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Earthquakes

Earthquakes

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Earthquakes

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Presentation Transcript

  1. Earthquakes Chapter 7

  2. Web Sites about Earthquakes • www.iris.edu • http://earthquake.usgs.gov/ For Fun • http://earthquake.usgs.gov/learn/facts.php

  3. Information We Need from Earthquakes (EQ) • EPICENTER (Latitude, Longitude) • FOCUS ( Hypocenter ) (Depth of the EQ) • How Big it was ? How much Energy? (Mercalli intensity vs Richter Magnitude) • What Kind it was? What type of Fault • How Long it was ?

  4. Epicenter vs. Hypocenter (Focus)

  5. Mercalli Intensity Scale vsRichter Magnitude • Mercalli Intensity is measured by means of the degree of damage to structures of human origin Based on (IsoseismalLines) Richter Magnitude (Inhabited and Uninhabited regions) • Seismic wave amplitudes measured by a seismograph • He replace numbers by their logarithms. so instead of using their amplitudes used the powers of the numbers

  6. Mercalli vs Richter Mercalli Richter Magnitude When a logarithmic scale every time the magnitude goes up by 1 unit, the amplitude of the earthquake waves is increased by 10 times Example 4 to 5 ( 10 times ) 4 to 6 (100 times) 4 to 7 (1000 times) • Map of intensities with isoseismal lines

  7. 2010 Chile EQ vs Haiti EQ Chile Earthquake Magnitude scale • www.usgs.gov

  8. Earthquakes Waves • Body Waves (P waves and S Waves) • Surface Waves ( Rayleigh and Love Waves) P-S Waves 3 Components seismograph

  9. Locating and Earthquake • We need at least 3 station to estimate the epicenter of an earthquake ! • What do seismologist need arrival times for P and S waves A simple formula is (S time – P time )x 8.2 = Distance in KM (Kilometers)

  10. Example

  11. Earthquakes in Plate Boundaries • Transform California USGS today • Convergent Example Chile Earthquake (Nazca Plate subducting in South-America Plate) • Divergent USGS website eq today

  12. Wadatti-Benioff Zone

  13. EQ prediction Earthquake Probability • Long-Term Prediction Probability • Short-term Prediction Foreshocks

  14. How Rock and Soil Influence Earthquake Damage • Mexico City Earthquake Example • Liquefaction Soils behave like liquid, Building Codes, Example Haiti Earthquake and Chile Earthquake

  15. Tsunamis • EQ summatra and Tsunami

  16. Structure of Earth

  17. Structure of Earth • shadow Zone