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Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak ©2008 W. W. Norton & Company, Inc. Portrait.

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1 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak ©2008 W. W. Norton & Company, Inc. Portrait of a Planet Third Edition earth LECTURE OUTLINE Chapter 9 The Wrath of Vulcan: Volcanic Eruptions

2 Prepared by Ronald Parker Earlham College Department of Geosciences Richmond, Indiana Prepared by Ronald Parker Earlham College Department of Geosciences Richmond, Indiana

3 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Eruptions  What is a volcano?  An erupting vent through which molten rock surfaces.  A mountain built from magmatic eruptions.  Volcanoes are a clear result of tectonic activity.  Volcanoes pose a number of hazards to humans.  Mexico City.  Seattle, U.S.  Naples, Italy.

4 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak  In 79 C.E. Mt. Vesuvius erupted violently.  Pyroclastic flows destroyed Pompeii, killing 20,000.  A record of Roman life was preserved under ash. Volcanic Eruptions

5 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Eruptions  Unpredictable, dangerous.  Build large mountains.  Blow mountains to bits.  Eruptions can…  Provide highly productive soils to feed a civilization.  Can extinguish a civilization in a matter of minutes.  Eruptions affect climate.

6 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Materials  The products of volcanic eruption take three forms:  Lava flows – Molten rock that move over the ground.  Pyroclastic debris – Fragments blown out of a volcano.  Volcanic gases – Vapor and aerosols that exit a volcano.

7 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Lava Flows  Lava can be thin and runny or thick and sticky.  Flow type depends on viscosity via composition.  Composition depends on silica (SiO 2 ), Fe, and Mg.

8 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Lava Compositions  Lavas with high silica / low Fe and Mg are called...  Silicic, felsic, or rhyolitic.  Lavas with low silica / high Fe and Mg are called…  Mafic or basaltic.  Lavas with moderate silica, Fe and Mg are called…  Intermediate or andesitic.

9 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Basaltic Lava Flows  Mafic lava – Very hot, low silica, and low viscosity.  Basalt flows are often thin and fluid.  They can flow rapidly (up to 100 km/hr).  They can flow for long distances (up to several 100 km).

10 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Pahoehoe  Pahoehoe (pa-hoy-hoy) - a Hawaiian word describing basalt with a glassy, ropy texture.  Pahoehoe forms when extremely hot basalt forms a skin.  With flow, the skin is rolled into ropy ridges and furrows.

11 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak A’a’  A’a’ (ah-ah) is a Hawaiian word describing basalt that solidifies with a jagged, sharp, angular texture.  A’a’ forms when hot flowing basalt cools and thickens.  With flow, lava crumbles into shards and fragments.

12 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Lava Tubes  A cooled crust forms on top of a basalt flow.  A conduit – a lava tube – develops in the flow.  Tubes prevent cooling, facilitating flow for miles.  Lava tubes become caves that can transmit water.

13 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Columnar Jointing  Solidified flows may contract with vertical fractures that are hexagonal in cross-section.  Columnar jointing indicates lava.

14 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Pillow Basalts  Underwater, basalt cools instantly; it cannot flow.  It cools to form a rounded blob called a pillow.  The pillow surface is cracked, quenched glass.  Lava pressure ruptures a pillow to form the next blob.  The process repeats to form a mound of pillow basalts.  Common on the MOR.

15 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Andesitic Lava Flows  Higher SiO 2 content makes andesitic lavas viscous.  Unlike basalt, they do not flow rapidly.  Instead, they mound around the vent and flow slowly.  The outer crust fractures, creating rubble.  Andesitic lava flows remain close to the vent.

16 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Rhyolitic Lava Flows  Rhyolite; the highest SiO 2 – the most viscous lava.  Rhyolitic lava rarely flows.  Rather, lava plugs the vent as a lava dome.  Sometimes, lava domes are blown to smithereens.

17 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Pyroclastic Debris  Fragmental material ejected from a volcano.  Glass shards, fragmented lava in a range of sizes.  Ash – Powdery glass shards.  Lapilli – Pea- to plum-sized material.  Blocks and bombs – Apple- to refrigerator-sized.  Blocks – Pre-existing rock torn from the volcano.  Bombs – Streamlined fragments of ejected lava.

