FAULTS • Click here • Three types • Stresses
I. Seismic Waves Today • Invisible vibrations called waves ( like ripples in a pond) • Race out from Focus (origin) in all directions. • Carry tremendous Energy to Earth’s interior and surface. • Rock type and Soil affect amount of damage done by earthquake.
II. Types of waves • A. Primary Waves (P-waves) • Compress and expand earth like an accordion. • Cause buildings to Contract and Expand. • Move through Liquids and Solids
Types of Waves Continued • B. Secondary Waves (S-waves) • Vibrate from side to side and Up and Down. • Shake the ground back and forth. • Shake structures violently at the surface. • Travel only through Solids
Types of Waves Continued • C. Surface Waves • Combination of S and P Waves. • Produce most severe ground movement. • Rolling or shaking movements.
How does it work? • Earthquakes • http://www.windows2universe.org/earth/interior/plate_tectonics.html • Faults • http://www.windows2universe.org/earth/geology/fault.html
Measuring Earthquake • A. Seismograph • Records ground movements
Measuring Earthquake Cont’d • B. Mercalli Scale • Describe how earthquake affect People, Buildings, and Land Surfaces. • Same earthquake can have different ratings depending on location.
Measuring Earthquakes Cont’d • C. Richter Scale • Measures the size of the seismic waves. • Good for small local earthquakes.
Measuring Earthquakes Cont’d • D. Moment Magnitude Scale • Used today • Measures total energy released by Earthquake. • Good for local or Far away Quakes. • Use various data to get rating ( strength of rock, earth movement, size of waves)
Pictures of Earthquakes This is not good!