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Volcanoes and Volcanism

GLY 2010 – Summer 2015 – Lecture 8

Eruption of Mt. Vesuvius, Italy

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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

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Pyroclastic Eruptions

• Magma spews upward with great force through a central vent

Left: Mt. St. Helens, 1980

Right: Kilauea, Hawaii

Fissure Eruptions Video

4 Iceland's Bardarbunga volcano system

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Fissure Image

• Eruptive fissure on southeast rim of Kilauea caldera, Hawaii

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Fissure Eruption

• Mauna Loa Volcano, Hawaii

Lava Flow Video

• Kilauea, Hawaii, July 13, 2007 7

Flowing Lava Video

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Columbia River Flood Basalt

• Imnahu River Canyon

• Photo: Stephen Reidel

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Columbia River Flood Basalt

• Grande Ronde Basalt

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Pillow Basalt

Pillow Flow, Hawaii

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Pillow Deltas

Undersea Volcano Eruptions

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Birth of an Island

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Vesicles

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Scoria

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Lava Tube or Tunnel

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Nahuku Lava Tube

• Thurston (Nahuku) lava tube

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

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Lava Tube, Hawaii

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Lava-Sicles

• Ape Cave, Mt. St. Helens

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Andesite Volcanoes

• Nevado Ojos del Salado, Chile /Argentina frontier

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Andesite Lava Flow and Dome

Volcan Láscar (Chile)

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Rhyolitic Lava

• San Francisco Peaks stratovolcano, Arizona

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

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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

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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

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Volcanic Ash Fall

• Mount Pinatubo (Philippines - 1991)

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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

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Krakatau Volcano• Located in the Sunda

strait between the islands of Java and Sumatra

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Krakatau, 1883 Eruption

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

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Tephra Effects

• Rabaul Town and Harbor after eruption Rabaul Town and

Harbor before eruption

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Tephra Effects

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

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Tephra Effects

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

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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"

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Mt. Pelée, Martinique

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Location of Mt. Pelée

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Eruption of Mt. Pelée

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Mt. Pelée Nuée Ardente

Photograph of a pyroclastic flow by Heilprin, 1902

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St. Pierre After Eruption• Photograph of

the remains of St. Pierre by Heilprin, 1902

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Later Eruption• Ash cloud above

Mt. Pelée

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

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Mt. Pelée Now

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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

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Mt. Fuji, Japan

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Arenal Volcano, Costa Rica

45Movies of the eruption of Mt. Ruapehu, New Zealand, 1995

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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.

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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

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Effusive Eruptions

• Shield

• Central vent

• Fissure

• Submarine

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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)

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Hawaiian Shield Volcanoes

These are the largest volcanoes on Earth

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Mauna Loa

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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

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Vent and Steam Explosion

• Mt. St. Helens

Viscosity and Lava Video

• The viscosity of lava affects lava properties

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A’a block flow, Kilauea, Hawaii

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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

Pahoehoe Flow Video

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Fire Fountains, Kilauea Video

• Kilauea eruption, February 9-10, 2005 58

Eyjafjallajökull

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• 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

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• 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

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Age of Submarine Lava

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

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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)

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Oceanic Volcanoes

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Areal Distribution of Volcanoes

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Prediction of Volcanic Eruptions

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