Primary waves:

Primary waves are also called p waves. The primary waves compress and expand the ground like an accordion.

Secondary waves:

Secondary waves are called s waves. They come after the primary waves. The s waves are not as big as the p waves. They come and shake structures violently.

Surface waves:

Sometimes surface waves are formed by p wave and s waves, although they move much slower than p and s waves.

Types of stress

Shearing:

Shearing is a stress that pushes a mass of rock to slip and/or break apart or change shape.

Tension:

Tension is stress that stretches the rock like bubble gum.

Compression:

compression is stress that squeezes a rock until it folds and breaks. When one plate pushing the other can compress a rock like a gaint trash compactor.

Deformation:

Deformation can change any shape of volume of the earth's crust. If you speed up time billion years or so, you could see the deformation of tilt, slid and fold.

Kinds of Faults

Strike slip faults:

Shearing creates strike slip faults on either side of the fault, slips past each other sideways with little up or down a strike slip fault that forms boundry between two plates.

Normal faults:

In a normal fault the fault is at an angle, so one block of rock lies below and one above the fault. The one above is called hanging wall. The one below is called a footwall.

A reverse fault:

A reverse fault has the same structure as a normal fault, but the blocks move in the opposite direction. One side of the fault is at an angle above the other. The rock forming the hanging wall of a reverse fault slides up and over the footwall.

Mountain formation:

Fault movement can change a flat plain to a towering mountain range. A fault- block mountain forms when normal faults uplift a block of rock. When a block of rock is left between two faults because the faults form a parallel if the hanging wall of each fault slips downward and one block slips upward. When 2 plates collide together it can cause compression and folding of the crust.

Monitoring risk in us:

Geologists can't predict when and where earthquakes happened. But Geologists can predict earthquakes have occurred. Earthquakes are rare on and near the rockies North America is under much stress. EARTHQUAKES

Seismic waves:

Seismic waves travel in the air carrying the energy [sound] and release it during an earthquake. Seismic have the power of an earthquake. The seismic wave carries it away from the focus across the surface and through the earth's interior.