Plate Tectonics and Earthquakes Objectives: Students will learn key terms associated with Students will learn key terms associated with plate tectonic.

Plate Tectonics and EarthquakesPlate Tectonics and EarthquakesPlate Tectonics and EarthquakesPlate Tectonics and Earthquakes

Objectives:Objectives:

• Students will learn key terms associated withStudents will learn key terms associated with plate tectonic processes.plate tectonic processes.

• Students will understand the specific motionsStudents will understand the specific motions associated with divergent, convergent, andassociated with divergent, convergent, and transform plate boundaries.transform plate boundaries.

• Students will gain a global view of EQ’sStudents will gain a global view of EQ’s (where EQ’s typically occur).(where EQ’s typically occur).

• Students will evaluate and apply conceptsStudents will evaluate and apply concepts from lab parts A, B, and C to answer criticalfrom lab parts A, B, and C to answer critical thinking questions. thinking questions.

Objectives:Objectives:

• Students will learn key terms associated withStudents will learn key terms associated with plate tectonic processes.plate tectonic processes.

• Students will understand the specific motionsStudents will understand the specific motions associated with divergent, convergent, andassociated with divergent, convergent, and transform plate boundaries.transform plate boundaries.

• Students will gain a global view of EQ’sStudents will gain a global view of EQ’s (where EQ’s typically occur).(where EQ’s typically occur).

• Students will evaluate and apply conceptsStudents will evaluate and apply concepts from lab parts A, B, and C to answer criticalfrom lab parts A, B, and C to answer critical thinking questions. thinking questions.

Continental Drift vs. Plate Tectonics – The DebateContinental Drift vs. Plate Tectonics – The Debate

Alfred WegenerAlfred Wegener

1912- observed thepossible fit betweenSo. America and Africa.

1912- observed thepossible fit betweenSo. 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 stalkof the science world – WHY?

Wegener became the laughing stalkof the science world – WHY?PangaeaPangaea

Continental Drift vs. Plate Tectonics – The DebateContinental Drift vs. Plate Tectonics – The DebateMid-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?

PaleomagnetismPaleomagnetism --- the evidence that the sea floor is active --- the evidence that the sea floor is active and moving (by the late 1960’s)and moving (by the late 1960’s)PaleomagnetismPaleomagnetism --- the evidence that the sea floor is active --- the evidence that the sea floor is active and moving (by the late 1960’s)and moving (by the late 1960’s)

PaleomagnetismPaleomagnetism: : paleopaleo (past) (past) magnetismmagnetism (magnetic) (magnetic)• past magnetism of lava flows are past magnetism of lava flows are recorded on recorded on the sea floorthe sea floor

• Iron in magma will point to the Iron in magma will point to the current current north pole. Evidence shows north north pole. Evidence shows north pole pole switches location to the south pole switches location to the south pole over over geologic time (magnetic reversals).geologic time (magnetic reversals).

PaleomagnetismPaleomagnetism: : paleopaleo (past) (past) magnetismmagnetism (magnetic) (magnetic)• past magnetism of lava flows are past magnetism of lava flows are recorded on recorded on the sea floorthe sea floor

• Iron in magma will point to the Iron in magma will point to the current current north pole. Evidence shows north north pole. Evidence shows north pole pole switches location to the south pole switches location to the south pole over over geologic time (magnetic reversals).geologic time (magnetic reversals).

North reversalNorth reversalNorth reversalNorth reversal South reversalSouth reversalSouth reversalSouth reversalcreating magnetic reversals on bothcreating magnetic reversals on bothsides of the plate (pattern of stripes)sides of the plate (pattern of stripes)creating magnetic reversals on bothcreating magnetic reversals on bothsides of the plate (pattern of stripes)sides of the plate (pattern of stripes)

magnetic patternmagnetic pattern 13

The Plate Tectonic ModelThe 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.

EarthquakePatterns

VolcanismPatterns

lithospherelithosphere

Asthenosphere (upper mantle)Asthenosphere (upper mantle)

Plate BoundariesPlate Boundaries• plates move relative to one anotherplates move relative to one another

• all major interactions of deformation occur at all major interactions of deformation occur at plate boundariesplate boundaries

• most volcanic and EQ activities occur at plate boundariesmost volcanic and EQ activities occur at plate boundaries

• three (3) distinct types of boundariesthree (3) distinct types of boundaries

Plate BoundariesPlate Boundaries• plates move relative to one anotherplates move relative to one another

• all major interactions of deformation occur at all major interactions of deformation occur at plate boundariesplate boundaries

• most volcanic and EQ activities occur at plate boundariesmost volcanic and EQ activities occur at plate boundaries

• three (3) distinct types of boundariesthree (3) distinct types of boundaries

Divergent Boundary – plates move AWAY from each otherDivergent Boundary – plates move AWAY from each other

Convergent Boundary – plates move TOWARD each otherConvergent Boundary – plates move TOWARD each other

Transform Boundary – plates SLIDE past each otherTransform Boundary – plates SLIDE past each other

Divergent Boundary:Divergent Boundary:

• plate material separatingplate material separating

Divergent Boundary:Divergent Boundary:

• plate material separatingplate material separating

ocean plate divergence Extensional forcescreate EQ’s

continental divergence

Extension createsfaulting

• Earthquake activity• Earthquake activity

Ocean-ContOcean-ContOcean-ContOcean-Cont Ocean-OceanOcean-OceanOcean-OceanOcean-Ocean Cont-ContCont-ContCont-ContCont-Cont

Convergent Boundary:Convergent Boundary:• interaction of two plates moving toward one anotherinteraction of two plates moving toward one another making contact– hence, collision or convergencemaking contact– hence, collision or convergence

• collisions produce earthquakes, volcanic activity, andcollisions produce earthquakes, volcanic activity, and crustal deformationcrustal deformation

Convergent Boundary:Convergent Boundary:• interaction of two plates moving toward one anotherinteraction of two plates moving toward one another making contact– hence, collision or convergencemaking contact– hence, collision or convergence

• collisions produce earthquakes, volcanic activity, andcollisions produce earthquakes, volcanic activity, and crustal deformationcrustal deformation

Subduction zone

Subduction zone SubductioinSubductioin

zonezoneSubductioinSubductioin

zonezoneOregon-Washington

CoastOregon-Washington

CoastAleutian Island(Alaska area)

Aleutian Island(Alaska area)

Himalayan MountainsHimalayan Mountains

ocean-continentocean-continent

ocean-oceanocean-ocean

cont-contcont-cont

• thinner and more dense platethinner and more dense plate subductssubducts• subducted plates melt (160 km)subducted plates melt (160 km) below the surface, and magmabelow the surface, and magma risesrises• EQ’s occur along the subductionEQ’s occur along the subduction zone, and magma plumes risezone, and magma plumes rise

• thinner and more dense platethinner and more dense plate subductssubducts• subducted plates melt (160 km)subducted plates melt (160 km) below the surface, and magmabelow the surface, and magma risesrises• EQ’s occur along the subductionEQ’s occur along the subduction zone, and magma plumes risezone, and magma plumes rise

• typically, the older plate will typically, the older plate will subduct (more dense) beneath subduct (more dense) beneath younger plate materialyounger plate material

• melting plate material rises,melting plate material rises, creating volcanic arc systemscreating volcanic arc systems

• most EQ’s occur within themost EQ’s occur within the subduction zonesubduction zone

• typically, the older plate will typically, the older plate will subduct (more dense) beneath subduct (more dense) beneath younger plate materialyounger plate material

• melting plate material rises,melting plate material rises, creating volcanic arc systemscreating volcanic arc systems

• most EQ’s occur within themost EQ’s occur within the subduction zonesubduction zone

• two plates converge with thetwo plates converge with the same densitysame density

• same density prevents same density prevents subductionsubduction

• extensive deformationextensive deformation

• two plates converge with thetwo plates converge with the same densitysame density

• same density prevents same density prevents subductionsubduction

• extensive deformationextensive deformation

• Earthquake activity• 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

SAFSAF

Transform boundaries offsettingspreading ridges

• Typical EQ’s occur along the transform boundary.

Transform boundaries offsettingspreading ridges

• Typical EQ’s occur along the transform boundary. EarthquakesEarthquakes

Cross-sectional view of the SAFand associated LA faults

•SAF – transform motion•LA faults- vertical motion

Cross-sectional view of the SAFand associated LA faults

•SAF – transform motion•LA faults- vertical motion SAF-transform faultSAF-transform fault

Los AngelesLos 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 Only a Model – Think ConvectionConvectionOnly a Model – Think Only a Model – Think ConvectionConvection

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 risesHot water rises

Cooler water sinksCooler water sinks

RiseRise

FallFall

Earth CrustEarth Crust

mantlemantlemantlemantle

The Earth’s MantleThe Earth’s MantleCan you see the convection?Can you see the convection?

Mantle operates like a “lava lamp,” producingMantle operates like a “lava lamp,” producingswelling and shrinking of magma plumes.swelling and shrinking of magma plumes.

Mantle operates like a “lava lamp,” producingMantle operates like a “lava lamp,” producingswelling and shrinking of magma plumes.swelling and shrinking of magma plumes.

Earth’s Surface

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• 0o latitude = equator• 0o latitude = equator

Longitude:• meridian lines that move east and west

Longitude:• meridian lines that move east and west • 0o longitude is through Greenwich, England• 0o longitude is through Greenwich, England 11

Los Angeles, Ca 350 N-lat, 1210 W-longLos Angeles, Ca 350 N-lat, 1210 W-longSpokane, Wa 470 N-lat, 1180 W-longSpokane, Wa 470 N-lat, 1180 W-longNew York, NY 420 N-lat, 750 W-longNew York, NY 420 N-lat, 750 W-long 12

A

B

C

DE

15 N-lat, 132 W-long15 N-lat, 132 W-long

52 N-lat, 78 E-long52 N-lat, 78 E-long

18 S-lat, 162 W-long18 S-lat, 162 W-long55 S-lat, 15 W-long55 S-lat, 15 W-long

25 S-lat, 136 E-long25 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.