18 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Pyroclastic Debris  Tephra – Deposits of pyroclastic debris.  Volcanic agglomerate – Lapilli and bombs near the vent.  Tuff – Lithified ash with or without lapilli.  Air-fall tuff – Accumulations of ash that fall like snow.  Welded tuff (ignimbrite) – Tuff that is deposited while hot.  Hot pyroclastic flow material that fuses before cooling.

19 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Pyroclastic Flows  Pyroclastic flows (or, nuée ardentes - French):  200 o C o C avalanches of hot ash that race downslope.  Moving up to 300 kph, they incinerate all in their path.  Immediately deadly; they kill everything quickly.  Many famous examples: Vesuvius, Mt. Pelée, Augustine.

20 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Lahars  Tephra is readily moved by water as a debris flow.  Known as lahars, these flows are often deadly.  Lahars move rapidly (up to 50 km/hr).  They have the consistency of wet cement,.  A distinct hazard to people living in volcanic valleys.

21 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Gas  1 to 9% of magma may be gas.  Water (H 2 O) – Most abundant dissolved gas.  Carbon dioxide (CO 2 ) – Second in abundance.  Sulfur dioxide (SO 2 ) – Rotten egg smell.  Magma composition controls gas content.  Felsic magmas are gas-rich; Mafic magmas are less so.

22 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Gas  Gases are expelled as magma rises (P drops).  SO 2 reacts with water to form aerosol sulfuric acid.  Style of gas escape controls eruption violence.  Low viscosity (basalt) – Easy escape; mellow eruption.  High viscosity (rhyolite) – Difficult escape; violent.  Gas bubbles in rock are called vesicles.

23 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Architecture  Volcanoes have characteristic features.  A magma chamber.  Fissures and vents.  Craters.  Calderas.  Distinctive profile.

24 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Magma Chamber  Located in the upper crust.  Usually an open cavity or area of highly fractured rock.  Contains a large quantity of magma.  Some magma cools here to form intrusive rock.

25 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Magma Chamber  Some magma rises via a conduit to the surface.  Magma may also erupt along a linear tear, a fissure.  Fissure eruptions may display a “curtain of fire.”  Fissures evolve into discrete vents.

26 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Vents  A vent is a lava outlet on a volcano.  Vents can form anywhere on the volcano.  Summit vent – Located at the top of the volcano.  Flank vent – Located on the side of a volcano.

27 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Craters  Crater – A bowl-shaped depression atop a volcano.  Craters are up to 500 m across; 200 m deep.  Form as erupted lava piles up around the vent.  Accentuated by summit collapse into conduit.

28 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Caldera  A gigantic volcanic depression.  Much larger than a crater.  1-10s of kilometers across.  Magma chamber empties.  Volcano collapses into it.  Crater Lake, Oregon.  Yellowstone National Park.

29 Crater Lake Caldera, Oregon

30 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Shapes and Sizes  Magma type governs volcano shape and size.  Categories:  Shield volcanoes – Largest.  Cinder cones – Smallest.  Stratovolcanoes – Intermediate in size.

31 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcano Types  Shield volcanoes.  Broad, slightly domed-shaped (like an inverted shield).  Lateral flow of low-viscosity basaltic lava.  Have a low slope and cover large geographic areas.  Mauna Loa on Hawaii is a good example.

32 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcano Types  Cinder cone – Conical piles of tephra.  The smallest type of volcano.  Built of ejected lapilli-sized fragments piled up at a vent.  Slopes are at the angle of repose.  Often symmetrical with a deep summit crater.

33 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcano Types  Stratovolcanoes (composite volcanoes).  Large, cone-shaped volcano.  Composed of alternating layers of lava and tephra.  Often symmetric; can be odd shapes from landslides, etc.  Examples include Mt. Fuji, Mt. Rainier, Mt. Vesuvius.

34 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Eruptive Style  Will it flow, or will it blow? Two dominant styles.  Effusive eruptions – Produce lava flows.  Explosive eruptions – Blow up.

35 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Eruptive Style  Effusive eruptions – Produce lava flows.  Lava flows stream away from vents.  Lava lakes can form around the vent.  Can produce huge lava fountains.  Commonly basaltic, these eruptions create shields.

36 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Eruptive Style  Explosive eruptions – Produce pyroclastic flows.  Caused by gas pressure in the more viscous magma.  Pressure is released explosively.  Create stratovolcanoes.  May create calderas.  Blanket the landscape with tephra.  Andesitic and rhyolitic compositions.

