Sound

• a longitudinal wave

• Needs a medium of particles to disturb

• Need a source to disturb the particles

• the particles compress and move away

Layers of the Earth

By analyzing how P- and S-waves travel through the Earth, we've been able to conclude several things about the the composition of the inner-earth.

Locating an Earthquake

A station has a seismograph that records the ground movement.

First a P-wave will move the ground.

Then a S-wave will follow.

The time difference (interval) can be translated into a distance which the earthquake occurred.

Locating an Earthquake

is performed when three different seismograph stations can each determine how far the earthquake originated from them.

Earthquake-safe building are more flexible at the posts and base than stiff building.

The purpose is to avoid pancake collapse after a major earthquake

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Earthquake Safe Building Design

​Pancake Collapse