Now, hold the same SlinkyTM off the floor between two people. Predict what will happen when the coils are released. Geologists describe earthquakes as the fracturing of rock on the outer layer or surface of the earth caused by accumulated strain during geological processes. This process is the moving of plates on the Earth's surface that pull apart, collide, slide under or slide against each other. P-waves arrive first after an earthquake and travel through solids, liquids and gases.
Shear means moving back and forth like scissors or shears.
S-waves are the second to arrive after an earthquake. S-waves can't travel through liquid.