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

Continental Drift vs. Plate Tectonics – The Debate Alfred Wegener observed the possible fit between So. America and Africa observed the possible fit between So. America and Africa. Hypothesized the continents were all together forming the supercontinent Pangaea – 250 million years ago Supported by the following evidence: fossil evidence lithologic evidence climatic evidence Hypothesized the continents were all together forming the supercontinent Pangaea – 250 million years ago Supported by the following evidence: fossil evidence lithologic evidence climatic evidence Wegener became the laughing stalk of the science world – WHY? Wegener became the laughing stalk of the science world – WHY? Pangaea

Continental Drift vs. Plate Tectonics – The Debate Mid-Atlantic Ridge 1947 – mapping of the ridge linear mountain range active EQ and volcanism area of sea floor spreading Mid-Atlantic Ridge 1947 – mapping of the ridge linear mountain range active EQ and volcanism area of sea floor spreading Sea Floor Spreading Magma rises in between the ocean floor (ridge). Magma pushes the ocean floor – spreading the floor apart. Sea Floor Spreading Magma rises in between the ocean floor (ridge). Magma pushes the ocean floor – spreading the floor apart. Can scientists actually see “spreading” of the ocean floor? How do scientists know the floor is actually moving? Can scientists actually see “spreading” of the ocean floor? How do scientists know the floor is actually moving?

Paleomagnetism --- the evidence that the sea floor is active and moving (by the late 1960’s) and moving (by the late 1960’s) Paleomagnetism --- the evidence that the sea floor is active and moving (by the late 1960’s) and moving (by the late 1960’s) Paleomagnetism: paleo (past) magnetism (magnetic) past magnetism of lava flows are recorded on the sea floor past magnetism of lava flows are recorded on the sea floor Iron in magma will point to the current north pole. Evidence shows north pole switches location to the south pole over geologic time (magnetic reversals). Iron in magma will point to the current north pole. Evidence shows north pole switches location to the south pole over geologic time (magnetic reversals). Paleomagnetism: paleo (past) magnetism (magnetic) past magnetism of lava flows are recorded on the sea floor past magnetism of lava flows are recorded on the sea floor Iron in magma will point to the current north pole. Evidence shows north pole switches location to the south pole over geologic time (magnetic reversals). Iron in magma will point to the current north pole. Evidence shows north pole switches location to the south pole over geologic time (magnetic reversals). North reversal South reversal creating magnetic reversals on both sides of the plate (pattern of stripes) creating magnetic reversals on both sides of the plate (pattern of stripes) magnetic pattern 13

The Plate Tectonic Model 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. 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. Earthquake Patterns Volcanism Patterns lithosphere Asthenosphere (upper mantle)

Plate Boundaries plates move relative to one another plates move relative to one another all major interactions of deformation occur at all major interactions of deformation occur at plate boundaries plate boundaries most volcanic and EQ activities occur at plate boundaries most volcanic and EQ activities occur at plate boundaries three (3) distinct types of boundaries three (3) distinct types of boundaries Plate Boundaries plates move relative to one another plates move relative to one another all major interactions of deformation occur at all major interactions of deformation occur at plate boundaries plate boundaries most volcanic and EQ activities occur at plate boundaries most volcanic and EQ activities occur at plate boundaries three (3) distinct types of boundaries three (3) distinct types of boundaries Divergent Boundary – plates move AWAY from each other Convergent Boundary – plates move TOWARD each other Transform Boundary – plates SLIDE past each other

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

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

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

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 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

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

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

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

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

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

Los Angeles, Ca 35 0 N-lat, W-long Spokane, Wa47 0 N-lat, W-long New York, NY42 0 N-lat, 75 0 W-long 12

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

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. 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.