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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) - PowerPoint PPT Presentation
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Plate Tectonics and EarthquakesObjectives:• 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)
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.
EarthquakePatterns
VolcanismPatterns
lithosphere
Asthenosphere (upper mantle)
Plate 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
ocean plate divergence Extensional forcescreate EQ’s
continental divergence
Extension createsfaulting
• Earthquake activity
Ocean-Cont Ocean-Ocean Cont-Cont
Convergent Boundary:• interaction of two plates moving toward one another
making contact– hence, collision or convergence• collisions produce earthquakes, volcanic activity, and
crustal deformation
Subduction zone Subductioin
zoneOregon-Washington
CoastAleutian Island(Alaska area)
Himalayan Mountains
ocean-continent
ocean-ocean
cont-cont
• 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• 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
• two plates converge with the same density• same density prevents subduction• 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
SAF
Transform boundaries offsettingspreading ridges
• Typical EQ’s occur along the transform boundary. Earthquakes
Cross-sectional view of the SAFand 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?
Only a Model – Think Convection
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
mantlemantle
The Earth’s MantleCan you see the convection?
Mantle operates like a “lava lamp,” producingswelling and shrinking of magma plumes.
Earth’s Surface
57
Latitude and Longitude• Where are you on earth?
Latitude/Longitude• a grid system used to locate features on
the earth’s surfaceLatitude: • 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
Los Angeles, Ca 350 N-lat, 1210 W-longSpokane, Wa 470 N-lat, 1180 W-longNew York, NY 420 N-lat, 750 W-long 12
Latitude (+)Longitude (-)
Latitude (-)Longitude (-)
EastWest
North
South
Latitude (+)Longitude (+)
Equator
Prime M
eridianLatitude (Latitude (-)Longitude (+)
A
B
C
DE
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.