Science Earthquakes

Stress

Force acting on crustal rock to be deformed

Movement of Earth occurs when stress is greater than strength of rocks

Compression

convergent boundries

shear

transform boundries

tension

divergent boundries

elastic deformation

caused when material is compressed bent or streched

Rock returns to origonal state

Palstic Deformation

Strain that produces permanent defomation

Fault

crack in Earth’s crust along which rock has moved

Elastic rebound

release of strain energy as rock moves along fault

Seismic Waves

vibrations of the ground caused by an earthquake

P waves

squeeze and push rocks in the same direction that the waves are traveling

Fastest wave:travel through liquid and solid

S waves

Moves at right angles to the direction of the wave

Slower than P waves only travel through solids

Surface Waves

Earths slowest wave most distructive

Mercalli Scale

measures intensity

Richter Scale

measures amplitude/magnitude

Seismometer

measues motion of the ground during an earthquake

Seismograph

record produced by a seismometer

Strain

Deformation of material in response to stress