GSC 103 NEW EXAM 2 WITH COMPLETE SOLUTIONS 100%
VERIFIED!!
What is a volcano? - ANSWER A volcano is a vent in the Earth's crust through which
magma, ash, and gases erupt.
Where do volcanoes occur? - ANSWER Volcanoes occur at divergent plate boundaries
where convective magma is rising to the surface, at convergent boundaries where
subducting crust is being partially melted, and at smaller hot spots. (Most volcanoes are
at the bottom of the sea)
What comes out of a volcano? - ANSWER Lava, rocks, and gases.
Effects of volcanic gas - ANSWER Volcanic carbon dioxide and chemical weathering are
the main controls on Earth's long-term (millions of years) climate. Volcanoes also emit
considerable amounts of sulfur dioxide. Sulfur also forms aerosols, which can cause
short-term(months to years) changes in climate.
Silicate in magmas - ANSWER Magma is composed almost entirely of metal silicate
minerals. Magma also contains 0.2%-3% dissolved gases, mostly water and carbon
dioxide. More silicate means higher viscosity. Because of this, basaltic magmas and
volcanoes will be distinctly different from andesitic and rhyolitic magmas and
volcanoes. Ocean hotspots and divergent boundaries produce basalt magmas, which
will be thin and runny. Continent hotspots and subduction zones will produce andesitic
and rhyolitic magmas, which will be thick and sticky.
Hawaiian Eruptions - ANSWER Low viscosity, basaltic magma causes non-explosive or
Hawaiian eruptions. (Hawaii's volcanoes are due to an oceanic hotspot) If there is gas in
the lava it will "fizz" out in spectacular lava fountains.
A'a Pahoehoe - ANSWER Temperature can also play a role in lava bahavior. A'A has a
jagged pointy crumbly texture. They move fast and cool quickly.
,Pillow Basalts, Vesicular Basalts, Lava tubes and caves - ANSWER Pillow Basalts: Form
specifically where basalt lava flows into water.
Vesicular Basalts: Has bubbles in it, where gas was trapped in the cooling lava.
Lava tubes: Basalt can form lava tubes, when the surface of the flow cools, but lava
continues flowing underneath.
Caves: When the tube drains, a lava cave is formed.
Explosive eruptions - ANSWER Eruption column: Up to 25 miles high. 2-200 cubic miles
of material ejected. 100,000 tons per second. Andesitic and rhyolitic are high in silicate
and high viscosity. They erupt extremely loudly and unpredictably. Andesitic volcanoes
tend to occur where subduction is occurring, and form volcanic arcs.
The andesite line - ANSWER Partial melting of basalt occurs about 80 km deep, and 250
km beyond the surface subduction zone. In the Pacific, this explains the andesite line.
Pumice - ANSWER Because andesitic and rhyolitic magmas are thicker, gases can't
escape as easily, so the rocks that are formed can have more bubbles than basalt. This
is called pumice.
Calderas - ANSWER Creation of a caldera: Crater Lake, Oregon. Crater Lake is North
America's deepest lake. It is 1950 feet deep at its deepest, and roughly five by six miles
in area.
Types of volcano by shape - ANSWER 1.Cinder cones: Small, basalt lava flow spills out
from base of cinder cone, porous, doesn't come out of the top of the cinder cone, it
flows out through holes at the base.
2.Shield Volcano: Gently sloping dome built of thousands of highly fluid )low viscosity)
basaltic lava flows. Ex: Hawaiian islands. Mauna Loa and Tamu Massif.
3.Stratovolcano/Composite: Combination of a cinder cones and shield volcano. They are
mountain-sized, steeply-sided volcanoes composed of alternating layers of pyroclastic
material and sticky, viscous lava flows.
Related to how thick or sticky your magma is.
, Large igneous provinces - ANSWER Extremely large areas of basalt volcanism. Deccan
Traps: 6500 feet thick, 193,000 square miles. (About the size of Spain)
Volcanic hazards - ANSWER Lava flows can destroy things.
Will eject pyroclasts and glassy ash.
Long term damage caused by tephra(Tiny mineral particles)
Up to 450 mph and 1000 degrees C.
Sometimes poisonous gases can be released without and eruption, such as in the case
of Lake Nyos, Cameroon, in 1986.
Can cause landslides or lahars.
Can cause earthquakes and tsunamis.
Elastic Rebound Theory - ANSWER Harry Fielding Reid used Lawson's observations to
develop the elastic rebound theory.
In geology, the elastic-rebound theory is an explanation for how energy is released
during an earthquake.
As adjoining plates on the Earth's surface move in opposite directions, the rocks which
span the opposing sides of the incipient fault are subjected to extreme shear stress.
Slowly they deform, until their internal rigidity is exceeded. Then they separate with a
rupture along the fault line; the sudden movement releases accumulated energy, and
the rocks snap back almost to their original shape. The previously solid mass is divided
between the two slowly moving plates, the energy released through the surroundings in
a seismic wave.
Faults, Epicenter, and Focus - ANSWER Faults: Some faults are small. Some like the San
Andreas fault are 1400 km long and experience earthquakes in the top 15 km. There are
three types of faults.
1.Reverse/Thrust: Most powerful earthquakes, and can be shallow or deep. Happen in
convergence zones where subducting under continental plate.(Megathrust
earthquakes)
2. Strike-slip: Medium in energy, and usually shallow. Happen in transform zones.
3. Normal: Lower in energy, mostly occur in oceans. Happen in divergence zones.
VERIFIED!!
