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Classroom presentations to accompany Understanding Earth, 3rd edition prepared by Peter Copeland and William Dupré University of Houston Chapter 5 Volcanism.

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Presentation on theme: "Classroom presentations to accompany Understanding Earth, 3rd edition prepared by Peter Copeland and William Dupré University of Houston Chapter 5 Volcanism."— Presentation transcript:

1 Classroom presentations to accompany Understanding Earth, 3rd edition prepared by Peter Copeland and William Dupré University of Houston Chapter 5 Volcanism

2

3 Fig. 5.1 Plumbing System of a Volcano

4 May 1990 Eruption of Kilauea, Hawaii James Cachero/Sygma

5 Volcanic rocks Major difference between plutonic and volcanic rocks is texture, a reflection of cooling rate.

6 Material ejected from volcanoes Nonvolatile material Lava: magma that has flowed on the surface of the Earth. Tephra: fragments that solidified in the air during eruption.

7 Types of Lava aapahoehoe

8 Kim Heacox/DRX Fig. 5.3 PahoehoeLava Aa Lava

9 Martin G. Miller Fig. 5.2 Columbia Plateau Flow Basalts

10 Tephra Pyroclastic flow Air-fall Mudflow (lahar)

11 Pyroclastic flow (nueé ardente) Mixture of hot gases, ash, and rocks forming a super-heated and dense current capable of moving 150 km/hr.

12 R.S.J. Sparks Pyroclastic Flow from the 1998 Eruption on Montserrat

13 AP/Wide World Photos Fig. 5.9 Escaping a Pyroclastic Flow at Mount Unzen, Japan, 1991

14 Science Source/Photo Researchers Fig. 5.7 Volcanic Bomb

15 Doug Sokell/Visuals Unlimited Fig. 5.8 Volcanic Breccia

16 Submarine eruptions Pillow basalt Phreatic explosions

17 Woods Hole Oceanographic Institute Fig. 5.4 Pillow Lava

18 Maritime Safety Agency, Japan Fig Phreatic Explosion in the Pacific

19 Glen Oliver/Visuals Unlimited Fig. 5.5 Vesicular Basalt

20 Gregory G. Dimijian/Photo Researchers Fig. 5.6 Pyroclasic Eruption at Arenal Volcano, Costa Rica

21 Eruptive styles and landforms Shield volcanoes Stratovolcanoes (composite) Domes and cones Fissure eruptions (flood basalts) Submarine eruptions

22 Shield volcanoes Low-viscosity lava flows –Low-silica magma — mafic –Basalt »Pahoehoe »Aa Gently sloping flanks — between 2 and 10 degrees Tend to be very large Spatter cone — minor feature

23 Shield Volcano Fig. 5.10

24 NASA, Viking Orbiter 1 Olympus Mons Shield Volcano

25 Cinder cones Formed of pyroclastics only Steep sides — ~30 degrees Relatively small Short duration of activity

26 Fig Cinder Cone

27 Mark Hurd Aerial Surveys Fig Cerro Negro Cinder Cone, near Managua, Nicaragua in 1968

28 Volcanic domes Forms above a volcanic vent Viscous lava — usually silica- rich (or cooler magma) Associated with violent eruptions

29 Fig. 5.11

30 P. L. Kresan Inyo Obsidian Domes-California

31 Lyn Topinka/USGS Fig Lava Dome

32 Composite volcano Alternating pyroclastic layers and lava flows Slopes intermediate in steepness Intermittent eruptions over long time span Mostly andesite Distribution –Circum-Pacific Belt (“Ring of Fire”) –Mediterranean Belt

33 Fig Composite Volcano

34 Raga/The Stock Market Fig Mt Fujiyama, Japan

35 Emil Muench/Photo Researchers Before May, 1980

36 David Weintraub/Photo Researchers After May, 1980

37 Caldera Depression at top of volcano produced during an eruption May have younger domes within it

38 Fig. 5.16

39 Greg Vaughn/Tom Stack Fig Crater Lake, Oregon

40 Fred Padula Fig Shiprock, New Mexico an exposed volcanic pipe (diatreme )

41 Fissure eruptions When low-viscosity lava is issued from cracks in the Earth tens of kilometers long.

42 1971 Fissure Eruption, Kilauea, Hawaii

43 Fig Fissure Eruptions Form Lava Plateaus

44 Tony Waltham Fig Laki fissure (Iceland) erupted in 1783 extruding the largest lava flow in human history.

45 Lava floods Mafic lava — solidifies to basalt Fissure flows –Plateau basalts Columnar structure or jointing

46 Fig. 5.22

47 Martin G. Miller Fig. 5.2 Columbia Plateau Flow Basalts

48 Welded Tuff: California Gerals and Buff Corsi/Visuals Unlimited Fig foot

49 S. Aramaki Fig Ash-flow Sheets Draping Topography, Japan

50 Caution: Volcanologist at Work Maurice Krafft/Photo Researchers Fig. 5.25

51 Volcanic Mudflow (lahar): A mixture of water and pyroclastic material in a concrete-like slurry capable of moving up to 100 km/hour!

52 Barbara and Robert Decker 23,000 killed in 1985 by volcanic mudflows, Nevada del Ruiz

53 Other material ejected from volcanoes Volatile material Steam (H 2 O) Carbon dioxide (CO 2 ) Hydrogen sulfide (H 2 S) Many other constituents

54 Christian Grzimek/Photo Researchers Fig Sulfur-encrusted fumerole: Galapagos Islands

55 Simon Fraser/Photo Researchers Fig Stokkur geyser in Iceland

56 Tectonic setting of volcanoes Convergent plate boundaries Divergent plate boundaries Within plate “hotspots”

57 The World’s Active Volcanoes Fig. 5.28

58 Fig Cross Section of the East Pacific Rise

59 Volcanism Associated with Plate Tectonics Fig. 5.30

60 Effects of volcanoes on humans Growth of Hawaii Geothermal energy Effect on climate Volcanic catastrophes »Mt. St. Helens »Vesuvius »Krakatoa »Mt. Pelée »Montserrat

61 Types of Volcanic Hazards Lava Flows: e.g. Hawaii, 1998 Gas: e.g. Lake Nyos (Cameroon), 1984 –1700 people killed Ash fall: e.g. Mt. Pinatubo, 1991 Pyroclastic flows: e.g. Mt. Pelee, 1902 –28,000 killed Lahars (mudflows): e.g. Nevado del Ruiz, 1985 –23,000 killed Tsunami: e.g. Krakatoa, 1883 –36,417 killed

62 E. Tad Nichols San Juan, Mexico, Buried by Paricutin Lava Flows

63 Roger Ressmeyer/Corbis Fig Scientists Investigate Mt. Pinatubo’s Caldera

64 U.S. Active Volcanoes


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