Geol101 2009Lect05 Volcanos - West Virginia Universitypages.geo.wvu.edu/~kite/Geol101_2009Lect05_Volcanos.pdf · (Lava Lamp) Volcanoes: ... ©2000 Haggerty Enterprises, Inc., Chicago,

GEOL 101 Lecture 5Dr. J. Steven Kite

West Virginia University

Volcanoes

““VolcanoVolcano””

19791979 Songs You Know by HeartSongs You Know by Heart

Jimmy Jimmy

BuffettBuffett

Spring Study Abroad Fair

Office of International Programs invites students to

WVU’s 2009 Spring Study Abroad Fair10 a.m.-4 p.m. Jan. 28

Mountainlair ballrooms.The fair will feature study abroad programs,

and faculty leaders and OIP staff will be on hand to answer questions. There will be door prizes

Start Working on Test Questions are available on my web

sitehttp://www.geo.wvu.edu/~kite/teaching.htm

Bring “Magma Chamber”(Lava Lamp)

Volcanoes:• Composition of Magma:

Important To Nature of Volcanic Eruptions and Resulting Landforms.

3 Eruption Types:

• Gaseous: Few Landforms• Explosive: Viscous Magma -• Effusive: Fluid Magma -Basaltic - Lava

3 Eruption Types:

• Gaseous: Few Landforms

Explosive Eruption:

Pyroclastics

Pinatubo, Philippines

1991

Fluid BasalticLava FlowMauna Loa, March 1983

Magma Viscosity Analog

2 Types of Eruption Apertures:

•Fissures•Vents

Basaltic Fissure Eruption, Hawaii 1983

Popocatepetl, Mexico: 1994

Fissure Eruptions• Basaltic: Fluid Lava

– Flood Basalts With Many Feeder Dikes; Basalt Plateaus

Columnar Jointing

Columnar Jointing, Yellowstone NP Lava Flow• J.S. Kite Photo, 2008

Dry Falls, Washington

Vent Eruptions = True Volcanoes

Basaltic Eruptions: Fluid Lava

• Shield Volcano (Hawaiian) -Flank Eruptions

• Hawaii 33,000 ft Relief; Olympus Mons = 80,000 ft

• Late Eruptions from MaficMagma Chamber may be Viscous

Basaltic Shield VolcanoMauna Kea, Hawaii

Shield Volcano

Basaltic Lava Flow

Shield Volcano: Mauna Loa, Hawaii

Mauna Loa Central Vent, Mauna Kea in Distance

Kupaianaha Shield, 1986

Pu’u O’o Lava Tube, 1992

Lava Tube, Hawaiian Volcanoes

National Park

Pu’u O’o - Royal Gardens Aa Flow 1983

Kilauea Eruptions 1983-Date

181 Houses Destroyed13 km of Road Buried

Pu’u O’o - Royal Gardens Aa Flow 1983

Kupaianaha Flow Meets Pacific, 1988

Rhyolitic Eruptions:Viscous Magma &

Pyroclastics

• Cinder Cones• Lava Domes• Minor Lava Flows

Tavurvur Volcano, New Guinea: Cinder Cone, Pyroclastics

Ashfall, Papua New Guinea, 1994

Cinder Cone: Mt. Etna, Italy

Viscous (Rhyolitic) Magma

Post-1980 Lava Dome

Mt. St. Helens

May Occur in Late Eruption Phases of Intermediate Magma Chamber

Intermediate (Andesitic) Magma:

Composition Varies -Viscous to Fluid• Small Cinder Cones & Flows

Grow into....• Composite Cones

(=Stratovolcanos) –Composite of Flows & Pyroclastics

Soufriere Hills

VolcanoMontserrat

Plymouth, Montserrat, July 1997

Bethel, Montserrat, July 1997

Mt. St. Helens, Spirit Lake

America’s Most Perfect Volcano

Mt. St. Helens, April 1980 Bulge

Mt. St. Helens Pyroclastics

1980

New Spirit Lake

Blast Zone of Mt. St. Helens

Eruption Casualty

Mt. Rainier & Tacoma, WA

Popocatepetl, Mexico: 1994

Popocatepetl, Mexico: Dec 2000

Caldera:Collapse of Magma Chamber

Positive Feed Back System:Lower Pressure = Eruption;Eruption = Lower Pressure

• Krakatoa 1883 • Mt. Mazama - Crater Lake

Crater Lake: Caldera of Mt Mazama

Caldera Eruptions• Welded Sheet of Tephra Includes

Ash, Bombs etc.

Mt. MazamaTephra orPyroclastics

Aniakchak Caldera, Alaska

Erosion -• Volcanic Neck Usually More

Resistant To Erosion • Erosion often Simultaneous

with Eruption -–Complex Forms

Shiprock, New Mexico

http://www.lavaworld.com/cfm/catalog/productlist.cfm©2000 Haggerty Enterprises, Inc., Chicago, Illinois

Magma Chamber Model

Pluton

• Igneous Intrusion–May Not Connect to Volcanos

• Large Pluton Cool Very Slow -Coarse-Grained Rx

• Small Plutons Cool Rapidly -Fine Grained Rx

Igneous Plutons

Plutons• Batholith - Huge• Stock - Big• Dike - Across Country Rock Layering• Sill - Parallel Country Rock Layering• Laccolith - Igneous “Blister”• Pipe or Neck- Feeder Tube

Igneous Plutons

Igneous Dikes

Finger Mountain Sill Jurassic “Basalt”

Upper Taylor Glacier, Antarctica ~ 200 m thick

intruded into Sandstone

Photo: Bernard M.Gunn, 1959www.geokem.com/images/pix/G-FDOL.jpg

See Web for Copyrighted Image

Devils Tower, Wyoming: Eroded Laccolith, J.S. Kite Photo, 2006

Long Valley Batholith & Dikes