Geology THIRD EDITION by Stanley Chernicoff University of Washington, Seattle Donna L' Whitney Unive - PowerPoint PPT Presentation

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Geology THIRD EDITION by Stanley Chernicoff University of Washington, Seattle Donna L' Whitney Unive

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Title: Geology THIRD EDITION by Stanley Chernicoff University of Washington, Seattle Donna L' Whitney Unive


1
EARTH STUDIES Geosciences 1000
VOLCANOES OTHER IGNEOUS ACTIVITY Chapter 6
2
SHIELD VOLCANOES - Hawaii
Hawaiian Islands 5 Merged Shield Volcanoes 6,000
m (20,000) from Ocean Floor to Sea Level 4,000 m
(13,000) Above Sea Level
Hot Fluid Basaltic Lava Little Pyroclastic
Material Low Profile Gently Sloping Sides Thin
Individual Flows (Ribbons) Rapid Accumulation of
Flows
Mauna Loa 10,000 m (33,000) from Ocean Floor 10
km diameter at base
3
VOLCANIC LANDFORMS
  • Shield Volcanoes
  • Relative Size

4
Kilauea Eruptions (Hawaii) courtesy USGS
5
Kilauea September 15, 2002
Courtesy USGS
6
Kilauea, Sept. 19, 2002
Courtesy USGS
7
Kilauea, Sept. 20, 2002
Courtesy USGS
8
Kilauea, Sept. 20, 2002
Courtesy USGS
9
Kilauea September 20, 2002
Courtesy USGS
10
Courtesy USGS
Hawaii - Kilauea September 13, 2002
11
TRUE or FALSE
This is Pahoehoe Type Lava
Courtesy USGS
Hawaii - Kilauea September 13, 2002
12
Hawaii Empty School Bus Engulfed by Basaltic
Flow
13
MARS Olympus Mons Volcano Enormous Shield Volcano
large enough to cover most of the northeastern
section of the United States
Artists rendition, Based on images from NASAs
Viking mission to Mars
14
MARS Olympus Mons Volcano on Mars Would Be
Associated with What Type of Lava?
A. Andesite B. Basalt C. Rhyolite D.
None (Its on Mars Not Earth)
15
VOLCANIC LANDFORMS
Laki Today
Fissure Flows
  • Fissure Flows - Iceland

Thingvellir Graben, Iceland Mid-Atlantic Ridge
Exposed at the Surface
16
VOLCANIC LANDFORMS
Multiple Lava Flows Snake River Plain
  • Fissure Flows Columbia Basalt Plateau

Hot Fluid Basaltic Lava Little Pyroclastic
Material Thin Individual Flows Rapid Accumulation
of Flows
17
COMPOSITE CONES
  • Vesuvius, Mt. Pele St. Pierre, Martinique
  • Santorini, Tambora, Krakatoa, Mt. St. Helens

Mt. Shasta Cascade Range Northern California Last
Erupted 1855
Felsic/Intermediate - High Viscosity
Lava Layered Lava and Pyroclastic Flows Explosive
Gas - Nuee Ardentes Located At Convergent
Plate Boundaries and Continental Hot Spots
18
VOLCANIC LANDFORMS
  • Shield Volcanoes
  • Relative Size

19
VOLCANIC LANDFORMS
  • Composite Cones

20
COMPOSITE CONES STRATOVOLCANOES
Stromboli Volcano Italy Lighthouse of the
Mediterranean
Recent Eruption
  • Composite Cones European Classification

21
Basaltic Lava Flows Are Generally Associated with
  • Cinder Cones
  • Shield Volcanoes
  • Composite Cones
  • Fissure Flows
  • Stratovolcanoes
  • Both B and D

22
CINDER CONES
  • Paricutin
  • - Highly viscous lava clogs vent
  • - Pyroclastic (cinder) fragments form
  • steep-sided cone at maximum
  • angle of repose (25-35o)
  • Lava flows break-out at base of
  • weak cinder cone

Sunset Volcano Near Flagstaff, Arizona
23
VOLCANIC LANDFORMS
  • Shield Volcanoes
  • Relative Size

24
CINDER CONES
  • - Highly viscous lava clogs vent
  • - Pyroclastic (cinder) fragments form
  • steep-sided cone at maximum
  • angle of repose (25-35o)
  • Lava flows break-out at base of
  • weak cinder cone

SP Crater - North of Flagstaff, Arizona
25
PUG DOMES
  • Present Day Mt. St. Helens

- Rhyolite Lava - Oozes Out on Ground Like Thick
Toothpaste - Piles-up Steep-sided Domes -
Typically Obsidian and Pumice - Irregular Summit
Surface
26
CRATERS VS. CALDERAS
  • Craters - Constructional
  • Calderas - Collapse

Crater Lake, Oregon
Sunset Volcano Near Flagstaff, AZ
27
VOLCANIC LANDFORMS
  • Craters and Calderas

Crater Lake, Oregon
28
Mt. MazamaExtentofAsh Fall
Near Crater Lake, Oregon
Ash and Pumice ejected from the Mt. Mazama
eruption. Prior to the eruption, magma began to
segregate as silica-rich, less dense magma
migrated toward the top of the magma chamber. The
light and dark zonation occurred as the eruption
tapped deeper and deeper portions of the magma
chamber that were less silica- rich.
29
VOLCANIC LANDFORMS
  • Craters and Calderas

Crater Lake, Oregon
OTHER CALDERAS Santorini Krakatoa
Yellowstone (3 overlapping calderas)
Kilauea, Hawaii
30
TRUE or FALSE
  • Another Name for a Stratovolcano
  • Is
  • Composite Cone Volcano

31
VOLCANICLANDFORMSLAHARS(Mass Wasting)
32
LAHAR 1980 Mt. St. Helens
33
Lahar 1985 - Nevado del Ruiz, Columbia
Town of 23,000 people buried by 40m wall of
mud 50 km from summit of volcano
34
TRUE or FALSE
  • Crater Lake
  • Got Its Name Because It Is Formed
  • in the Crater of an Ancient Volcano

35
Warning Signs of a Volcanic Eruption(Long term
poor Short term reasonably precise)
  • Increased heat as magma rises
  • Hot springs
  • Surface of volcano
  • Increasing gas emissions (Steam, CO2, SO4)
  • Expansion of volcano
  • Bulging, Swelling (tilt meters)
  • Harmonic tremors (earthquakes)
  • Infrared Remote Sensing newly heated areas
  • Magnetic, Electrical, Gravitational changes

36
Future Volcanic Activity Its not If Its Whe
n
Mt. Rainier on the Seattle, WA Skyline
37
DANGER-ASSESSMENT MAP Mt. Rainer area Different
Colors indicate different types of hazards Some
Lahars threaten the City of Tacoma, Washington
38
p.194-195a
Ash and tephra
VOLCANOES
Explosive eruption
Volcanic bombs
Side vent
Pyroclastic flow(nuée ardente)
Eroded cone
Old lava dome
Mud flows (older)
Sequentialash and lavalayers
Lava cone
Lavas
Sills
Lava flow
Sedimentary rocks
Fracturing
Dikes
  • original artwork by Gary Hincks

Laccolith
Cinder cones
Lava pavement(cracked/broken)
Metamorphic rocks
Contact metamorphism
Chimney
Graniteintrusion (older/cold)
Magma chamber
39
VOLCANIC LANDFORMS
  • Summary - Handout

40
EARTH STUDIES Geosciences 1000
VOLCANOES OTHER IGNEOUS ACTIVITY Chapter 6
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