37 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Eruptive Style  Phreatomagmatic eruptions – Less common style.  Volcanic eruption where magma interacts with water.  Some phreatomagmatic eruptions can be cataclysmic.  A magma chamber breaches and admits water.  Water flashes to steam and blows the entire volcano apart.  Examples: Santorini, Krakatau.

38 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Controls on Eruptive Style  Viscosity – Controls the ease of lava flow.  Basalt – Low-viscosity lava flows away from vent.  Felsic – High-viscosity lava builds-up at the vent.  Gas Pressure – Greater P favors explosive style.  Basalt – Low-viscosity allows gas release.  Felsic – High-viscosity prevents gas release.  Environment – Where eruption occurs important.  Subaerial lava flowing on land cools slower than…  Submarine lava, which is quickly quenched.

39 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Eruptions to Remember  Mt. St. Helens – Erupted May 18, 1980, 8:32 A.M.  Earthquake-triggered landslide released pressure.  Initial vertical blast followed by a much stronger lateral blast that tore off the entire north side.  396 m was blasted away.

40 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Eruptions to Remember  Mt. St. Helens – Erupted May 18, 1980, 8:32 A.M.  The blast devastated 600 km 2 and killed 61 people.  Lahars plugged the Toutle River; closed the Columbia.  Ash fell in North Dakota; highways and rail lines stopped.  Destroyed timber valued at several $100 million.

41 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Tectonic Settings  Plate motion is a dominant control on volcanism.  Volcanic types are linked to tectonic settings  Hot spots - Where mantle plumes cut the lithosphere.  Oceanic hot spots.  Continental hot spots and flood basalts.  Mid-ocean ridges – Spreading axes.  Convergent boundaries – Subduction zones.  Continental rifts – Incipient ocean basins.

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43 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Hot Spot Eruptions  Oceanic hot spot – Plume under an oceanic plate.  Basalt erupts at the seafloor and forms a growing mound.  A volcano builds above sea level to form an island.  Then basalt will not quench and can flow long distances.  Lava builds upward and outward and the island grows.  Submarine slumps remove large masses of the volcano.

44 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Hot Spot Eruptions  Continental hot spot – Cuts a continental plate.  Often erupts both basaltic and rhyolitic material.  Basaltic – Makes up the mantle plume.  Rhyolitic – Basalt melts the granitic crust it passes through.

45 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Hot Spot Eruptions  Continental hot spots.  Yellowstone – Eruption 640 ka created a 100 km caldera.  1000 times more powerful than Mt. St. Helens.  Deposited 10s of m of ignimbrites.  Magma beneath the caldera still fuels geysers.  Heads a hot spot track.

46 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Hot Spot Eruptions  Continental hot spots.  Flood basalts – Voluminous lava eruption above a plume.  Thinned lithosphere erupts magma from long fissures.  Lava spreads over large areas; great thicknesses stack up.  With time, a shrinking plume creates “normal” volcanoes.

47 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak MOR Eruptions  Most lava erupts along the mid-ocean ridge (MOR).  MOR-produced oceanic crust covers 70% of Earth.  Basalt erupted from fissures quenches as pillows.  Pillow mounds are pulled apart with plate motion.

48 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Iceland  Iceland is a hot spot beneath the MOR.  Lava has built the hot spot/ridge above sea level.  The island is being torn apart by plate motion.  Volcanoes trace the MOR rift.

49 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Convergent Boundaries  Most volcanoes form at convergent boundaries.  Volatiles from subducting plate initiate melting.  Arc volcanoes develop on overriding plate.  May cut through oceanic or continental crust.  The “Ring of Fire” dominates Pacific margins.

50 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Continental Rifts  Yield an array of volcano types reflecting...  Partial melting of the mantle (mafic magmas).  Partial melting of the crust (felsic magmas).  Examples:  East African Rift.  Basin and Range.  Mid-continent Rift.

51 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Volcanic eruptions cause great harm to humans.  Eruptions have profoundly influenced human history.  In the past 2,000 years: an estimated 250,000 deaths.  Many populated areas ring active volcanoes.  More humans live in volcano hazard areas than ever.  Understanding volcanic behavior is the best defense.

