Post on 19-Jan-2016
Earthquakes
A whole lot of shake’n going on!
Earthquake terms:
• EARTHQUAKE-Vibration of the Earth caused by the rapid release of energy in the crust.
• Motion takes place along a FAULT.• Energy radiates out from the FOCUS.• Energy moving outward from the focus travels
in the form of SEISMIC WAVES.• The EPICENTER is the point above the focus on
the surface of the Earth.
What causes the rock to break?
• STRESS- Forces that push and pull on the Earth’s crust.
• Three types of stress:– Compression – Tension– Shear
As rocks undergo stress they can:
–Change shape–Change volume–Move up–Move down–Move sideways– Fracture or breakThis is called
deformation
Types of faults:
• Normal– Stress-tension
• Reverse– Stress-compression
• Strike slip– Stress-shear
http://www.iris.edu/gifs/animations/faults.htm
• http://video.nationalgeographic.com/video/player/environment/environment-natural-disasters/earthquakes/earthquake-montage.html
Types of Seismic Waves
• P-Wave: longitudinal wave. Travels 6 m/s. Passes through solids, liquids, and gases.
• S-Wave: transverse wave. Travels 3.5 m/s. Passes through solids.
• Surface Wave: Travels along the surface. Most destructive.
• http://www-rohan.sdsu.edu/~rmellors/lab8/l8maineq.htm#swave
Putting it all together
How a seismograph works
• http://www.wwnorton.com/college/geo/egeo/flash/8_3.swf
Reading P and S waves