Ch. 8 Sct. 1

When rocks strain and potential energy builds up over time.

When the potential energy is released because the rock breaks, vibrations are released through the rocks.

The surface of a break in the earth’s rocks/crust

99% of earthquakes occur at a fault Normal Reverse Strike Slip-Fault

Divergent Dip-Slip Fault

ConvergentThrust Fault

•San Andreas pics.•1906 quake.

Waves released by earthquakes Primary Waves (P) Secondary Waves (S) Surface Waves

P wavesTravel fastest through rock Move like compression waves/sound

waves

S wavesTravel second fastest through rockMove like transverse waves/light

waves

Slowest and largest seismic wavesTravel outward from epicenter in a

variety of forms Ocean waves Backward rolling waves Side to side, swaying motion

Most destructive seismic wave

Focus Deep within the earth’s crust where the

actual rock structure snapsEpicenter

The point on the earth’s surface directly above the focus.

Seismograph Records the magnitude of earthquakes

Based on measurements of seismic wave heights from seismograph readings

Difference between 1.0 and 2.0 10x higher waves on seismograph 32x more energy in earthquake

The strongest recorded earthquake in history. 1960 off the coast of Chile 9.5

The strongest recorded earthquake in North America. 1964 near Anchorage, Alaska 9.2

Measure the intensity/damage of an earthquake.

Specific to the distance away from the epicenter.

Occur when earthquakes happen on the ocean floor.

The energy from the quake is transferred to the water and causes huge waves to form.

Waves don’t gain height until they near the land.

See page 216 of text.