Plate Tectonics and Earthquakes

1. Plate Tectonics and Earthquakes • Objectives: • Students will learn key terms associated with • plate tectonic processes. (Part A) • Students will understand the specific plate • motions associated with divergent, • convergent, and transform plate boundaries. • (Part B) • Students will gain a global view of EQ’s • (where EQ’s typically occur). (Part C) • Students will evaluate and apply concepts • from lab parts A, B, and C to answer critical • thinking questions. (Part D)

2. The Plate Tectonic Model lithosphere Volcanism Patterns Asthenosphere (upper mantle) Earthquake Patterns • The plate tectonic model describes surface features, geologic • environments, and patterns of EQ’s and volcanism. • Ridged lithospheric plates (continents + ocean floor) ride • along the soft layer (like hot wax) called the asthenosphere • Plates spread apart, collide, and slide past one another. • EQ’s, crustal deformation, and volcanism take place at plate • boundaries.

3. Plate Boundaries Divergent Boundary – plates move AWAY from each other Convergent Boundary – plates move TOWARD each other Transform Boundary – plates SLIDE past each other

4. Divergent Boundary: • plate material separating • Earthquake activity Extensional forces create EQ’s ocean plate divergence continental divergence Extension creates faulting

5. Convergent Boundary: • interaction of two plates moving toward one another • making contact– hence, collision or convergence • collisions produce earthquakes, volcanic activity, and • crustal deformation Ocean-Cont Ocean-Ocean Cont-Cont Subduction zone Subductioin zone Oregon-Washington Coast Himalayan Mountains Aleutian Island (Alaska area)

6. thinner and more dense plate • subducts • subducted plates melt (160 km) • below the surface, and magma • rises • EQ’s occur along the subduction • zone, and magma plumes rise ocean-continent • Earthquake activity • typically, the older plate will • subduct (more dense) beneath • younger plate material • melting plate material rises, • creating volcanic arc systems • most EQ’s occur within the • subduction zone ocean-ocean • two plates converge with the • same density • same density prevents • subduction • extensive deformation cont-cont

7. Transform Boundary: • two plates are sliding past one another • lack the spectacular features associated with • divergent/convergent boundaries • marked by linear valleys (slices through the • earth’s crust) • shallow-focused EQ’s occur along the slip area of the • sliding plates SAF

8. Transform boundaries offsetting • spreading ridges • Typical EQ’s occur along • the transform boundary. Earthquakes • Cross-sectional view of the SAF • and associated LA faults • SAF – transform motion • LA faults- vertical motion SAF-transform fault Los Angeles

9. What moves or drives the plates? What could Wegener have told the geological society? Only a Model – Think Convection Convection – heat transfer through a liquid or gas that results in circular movement of particles Cooler water sinks Hot water rises

10. Earth Crust The Earth’s Mantle Can you see the convection? mantle mantle Convection Rise Fall

11. Earth’s Surface Mantle operates like a “lava lamp,” producing swelling and shrinking of magma plumes. 57

12. Latitude and Longitude • Where are you on earth? • Latitude/Longitude • a grid system used to locate features on • the earth’s surface • Latitude: • parallel lines that move north • and south • 0o latitude = equator • Longitude: • meridian lines that move east • and west • 0o longitude is through • Greenwich, England 11

13. Los Angeles, Ca 350 N-lat, 1210 W-long Spokane, Wa 470 N-lat, 1180 W-long 12 New York, NY 420 N-lat, 750 W-long

14. West East Latitude (+) Longitude (+) Latitude (+) Longitude (-) North Equator South Latitude (-) Longitude (-) Latitude (-) Longitude (+) Latitude ( Prime Meridian

15. 13 52 N-lat, 78 E long B 15 N-lat, -132 W-long A -25 S-lat, 136 E long D E -18 S-lat, -162 W-long -55 S-lat, -15 W-long C

16. Plate Tectonics Lab: • Part A: Plate tectonic definitions • use lab text • use textbook resources in classroom • Part B: Identification of plate boundaries • use lab text, colored pencils • use textbook resources in classroom • Part C: Plotting EQ location • use provided long/lat handouts • use colored pencils • Part D: Critical thinking questions • use parts A, B, and C and your • synthesizing brain.