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Earthquakes

Earthquakes. Stress Faults they cause Seismic Waves Hazards of an Earthquake. Types of Stress. Tension Pulls crust apart Compression Squeezes rock until it folds or breaks Shearing Pushes a mass of rock in two opposite, horizontal direction. Fault.

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Earthquakes

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  1. Earthquakes • Stress • Faults they cause • Seismic Waves • Hazards of an Earthquake

  2. Types of Stress • Tension • Pulls crust apart • Compression • Squeezes rock until it folds or breaks • Shearing • Pushes a mass of rock in two opposite, horizontal direction

  3. Fault a break in Earth’s crust where slabs of crust slip past each other 3 types: normal, reverse, strike-slip

  4. Hanging wall Foot wall Normal Fault • caused by tension forces • rock above the fault moves down compared to the rock below the fault Hanging Wall – rock that is above the fault line Foot Wall – rock that is below the fault line

  5. Hanging wall Foot wall Reverse Fault • caused by compression forces • rock above the fault moves upward compared to rock below the fault.

  6. Strike-Slip Fault -Caused by shear forces, rock on either side of the fault moves past one another in opposite directions.

  7. Elastic Rebound • When rocks strain and then break, the broken pieces snap back. • Potential energy builds up as the rocks deform over long periods of time. • Energy is suddenly released when the rocks break and move. • Movement causes vibrations

  8. Mountain Building • Fault-block Mountains

  9. Mountain Building • Folded Mountains Syncline – Maryland road cut (I-68)

  10. Mountain Building • Folded Mountains Anticline – Route 55 in West Virginia

  11. Parts of an Earthquake Focus – point inside earth where movement along a fault first occurs and energy is released Epicenter – the point on the Earth’s surface located directly above the focus.

  12. Seismic Waves • Primary waves– cause rock to move back and forth in the same direction other waves are moving • Secondary waves– cause rock to vibrate at right angles to the direction the waves are moving • Surface waves– slowest, largest, most destructive

  13. Shadow Zone

  14. Seismograph • Instrument that records an earthquake’s vibrations. • Richter scale – measures an earthquake’s size, or magnitude. 10 is the greatest.

  15. Tsunamis

  16. Earthquake Zones

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