This animation shows the differences between the three types of faults and illustrates how they are formed. View 1 shows a normal fault, View 2 shows a reverse fault, and View 3 shows a strike-slip fault.

by Stephen Marshak

>>see: p.211

Seismologists distinguish between different types of seismic waves based on how they move, and whether they travel along the Earth's surface (surface waves) or pass through its interior (body waves). This animation shows two types of body wave motion: View 1 shows shear body waves (also called S-waves) and View 2 shows compressional body waves (P-waves).

by Stephen Marshak

>>see: p.215

Seismologists use two basic configurations of seismographs, one for measuring horizontal ground motion, like the one shown in this animation, and the other for measuring vertical ground motion. Both work on the principle of inertia as described by Newton's law, which states that an object at rest tends to remain at rest unless acted on by an outside force. Thus, during an earthquake, vibrations cause the frame of the seismograph to move. The pendulum apparatus remains fixed as the paper cylinder moves back and forth beneath it.

by Stephen Marshak

>>see: p.218