1 / 22

GEOL: CHAPTER 8

GEOL: CHAPTER 8. Earthquakes and Earth’s Interior. Learning Outcomes. LO1: Explain Elastic Rebound Theory LO2: Describe seismology LO3: Identify where earthquakes occur, and how often LO4: Identify different seismic waves LO5: Discuss how earthquakes are located. Learning Outcomes, cont.

roosevelt-erling
Download Presentation

GEOL: CHAPTER 8

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GEOL: CHAPTER 8 Earthquakes and Earth’s Interior

  2. Learning Outcomes LO1: Explain Elastic Rebound Theory LO2: Describe seismology LO3: Identify where earthquakes occur, and how often LO4: Identify different seismic waves LO5: Discuss how earthquakes are located

  3. Learning Outcomes, cont. LO6: Explain how the strength of an earthquake is measured LO7: Describe the destructive effects of earthquakes LO8: Discuss earthquake prediction methods LO9: Discuss earthquake control methods

  4. Learning Outcomes, cont. LO10: Describe Earth's interior LO11: Examine Earth's core LO12: Examine Earth's mantle LO13: Describe Earth's internal heat LO14: Examine earth's crust

  5. Earth’s Interior • Crust • Mantle • Outer core • Inner core

  6. Seismic Waves and Earth’s Interior • P-wave and S-wave velocity determined by density and elasticity of material • S-waves don’t travel through liquids • Seismic waves change velocity and direction when enter material with different density or elasticity (refraction)

  7. Seismic Waves and Earth’s Interior, cont. • Some waves are reflected • Calculate depths of boundaries • Discontinuity: significant change in materials or their properties

  8. The Core • P-wave velocity decreases at a depth of 2,900 km: core-mantle discontinuity • P-wave shadow zone • Weak P-wave energy does penetrate the shadow zone: from solid inner core • S-wave shadow zone: shows the outer core is liquid, because S-waves can’t travel through liquids

  9. Core Density and Composition • 16.4% Earth volume • ~33% of mass • Outer core: 9.9 to 12.2 g/cm3 • Earth center: pressure 3.5 million times of surface • Outer core: iron, sulfur, silicon, oxygen, nickel, potassium • Inner core: iron and nickel

  10. Earth’s Mantle • Moho: discontinuity about 30 km deep • Asthenosphere: • 100-250 km deep • P- and S-waves slow down • Plastic • Magma generation • Lithospheric plates ride across it • 3.3 to 5.7 g/cm3; probably periodotite

  11. Earth’s Internal Heat • Geothermal gradient: 25ºC/km • Greater in active volcanic regions • Most heat generated by radioactive decay • Regions of equilibrium temperature • Base of crust: 800ºC to 1200ºC • Core-mantle boundary: 2,500ºC -5,000ºC

  12. Continental Crust • Granitic composition • 2.5 to 3.0 g/cm3; average = 2.7 g/cm3 • 20 to 90 km thick; average = 35 km thick • Thickest under large mountain ranges

  13. Oceanic Crust • Gabbro overlain by basalt • Average density = 3.0 g/cm3 • 5-10 km thick • Thinnest at spreading ridges

More Related