What is a volcano? - ANSWER A volcano is a vent in the Earth's crust through which
magma, ash, and gases erupt.
Where do volcanoes occur? - ANSWER Volcanoes occur at divergent plate boundaries
where convective magma is rising to the surface, at convergent boundaries where
subducting crust is being partially melted, and at smaller hot spots. (Most volcanoes are
at the bottom of the sea)
What comes out of a volcano? - ANSWER Lava, rocks, and gases.
Effects of volcanic gas - ANSWER Volcanic carbon dioxide and chemical weathering are
the main controls on Earth's long-term (millions of years) climate. Volcanoes also emit
considerable amounts of sulfur dioxide. Sulfur also forms aerosols, which can cause
short-term(months to years) changes in climate.
Silicate in magmas - ANSWER Magma is composed almost entirely of metal silicate
minerals. Magma also contains 0.2%-3% dissolved gases, mostly water and carbon
dioxide. More silicate means higher viscosity. Because of this, basaltic magmas and
volcanoes will be distinctly different from andesitic and rhyolitic magmas and
volcanoes. Ocean hotspots and divergent boundaries produce basalt magmas, which
will be thin and runny. Continent hotspots and subduction zones will produce andesitic
and rhyolitic magmas, which will be thick and sticky.
Hawaiian Eruptions - ANSWER Low viscosity, basaltic magma causes non-explosive or
Hawaiian eruptions. (Hawaii's volcanoes are due to an oceanic hotspot) If there is gas in
the lava it will "fizz" out in spectacular lava fountains.
A'a Pahoehoe - ANSWER Temperature can also play a role in lava bahavior. A'A has a
jagged pointy crumbly texture. They move fast and cool quickly.
,Pillow Basalts, Vesicular Basalts, Lava tubes and caves - ANSWER Pillow Basalts: Form
specifically where basalt lava flows into water.
Vesicular Basalts: Has bubbles in it, where gas was trapped in the cooling lava.
Lava tubes: Basalt can form lava tubes, when the surface of the flow cools, but lava
continues flowing underneath.
Caves: When the tube drains, a lava cave is formed.
Explosive eruptions - ANSWER Eruption column: Up to 25 miles high. 2-200 cubic miles
of material ejected. 100,000 tons per second. Andesitic and rhyolitic are high in silicate
and high viscosity. They erupt extremely loudly and unpredictably. Andesitic volcanoes
tend to occur where subduction is occurring, and form volcanic arcs.
The andesite line - ANSWER Partial melting of basalt occurs about 80 km deep, and 250
km beyond the surface subduction zone. In the Pacific, this explains the andesite line.
Pumice - ANSWER Because andesitic and rhyolitic magmas are thicker, gases can't
escape as easily, so the rocks that are formed can have more bubbles than basalt. This
is called pumice.
Calderas - ANSWER Creation of a caldera: Crater Lake, Oregon. Crater Lake is North
America's deepest lake. It is 1950 feet deep at its deepest, and roughly five by six miles
in area.
Types of volcano by shape - ANSWER 1.Cinder cones: Small, basalt lava flow spills out
from base of cinder cone, porous, doesn't come out of the top of the cinder cone, it
flows out through holes at the base.
2.Shield Volcano: Gently sloping dome built of thousands of highly fluid )low viscosity)
basaltic lava flows. Ex: Hawaiian islands. Mauna Loa and Tamu Massif.
3.Stratovolcano/Composite: Combination of a cinder cones and shield volcano. They are
mountain-sized, steeply-sided volcanoes composed of alternating layers of pyroclastic
material and sticky, viscous lava flows.
Related to how thick or sticky your magma is.
, Large igneous provinces - ANSWER Extremely large areas of basalt volcanism. Deccan
Traps: 6500 feet thick, 193,000 square miles. (About the size of Spain)
Volcanic hazards - ANSWER Lava flows can destroy things.
Will eject pyroclasts and glassy ash.
Long term damage caused by tephra(Tiny mineral particles)
Up to 450 mph and 1000 degrees C.
Sometimes poisonous gases can be released without and eruption, such as in the case
of Lake Nyos, Cameroon, in 1986.
Can cause landslides or lahars.
Can cause earthquakes and tsunamis.
Elastic Rebound Theory - ANSWER Harry Fielding Reid used Lawson's observations to
develop the elastic rebound theory.
In geology, the elastic-rebound theory is an explanation for how energy is released
during an earthquake.
As adjoining plates on the Earth's surface move in opposite directions, the rocks which
span the opposing sides of the incipient fault are subjected to extreme shear stress.
Slowly they deform, until their internal rigidity is exceeded. Then they separate with a
rupture along the fault line; the sudden movement releases accumulated energy, and
the rocks snap back almost to their original shape. The previously solid mass is divided
between the two slowly moving plates, the energy released through the surroundings in
a seismic wave.
Faults, Epicenter, and Focus - ANSWER Faults: Some faults are small. Some like the San
Andreas fault are 1400 km long and experience earthquakes in the top 15 km. There are
three types of faults.
1.Reverse/Thrust: Most powerful earthquakes, and can be shallow or deep. Happen in
convergence zones where subducting under continental plate.(Megathrust
earthquakes)
2. Strike-slip: Medium in energy, and usually shallow. Happen in transform zones.
3. Normal: Lower in energy, mostly occur in oceans. Happen in divergence zones.
