Seismic Waves
What do we know?
• Energy that travels through the earth
caused by the sudden breaking of rock within
the earth or an explosion
•Examples?
Types of Waves
• P-waves
– The fastest kind of seismic wave
– The P wave can move through solid rock and
fluids, like water or the liquid layers of the earth.
• S-waves
– An S wave is slower than a P wave and can only
move through solid rock, not through any liquid
medium.
P-waves
It pushes and pulls the rock it moves through
S-waves
S waves move rock particles up and down, or side-to-side-perpendicular to the direction that the wave is traveling in
Earthquakes
• Earthquakes and seismic waves?
• Think for two minutes with your partner about
the relation between earthquakes and seismic
waves.
Earthquakes cont.
• Seismic movement
• Intensity (strength) can fluctuate
• Usually last a short time
• Question: Where does the majority of seismic
activity take place?
How do we Measure Earthquakes?
• Intensity
– Based on perceived sensations and effects and
measured by the M.S.K. scale.
• Magnitude
– Measures the amount of energy released by an
earthquake. Measured by the Richter scale.
Richter Scale
Analyze
• Where does the earthquake originate?
• Where does one feel the earthquake?
• Will the epicenter always be directly above the
focus?
Seismic Risks
• The earth’s crust (or land) shifts and moves
causing earthquakes and tsunamis (tidal
waves).
Prevention/Prediction
Seismometer: instruments used to measure
motions in the ground and the seismic waves
generated by earthquakes and volcanic eruptions
Review
Review cont.
• Is this a P or S wave?
Review cont.
• Is this a P or S wave?
Review cont.