Title: Geology THIRD EDITION by Stanley Chernicoff University of Washington, Seattle Donna L' Whitney Unive
1EARTH STUDIES Geosciences 1000
VOLCANOES OTHER IGNEOUS ACTIVITY Chapter 6
2SHIELD 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
3VOLCANIC LANDFORMS
- Shield Volcanoes
- Relative Size
4Kilauea Eruptions (Hawaii) courtesy USGS
5Kilauea September 15, 2002
Courtesy USGS
6Kilauea, Sept. 19, 2002
Courtesy USGS
7Kilauea, Sept. 20, 2002
Courtesy USGS
8Kilauea, Sept. 20, 2002
Courtesy USGS
9Kilauea September 20, 2002
Courtesy USGS
10Courtesy USGS
Hawaii - Kilauea September 13, 2002
11TRUE or FALSE
This is Pahoehoe Type Lava
Courtesy USGS
Hawaii - Kilauea September 13, 2002
12Hawaii Empty School Bus Engulfed by Basaltic
Flow
13MARS 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
14MARS 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)
15VOLCANIC LANDFORMS
Laki Today
Fissure Flows
Thingvellir Graben, Iceland Mid-Atlantic Ridge
Exposed at the Surface
16VOLCANIC 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
17COMPOSITE 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
18VOLCANIC LANDFORMS
- Shield Volcanoes
- Relative Size
19VOLCANIC LANDFORMS
20COMPOSITE CONES STRATOVOLCANOES
Stromboli Volcano Italy Lighthouse of the
Mediterranean
Recent Eruption
- Composite Cones European Classification
21Basaltic Lava Flows Are Generally Associated with
- Cinder Cones
- Shield Volcanoes
- Composite Cones
- Fissure Flows
- Stratovolcanoes
- Both B and D
22CINDER 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
Sunset Volcano Near Flagstaff, Arizona
23VOLCANIC LANDFORMS
- Shield Volcanoes
- Relative Size
24CINDER 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
25PUG 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
26CRATERS VS. CALDERAS
- Craters - Constructional
- Calderas - Collapse
Crater Lake, Oregon
Sunset Volcano Near Flagstaff, AZ
27VOLCANIC LANDFORMS
Crater Lake, Oregon
28Mt. 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.
29VOLCANIC LANDFORMS
Crater Lake, Oregon
OTHER CALDERAS Santorini Krakatoa
Yellowstone (3 overlapping calderas)
Kilauea, Hawaii
30TRUE or FALSE
- Another Name for a Stratovolcano
- Is
- Composite Cone Volcano
31VOLCANICLANDFORMSLAHARS(Mass Wasting)
32LAHAR 1980 Mt. St. Helens
33Lahar 1985 - Nevado del Ruiz, Columbia
Town of 23,000 people buried by 40m wall of
mud 50 km from summit of volcano
34TRUE or FALSE
- Crater Lake
- Got Its Name Because It Is Formed
- in the Crater of an Ancient Volcano
35Warning 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
36Future Volcanic Activity Its not If Its Whe
n
Mt. Rainier on the Seattle, WA Skyline
37DANGER-ASSESSMENT MAP Mt. Rainer area Different
Colors indicate different types of hazards Some
Lahars threaten the City of Tacoma, Washington
38p.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
39VOLCANIC LANDFORMS
40EARTH STUDIES Geosciences 1000
VOLCANOES OTHER IGNEOUS ACTIVITY Chapter 6