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© 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. https://www.ngdc.noaa.gov/mgg/image/images/g01167-pos-a0001.pdf © 2015 Pearson Education, Inc. Continental Crust Oceanic Crust felsic and low density “light and fluffy” thick and buoyant does not subduct mafic and high density “dark and dense” thin and sinks does subduct Mid-Ocean Ridge Aesthenosphere Subducting Slab old crust destroyed Mantle Upwelling Magma new crust added Tectonic plates “float” on the higher density mantle. © 2015 Pearson Education, Inc. The driving mechanism of plate tectonics is mantle convection. Hot mantle material rises at ridges and cooler mantle material sinks at subduction zones. © 2015 Pearson Education, Inc. Layer Volume (km^3) Inner Core 4,645,335 4% Outer Core 33,531,915 26% Mantle & Crust 89,338,868 70% 200,072 0.2% 1,596,180 1.3% Crust © 2015 Pearson Education, Inc. Magma Origins Lithosphere Asthenosphere © 2015 Pearson Education, Inc. PAGE 53 & ACTIVITY 2.9 How can you melt the material at “X”? © 2015 Pearson Education, Inc. ~750 C ~80 km & ~26,000 atm PAGE 53 & ACTIVITY 2.9 A-C © 2015 Pearson Education, Inc. Plate Boundaries © 2015 Pearson Education, Inc. EXAMPLE IN UNITED STATES? San Andreas Fault, Transform Boundary between North America and Pacific plates © 2015 Pearson Education, Inc. EXAMPLES AROUND WORLD? Dead Sea East African Rift Mid-Oceanic Ridges © 2015 Pearson Education, Inc. EXAMPLE IN UNITED STATES? Pacific and North American Plates, with Alleutian Islands © 2015 Pearson Education, Inc. EXAMPLE IN UNITED STATES? Pacific and North American Plates, with Cascade Mountains (Mt. St. Helens) © 2015 Pearson Education, Inc. EXAMPLES AROUND WORLD? Himalayan Mtns. Appalachian Mtns. (former) © 2015 Pearson Education, Inc. PAGE 61 ACTIVITY 2.4 © 2015 Pearson Education, Inc. Magnetic minerals (magnetite) that crystalize from lava align with the magnetic field of the Earth and are locked in place when the lava cools sufficiently (solidifies). Direction and angle (steep at poles, horizontal at equator) PAGE 61 ACTIVITY 2.4 © 2015 Pearson Education, Inc. Juan de Fuca & Gorda Plates vs. Pacific Plate © 2015 Pearson Education, Inc. PAGE 61 ACTIVITY 2.4.A (1-5) NO, not a straight line YES, curved line PAGE 63 ACTIVITY 2.5 © 2015 Pearson Education, Inc. p 52 & ACTIVITY 2.8 (p 68) A. 1-4 Activity A. 2. Change 20 to 40 Ma (m.y.) to 40 to 60 Ma (m.y.) © 2015 Pearson Education, Inc. Hot Spot: Rising plume or column of mantle material including magma, from deeper levels in the mantle, closer to core than magma created at divergent and convergent plate boundaries. Magma rises through oceanic plate creating volcanoes, that may reach sea level and above. © 2015 Pearson Education, Inc. Plate moves across Hot Spot, carrying the volcano away from the Hot Spot. New volcano forms above the Hot Spot. Youngest volcanic rock at the Hot Spot. Plate moves in the direction toward the older rock/volcanoes. © 2015 Pearson Education, Inc. Laboratory Manual in Physical Geology, 10e Image PPTs Chapter 16 Earthquake Hazards and Human Risks © 2015 Pearson Education, Inc. Fig. 16.04 © 2015 Pearson Education, Inc. Fig. 16.06 A seismograph measures relative movement of the ground to a stationary pen. Fig. 16.07 © 2015 Pearson Education, Inc. Body Waves Surface Waves © 2015 Pearson Education, Inc. Fig. 16.05 P or Primary Waves: • Compression/Expansion (“Sound”) • Solid and Liquid, through the Earth (Body Wave) S or Secondary Waves: • Transverse • Solid Only, through the Earth (Body Wave) Surface (Love/Raleigh) Waves: • Transverse/Circular (“Ocean”) • Solid Only, Near land surface © 2015 Pearson Education, Inc. Velocity ~ Density? Density ~ Depth? Seismogram – record of ground movement produced by a seismograph P-wave velocity will always be higher than S-wave velocity, no matter what the waves travel through. P-waves arrive at the station first, followed by S-waves and later by surface waves. Because S-waves travel more slowly than P-waves, the farther the waves have traveled, the farther behind the S-waves will be and the longer the time gap until they arrive. © 2015 Pearson Education, Inc. http://www.gly.uga.edu/railsback/GeologicalDiagrams1.html P or Primary Waves: Fastest – Arrives Two cars leave Rock Hill, Galleria Mall,First I-77 at the same time to Charleston. S or Secondary Waves: Middle Surface (Love/Raleigh) Waves: Slowest – Arrives Last(P Wave) One drives 60 mph (S Wave) and one drives 80 mph Time: 7:14 = 14 after 7 oclock At Columbia, 60minutes miles, 60 minutes & 45 minutes Difference Arrive Times Arrival timeindifference: 15between minutes the P and S Waves 7:17.4 – 7:14.2,240 ignore the3.75 7:00hours and 3 hours At Charleston, miles, Minutes 17.4 minutes – 14.2 minutes = ? 3.2 Arrival time difference: 0.75 hours or 45 minutes © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. SEISMOGRAPH #1 EARTHQUAKE SEISMOGRAPH #2 SLOW FAST SLOW SEISMOGRAPH #1: P-S Travel Time = 4.1 min, 2,000 km 2000/4.1 = 490 km/min 2 x 4.1 min = 8.2 min SEISMOGRAPH #2: P-S Travel Time = 7.2 min, 4,000 km 4000/7.2 = 560 km/min Velocity increases as depth increases © 2015 Pearson Education, Inc. Each line is representative of a particular type of seismic wave. Which is the fastest wave? Which is the next fastest wave? L Wave Why curved lines? Why straight line? S Wave P Wave © 2015 Pearson Education, Inc. Earthquake in Pacific Northwest Waves arrive in Denver distance: 2000 km Waves arrive in St. John’s distance: 5300 km Waves arrive in Lima distance: 9000 km Fig. 16.10 © 2015 Pearson Education, Inc. Fig. 16.09 The difference between the arrival times for P-waves and S-waves can be used to determine the distance to the earthquake’s epicenter © 2015 Pearson Education, Inc. PAGE 401 & ACTIVITY 16.3 P-Wave: 8:07.4 © 2015 Pearson Education, Inc. S-Wave: 8:11.5 11.5 – 7.4 = 4.1 minutes L Wave 4.1 minutes S Wave P Wave ~ 2,600 km © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. PAGE 403 & ACTIVITY 16.4 Right Lateral vs. Left-Lateral © 2015 Pearson Education, Inc. Strike-Slip Fault ACTIVITIES: 2.4.A: 1-5 2.5: All 2.8.A: 1-4 16.3: All 16.4: A, C © 2015 Pearson Education, Inc.