Download Volcano - West Virginia University

GEOL 101 Lecture 5
Dr. J. Steven Kite
West Virginia University
Volcanoes
“Volcano”
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Jim ett
Bu f f
1979
Songs You Know by Heart
Spring Study Abroad Fair
Office of International Programs
invites students to
WVU’s 2009 Spring Study Abroad Fair
10 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
site
http://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 Basaltic
Lava Flow
Mauna 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 Mafic
Magma Chamber may be Viscous
Basaltic Shield Volcano
Mauna 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 Destroyed
13 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
May Occur in Late Eruption Phases of
Intermediate Magma Chamber
Post-1980
Lava Dome
Mt. St. Helens
Intermediate (Andesitic) Magma:
Composition Varies Viscous to Fluid
• Small Cinder Cones & Flows
Grow into....
• Composite Cones
(=Stratovolcanos)
–Composite of Flows & Pyroclastics
Soufriere
Hills
Volcano
Montserrat
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. Mazama
Tephra or
Pyroclastics
Aniakchak Caldera, Alaska
Erosion • Volcanic Neck Usually More
Resistant To Erosion
• Erosion often Simultaneous
with Eruption –Complex Forms
Shiprock, New Mexico
Magma Chamber Model
http://www.lavaworld.com/cfm/catalog/productlist.cfm
©2000 Haggerty Enterprises, Inc., Chicago, Illinois
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
See Web for Copyrighted Image
Finger Mountain Sill
Jurassic “Basalt”
Upper Taylor Glacier, Antarctica
~ 200 m thick
intruded into Sandstone
Photo: Bernard M.Gunn, 1959
www.geokem.com/images/pix/G-FDOL.jpg
Devils Tower, Wyoming: Eroded Laccolith, J.S. Kite Photo, 2006
Long Valley Batholith & Dikes