Download Geos 432-4 Volcanic landforms

GEOS 432-4; Volcanic processes and landforms
Plate Tectonics and Volcanism

Mantle hot spots

Oceanic

Continental


Basaltic
Rhyolitic, andesitic, or
Rhyolitic,
basaltic
Plate tectonics and Volcanism

Plate margins

Divergent--basaltic
Divergent

Subduction of oceanic
plate--andesite
plate
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Large scale landforms
Submarine volcanoes
Large scale landforms
Basalt plateaus
Volcanic Products
Gas
 Lava
 Tephra

2
Gas

Vents

Hot springs, geysers, fumaroles, solfataras
Hot springs
Solfatara, Iceland
Geyser, ―Strokkur‖ at
Geysir, Iceland
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1
3
2
4
Mud volcano

http://ngm.nationalgeographic.com/ngm/20
08--01/volcano
08
01/volcano--culture/drowning
culture/drowning--in
in-mud.html
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
Lake Nyos case history

http://perso.wanadoo.fr/mhalb/nyos/index.htm
Lava

Composition


Silica content: 35% (basalt) – 75% (rhyolite,
obsidian)
Viscosity
Related to compositioncomposition-higher silica—
silica—more
viscous
 Temp and volatile content also important

 Volatiles
 Basalt
decrease viscosity but degas at surface
1100--1200 degrees C
1100
Lava flows
Vesicles
Pahoehoe lava
lava
AAAa
flow,
Iceland
Aa lava flow
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Rhylolite/obsidian flow
Obsidian
Columnar jointing
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Pillow lavas
Tephra



Ash—sand size &
Ash—
smaller
Lapilli—
Lapilli
—gravel
Blocks (Cold) Bombs
(warm)
Pumice, 1875 eruption of Askja, Iceland
1875 Snow exposed
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Pyroclastic eruptions
Heimaey, Iceland, 1973
2010 Eruption: Eyjafyallajökull
http://www.youtube.com/watch?v=f1ztg0wUqKY
Pyroclastic flow or surge
High temperature, very fast, very destructive
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Mt. Pelee, 1902
Town of St. Pierre, Carribean Island of Martinique 30,000 killed
Mt. St. Helens, 1980
Lateral Blast
Debris flows, Mt. St. Helens
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Mt St. Helens
Lahars
Orting, Washington
Mt. Rainier
Mt. Shasta
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Armero,, Nevado del Ruiz, 1985
Armero
23,000 people killed
Volcanic landforms
L
a
v
a
Lava flow
Exogenous dome
Shield volcano
Shield volcano
Shield volcano
Scoria
cone
Scoria
conecone
Scoria
Scoria
Scoria
conecone
Tuff ring
Endogenous dome
Ruptured ED
Composite (strato) volcano
Explosion caldera
Maars with tephra Maar with rampart
Collapse caldera
Gas maar
Explosion crater
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Lava flows—
flows—fissure or central vent
Young lava flow, Iceland
Fissures, Iceland
Iceland
Lava Cascade, Iceland
Fissure, Craters of the Moon
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Basalt flow Craters of the Moon
Miocene basalt flows from fissuresColumbia River Plateau
Exogenous domes
Spatter cone-Iceland
Shield Volcano-Iceland
Mauna Loa, as seen from Kilauea
Mauna Loa from Kilauea
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Pyroclastic cones, rings
Tuff ring, northern Iceland
Scoria cone
Tuff cone
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Tuff Ring, Iceland
Lake Myvatn, Iceland
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Endogenous domes
Mt. St. Helens
Composite (strato) volcanoes
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Mt. Fuji
Craters, calderas
Maar, New Mexico
Crater Lake
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Halemaumau pit crater
Summit caldera, Askja Volcano, Iceland
Santorini, Greece
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Miscellaneous
Icelandic
Mountain-Tuya
Icelandic
TableTable
Mountain
Tuya, Iceland
Miscellaneous con’t
Lava tube
Tumuli
Volcanic neck
Tree mold
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