52 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Lava flows – Lava threats are mostly from basalt.  Lava may completely destroy immovable objects.  It is rare for lava flows to kill people.  Usually there is enough notice.  Lava rarely moves faster than people.  Sometimes people watching lava flows are killed.

53 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Tephra – Ash and lapilli fall around the volcano.  Can completely bury landscapes, killing plants and crops.  Tephra is heavy; it causes roof collapses.  Tephra is gritty; it abrades car and airplane engines.  Floodwaters easily move tephra as deadly lahars.

54 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Pyroclastic flows – aka nuée ardente  Clouds of roiling ash and gas that race downslope.  Ride over a carpet of superheated air.  Eases passage of the flow.  Permits high velocities.  Immediately deadly to anything living.

55 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Blast – Rarely, explosions are ejected sideways.  Mt. St. Helens – Lateral blast tore off north side.  Destroyed over 600 km 2 of forest.  Killed 61 people.  Blast hazard is uncommon; most eruption is vertical.

56 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Landslides – Eruption-related slope failures.  Eruptions can trigger landslides.  Large masses of material are deposited rapidly near vent.  Earthquakes initiate failure of unstable slopes.  Mt. St. Helens.  The eruption immediately followed a 3 km 3 slope failure.  Slide material moved more than 20 km from the peak.

57 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Lahars – Mudflows result when water moves ash.  Like concrete, this material is more dense than water.  It can carry away everything (people, houses, bridges).  Nevada del Ruiz, Colombia, buried Armero +25,000 people.

58 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Earthquakes – Moving magma causes earthquakes.  Although usually small in magnitude, they are frequent.  Can cause slope failures and damage to structures.  Tsunamis – Water explosions create giant waves.  Tsunamis from Krakatau (1883) killed 36,000.

59 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanic Hazards  Gas – Volcanic gases can be poisonous (H 2 S, CO 2 ).  Lake Nyos, Cameroon,  Magmatic CO 2 built up in the lake located in a crater.  The lake overturned (burped) and the CO 2 …  Moved down the valleys as a heavier-than-air underflow.  Killed 1,742 people; 6,000 cattle.

60 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Active vs. Extinct  Recurrence interval – Average between eruptions.  Active – Erupting, recently erupted or likely to erupt.  Dormant – Volcano that has not erupted in 100s to 1000s of years (but could still do so).  Extinct – No longer capable of erupting.  Tectonic changes can shut off the magma “fuel.”  After extinction, erosion takes over.

61 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Predicting Eruptions  Warning signs precede most eruptions.  Earthquake activity – Magma flow increases seismicity.  Heat flow – Magma causes volcanoes to “heat-up.”  Changes in shape – Magma causes expansion.  Emission increases – Changes in gas mix and volume.  These signs indicate that an eruption is imminent.  They cannot predict the exact timing or the style.

62 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Mitigating Hazards  Danger assessment maps.  Delineate danger areas.  Pyroclastic flows.  Lahars.  Landslides.  Used for planning, zoning.

63 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Mitigating Hazards  Evacuation – Moving those at high risk saves lives.  Mt. St. Helens – Timely evacuation saved 100s.  Sometimes eruptions don’t occur, large expenses.  Diverting flows – Flowing lava can be diverted.  Explosives.  Heavy equipment.  Seawater.

64 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanoes and Climate  Volcanic aerosols and fine-debris block sunlight.  Examples of volcanism affecting climate  Mt. Tambora, Indonesia – 1815  Pinatubo, Philippines – 1991  Makes for more intense sunsets.

65 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanoes and Civilization  Humans and volcanoes have coexisted for millenia.  This coexistence has both bad and good facets.  Volcanic soils are highly fertile; excellent for crops.  Civilizations have prospered and been erased.  Minoans - Santorini

66 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak Volcanoes on Other Planets  Volcanic activity evident on the Moon and planets.  Lunar maria (dark “seas”) are regions of flood basalts.  Olympus Mons – Extinct Martian shield volcano.  The Jovian moon Io has active volcanoes.

67 Chapter 9: The Wrath of Vulcan: Volcanic Eruptions Earth: Portrait of a Planet, 3 rd edition, by Stephen Marshak ©2008 W. W. Norton & Company, Inc. Portrait of a Planet Third Edition earth LECTURE OUTLINE Chapter 9 The Wrath of Vulcan: Volcanic Eruptions This concludes the


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