Geology Stress and Strain

Force exerted per unit area on a rock.

The physical change in a rock caused by stress.

Permanent change in rock shape after stress surpasses yield point; the rock does not return to its original shape.

Rock fracturing under stress; the rock breaks.

Reversible change in rock shape after stress is removed.

Pressure exerted by fluids in the open spaces (pores) of rock or sediment.

How quickly a material deforms under stress.

Special geologic symbol representing the orientation of inclined rock layers.

Arch-like fold with beds dipping away from center.

2D representation of geologic formations and structures at the Earth's surface.

Bent layers of sedimentary rock, often creating ridges; not related to ocean reefs.

Faults that don't reach the Earth's surface, often associated with monoclines and domes.

Faults where the hanging wall moves down relative to the footwall due to tensional forces, common at divergent plate boundaries.

Faults where the hanging wall moves up relative to the footwall due to compressional forces.Thrust faults are a special type.

Symmetrical or semi-symmetrical upwarped rock layers shaped like an inverted bowl. Often formed by compressional forces or igneous intrusions.

Fault movement where blocks slide horizontally past each other, either left (sinistral) or right (dextral) relative to an observer.

The point within the Earth where an earthquake's rupture begins.

The theory that earthquakes occur when built-up stress in rocks overcomes friction, causing them to rupture and spring back to their original shape.

Energy waves traveling through the Earth generated by an earthquake.

The point on the Earth's surface directly above the earthquake's focus.