1

Volcanoes and Volcanism

GLY 2010 – Summer 2012 – Lecture 8

Eruption of Mt. Vesuvius, Italy

2

Volcano

• A vent in the surface of the Earth through which magma and associated gases and ash erupt

• Also, the form or structure, usually conical, that is produced by the ejected material

• Plural: volcanoes

• Etymology: the Roman deity of fire, Vulcan

3

Pyroclastic Eruptions

• Magma spews upward with great force through a central vent

Left: Mt. St. Helens, 1980

Right: Kilauea, Hawaii

4

Fissure Eruptions Video

• Volcanic eruptions may occur much more quietly along long cracks in the ground

5

Fissure Image

• Eruptive fissure on southeast rim of Kilauea caldera, Hawaii

6

Fissure Eruption

• Mauna Loa Volcano, Hawaii

Lava Flow Video

• Kilauea, Hawaii, July 13, 2007 7

8

Flowing Lava Video• (Upper left)Lava falls Kilauea,

Hawaii

• (Lower left) Fissure eruptions, Hawaii (with sound)

• (Below) Lava flow damage (with sound)

9

Columbia River Flood Basalt

• Imnahu River Canyon

• Photo: Stephen Reidel

10

Columbia River Flood Basalt

• Grande Ronde Basalt

11

Pillow Basalt

12

Pillow Flow, Hawaii

• Click video to play

13

Pillow Deltas

14

Vesicles

15

Scoria

16

Lava Tube or Tunnel

17

Nahuku Lava Tube

• Thurston (Nahuku) lava tube

• Near summit caldera of Kilauea Volcano, Hawaii Volcanoes National Park

18

Lava Tube, Hawaii

19

Lava-Sicles

• Ape Cave, Mt. St. Helens

20

Andesite Volcanoes

• Nevado Ojos del Salado, Chile /Argentina frontier

21

Andesite Lava Flow and Dome

Volcan Láscar (Chile)

22

Rhyolitic Lava

• San Francisco Peaks stratovolcano, Arizona

• Sugarloaf Mountain, the small dome-shaped hill in the foreground, is a rhyolite dome

23

Tephra• General term for fragments of

volcanic rock and lava that, regardless of size, are blasted into the air by explosions or carried upward by hot gases in eruption columns or lava fountains

24

Tephra Eruption

• The Puu Oo cone, the main vent for Kilauea from 1983-1986, is made of cinder and spatter from numerous lava fountains

• Photograph by J.D. Griggs, U.S. Geological Survey

25

Volcanic Ash Fall

• Mount Pinatubo (Philippines - 1991)

26

Effect on Climate• Large volcanic eruptions can block a great

deal of the sun’s energy from reaching the earth’s surface

• This cools the climate until the tephra particles sink to the surface

27

Krakatau Volcano• Located in the Sunda

strait between the islands of Java and Sumatra

28

Krakatau, 1883 Eruption

Sunset, Chelsea, London, 11/26/1883 William Ascroft

29

Tephra Effects

• Rabaul Town and Harbor after eruption Rabaul Town and

Harbor before eruption

30

Tephra Effects

• The village of Galunggung, Indonesia, buried in volcanic ash

31

Tephra Effects

• Trees covered with volcanic ash near Mount St. Helens, Washington

32

Nuée Ardente

• A swiftly flowing, turbulent gaseous cloud, sometimes incandescent, erupted from a volcano and containing ash and other pyroclastics in its lower part; a density current of pyroclastic flow

• Etymology: French, "glowing cloud"

33

Mt. Pelée, Martinique

34

Location of Mt. Pelée

35

Eruption of Mt. Pelée

36

Mt. Pelée Nuée Ardente

Photograph of a pyroclastic flow by Heilprin, 1902

37

St. Pierre After Eruption• Photograph of

the remains of St. Pierre by Heilprin, 1902

38

Later Eruption• Ash cloud above

Mt. Pelée

• Photograph of Mt. Pelée by Heilprin, August 30, 1902

39

Mt. Pelée Now

40

Stratovolcano

• A volcano that is constructed of alternating layers of lava and pyroclastic deposits, along with abundant dikes and sills

• Synonym: composite volcano; composite cone

41

Mt. Fuji, Japan

42

Arenal Volcano, Costa Rica

43Movies of the eruption of Mt. Ruapehu, New Zealand, 1995

44

Crater Lake, Oregon

Crater Lake National Park, with Wizard Island Cinder Cone

• Crater Lake, despite the name, is a caldera, formed after the eruption of ancient Mt. Mazama about 6600 y.b.p.

