In a strike-slip fault, the movement of blocks along a fault is horizontal. The fault motion of a strike-slip fault is caused by shearing forces. Other names: transcurrent fault, lateral fault, tear fault or wrench fault. Examples: San Andreas Fault, California; Anatolian Fault, Turkey.

An asperity is an area on a fault that is stuck or locked. Scientists study areas along long fault zones that have not had earthquakes in a long time in order to determine where the next earthquake may occur. As long faults move, all areas of it will, at some point, become "unstuck" causing an earthquake relative to the the size of the asperity that finally breaks.

View looking into a fault zone with a single asperity. Regional right lateral strain puts stress on the fault zone. A single asperity resists movement of the green line which deforms before finally rupturing.

Left-lateral fault strike slip fault with little or no friction along fault contact. There is no deformation of the rock adjacent to contact. If the block opposite an observer looking across the fault moves to the left, the motion is termed left lateral.

Animation of the single-block "Earthquake Machine", a mechanical model of the earthquake process using a wood block, sandpaper, and rubber bands. This model shows how "Forces, Faults, and Friction" interact as elastic energy is slowly stored when the rubber back stretches and then is rapidly released as the block jerks during an "earthquake".

Graphing time vs. distance using the classic block-and-sandpaper "earthquake machine"

Graphing time vs. strain using the classic block-and-sandpaper "earthquake machine"

Earth is an active place and earthquakes are always happening somewhere. In fact, the National Earthquake Information Center locates about 12,000-14,000 earthquakes each year! This fact sheet illustrates information on the frequency of earthquakes of various magnitudes, along with details on the effects of earthquakes and the equivalent energy release.

NOTE: Out of stock; self-printing only.

This demonstration, squeezing uncooked spaghetti noodles in a wood template set in a vise, effectively shows how asperities (stuck patches) on a fault rupture at different times.

This demonstration shows that rocks are elastic by squeezing a slit core of rock.

Video lecture covers three basic types of tectonic plate boundaries.

Using a block-and-sandpaper model, students collaborate in small groups to investigate how energy is stored elastically in rocks and released suddenly as an earthquake (the earthquake cycle). This activity emphasizes the role of mechanical models in understanding and testing ideas in science.