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Geology 105 - Dynamic Earth Test Questions with
Correct Answers Fully Solved
viscosity - (answers)internal resistance to flow; may be low, medium, or high, and
it controls whether magma flows away or piles up
volatiles - (answers)chemical species that under normal conditions of pressure
and temperature exist in the gaseous phase; may be low, medium or high and
may ooze out harmlessly or blast out explosively
volume - (answers)may be small, medium or large; correlates fairly well with
eruption intensity; the greater the volume, the more intense the eruption
decompression melting - (answers)Melting caused by a decrease in pressure;
most of the rock that melts to form magma does so b/c the pressure on it
decreases, not b/c more heat is added
icelandic volcanoes - (answers)nonexplosive eruptions; low water content, low
viscosity; basalt
Hawaiian volcanoes - (answers)nonexplosive eruptions; low water content and
viscosity; basalt
Examples: Kilauea, 1971 "Fire-Fountaining" (Molten magma is ejected from cracks
to produce fire fountains that jet the lava 30 -50 feet into the air), Kilauea Iki,
1959, Puu Oo, 1984
, 2
Strombolian volcanoes - (answers)somewhat explosive; moderate water content,
low to moderate viscosity; basalt to andesite
Ex: The island of Stromboli, Mount Etna, Sicily.
vulcanian volcanoes - (answers)explosive eruption, steam-blasts; moderate to
high water content, moderate to high viscosity; basalt to rhyolite
Ex: Mount St. Helens
plinian volcanoes - (answers)the largest, most violent, and most destructive of all
eruptions; high water content and viscosity; andesite to rhyolite
Ex: Lassen Volcano, California, 1915, Mount Redoubt, Alaska, 1990, Pinatubo
Volcano Philippines, 1991
pyroclastic - (answers)gas blasting into the atmosphere takes along chunks of
magma and older rocks
pahoehoe - (answers)a smooth, ropy surface; tends to be more fluid (low
viscosity)
aa - (answers)rough, blocky surface; slow moving, higher viscosity; thick flows
pillow lava - (answers)ellipsoidal masses formed in water; thicker flows than aa
obsidian - (answers)cooled volcanic glass; nonporous glass
Geology 105 - Dynamic Earth Test Questions with
Correct Answers Fully Solved
viscosity - (answers)internal resistance to flow; may be low, medium, or high, and
it controls whether magma flows away or piles up
volatiles - (answers)chemical species that under normal conditions of pressure
and temperature exist in the gaseous phase; may be low, medium or high and
may ooze out harmlessly or blast out explosively
volume - (answers)may be small, medium or large; correlates fairly well with
eruption intensity; the greater the volume, the more intense the eruption
decompression melting - (answers)Melting caused by a decrease in pressure;
most of the rock that melts to form magma does so b/c the pressure on it
decreases, not b/c more heat is added
icelandic volcanoes - (answers)nonexplosive eruptions; low water content, low
viscosity; basalt
Hawaiian volcanoes - (answers)nonexplosive eruptions; low water content and
viscosity; basalt
Examples: Kilauea, 1971 "Fire-Fountaining" (Molten magma is ejected from cracks
to produce fire fountains that jet the lava 30 -50 feet into the air), Kilauea Iki,
1959, Puu Oo, 1984
, 2
Strombolian volcanoes - (answers)somewhat explosive; moderate water content,
low to moderate viscosity; basalt to andesite
Ex: The island of Stromboli, Mount Etna, Sicily.
vulcanian volcanoes - (answers)explosive eruption, steam-blasts; moderate to
high water content, moderate to high viscosity; basalt to rhyolite
Ex: Mount St. Helens
plinian volcanoes - (answers)the largest, most violent, and most destructive of all
eruptions; high water content and viscosity; andesite to rhyolite
Ex: Lassen Volcano, California, 1915, Mount Redoubt, Alaska, 1990, Pinatubo
Volcano Philippines, 1991
pyroclastic - (answers)gas blasting into the atmosphere takes along chunks of
magma and older rocks
pahoehoe - (answers)a smooth, ropy surface; tends to be more fluid (low
viscosity)
aa - (answers)rough, blocky surface; slow moving, higher viscosity; thick flows
pillow lava - (answers)ellipsoidal masses formed in water; thicker flows than aa
obsidian - (answers)cooled volcanic glass; nonporous glass
