Chapter 6 Earthquakes

stress -a force that acts on a rock to change its shape or volume

- “pushing” and “pulling” of rocks

Rock deforms in 3 ways:-compression-tension-shearing

Forces in the Earth’s Crust

fault -a break or crack along which rocks move*location of earthquake movement

Two areas of most faults:hanging wall

-block of rock above the fault line

foot wall -block of rock below the fault line

Kinds of Faults

compression squeezes the rocks of the crustuntil it folds or breaks-the rock becomes more dense-convergent boundary

Forces in the Earth’s Crust

Kinds of Faultsreverse fault -a fault in which the hanging wall moves

up the footwall *caused by compression*

Footwall

Hanging wall

Hanging wall

Foot wall

tension -pulls on the rocks of the crust, causing rocks to stretch out over a large area-rock becomes less dense

-divergent boundary

Forces in the Earth’s Crust

Kinds of Faults

normal fault – a fault in which the hanging wall moves

down along the fault line above the footwall

*caused bytension*

Hanging wall

Foot wall

shearing -pushes rock of the crust intwo different directions-density does not change-transform boundary

Forces in the Earth’s Crust

Kinds of Faultsstrike slip fault

-a fault in which the blocks of rock move past each other sideways. There is very little “up” and “down” motion. (thrust fault)*caused by shearing*

Name: Date:Class: 6.1 Pop Quiz

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Changing Earth’s SurfaceScientists use the terms anticline and

syncline todescribe upward and downward folds in

rock.

anticline – a fold in rock that bends upwardsyncline – a fold in rock that bends

downward

Changing Earth’s Surface

plateau – a large area of flat land raised high above sea level

-formed when forces in the Earth’s crust push up large, flat blocks of rock