45

Crater Lake National Park, with Wizard Island Cinder Cone

Cinder Cone

• Wizard Island, within Crater Lake, is a cinder cone, and one of the tallest in the world

46

Effusive Eruptions

• Shield

• Central vent

• Fissure

• Submarine

47

Shield Volcano

• A volcano in the shape of a flattened dome, broad and low, built by flows of very fluid basaltic lava or by rhyolitic ash flows

• Shield volcanoes are the largest volcanoes on Earth that actually look like volcanoes (i.e. not counting flood basalt flows)

48

Hawaiian Shield Volcanoes

These are the largest volcanoes on Earth

49

Mauna Loa

50

Volcanic Vent Image

• Small lava fountain erupts from a new vent on the flank of Pu`u `O`o spatter and cinder cone on the east rift zone of Kilauea Volcano, Hawaii

51

Vent and Steam Explosion

• Mt. St. Helens

Viscosity and Lava Video

• The viscosity of lava affects lava properties

52

53

A’a block flow, Kilauea, Hawaii

• December, 2000 Several times the lava tubes choked up and lava broke out on the steep southern slope

• These breakouts sent Aa flows charging down the slope, taking out new swaths of trees on the eastern end of the flowfield

(Video – click to play)

54

Kilauea Lava Entering Water Videos

• By Steve O'Meara of Volcano Watch International

• Hot lava shooting out of lava flow wall, like water from a firehose, from Volcanovideo

55

Kilauea Eruption Videos•(Upper left) Explosive eruptions

•(Center left) Gas bubbles splash lava over the edges (with sound)

•(Lower left) Lava flowing after initial surge

•(Right) Upwelling lava – note rapid change in color – yellow is hottest, then orange, and red is the coolest

56

Pahoehoe Flow

• Toes of a pahoehoe flow advance across a road in Kalapana on the east rift zone of Kilauea Volcano, Hawaii

• Photograph by J.D. Griggs on 16 July 1990

57

Pahoehoe “Toes”

• Small glowing pahoehoe toes were fed by lava that broke out from a lava tube (out of view) at Kilauea Volcano, Hawaii

• Photo: J.D. Griggs on 29 July 1985

58

Pahoehoe Flow Videos

• Pahoehoe flow videos, Kilauea, Hawaii

Fire Fountains, Kilauea Video

• Kilauea eruption, February 9-10, 2005 59

Eyjafjallajökull

60

• Increase in seismic activity from late 2009 through March 20, 2010, when initial eruption occurred

• A new eruption starting April 14, 2010 created an ash cloud which approached European air space, causing widespread closure of European airports and massive travel disruptions

• Eruption released 250,000,000 m3 of volcanic ash, to a height of 9000 m (30,000 feet)

• Fine ash created by lava and ice (in the caldera) reaction

Eyjafjallajökull Ash Cloud

61

• Composite map of the volcanic ash cloud spanning 14–25 April 2010•Many airports shut from April 15 to April 20•By some accounts, the largest disruption of European air travel since WWII

62

Age of Submarine Lava

• Contact between young pillow lavas erupted in mid-1980s and older lavas with light dusting of sediment

63

Volcanology As a Profession - Videos

• (Upper) Cindy from Volcanovideo taping a flow

• More than a dozen internationally known volcanologists were killed during the 1990’s

• (Lower) Volcanologists collecting samples from erupting volcano (with sound)

64

Oceanic Volcanoes

65

Areal Distribution of Volcanoes

66

Prediction of Volcanic Eruptions

• Man cannot stop subduction, or magma generation - therefore, the prediction of imminent eruption becomes very important