation's displacement from the rest of the building

• To increase the building's height

• To reduce the building's mass

Which system is used to cancel out resonance by oscillating out of phase with the natural frequency?

• Base isolation

• Flexible columns

• Seismic retrofitting

• Tuned mass damper