Volcanoes
Volcanoes
The Volcanic Setting
Subduction zones
Rift valleys
Hot spots
Type of Eruption
Effusive
• gentle flows
• lots of lava
Explosive
• viscous lava
• trapped gases
Landforms
shield volcanoes cinder cones plateau basalts composite volcanoes calderas
Cinder cone
Big Cinder Butte,
Craters of the Moon, Idaho
- forms small hills, less than 450 m high
- black scoria rock with air bubbles
Shield volcano
Mauna Loa, Hawaii
•
Low viscosity magma
Gases readily escape from this magma
Effusive eruptions
Kilauea, Hawaii
Seamounts
Hot spot
Plateau basalts
CONTINENTAL
RIFT VALLEY
Photo of Rift Valley
In East Africa
Composite volcano
Mount Pinatubo
June, 1991
Shield/Composite Comparison
Mount St. Helens: the day before
Four years later
Live Photo of Mt. St. Helens http://www.fs.fed.us/gpnf/volcanocams/msh/
Flooding (from steam-melted ice and snow)
Carbon dioxide
(CO
2
: 250,000 ppm !)
Hydrogen sulphide (H
Sulphur dioxide (SO
2
)
Hydrofluoric acid (HF)
2
S)
Chlorine (Cl) compounds
Four years later
Caldera
Crater Lake, Oregon
6600 years ago windblown ash landed in Calgary
Volcanic hazards and effects
• hot ash (pyroclastics)
• steam and gas explosions
• lava flows
• poisonous gases
(sulfuric acid; even CO
2 if at extreme concentrations)
• landslides
• tree blowdowns
• lahars (steam-melted ice and snow cause flooding and large mudflows)
• increase in atmospheric dust
(decreased global temperatures in short term – increase in long term?)
Volcanic Benefits
New fertile soils
- Hawaii, Philippines
Geothermal energy
- Iceland, Italy, New Zealand
New real estate
- Iceland, Japan, Hawaii
Diamond-bearing Kimberlite Pipe
A terrane is a a) region where a craton is exposed at the surface.
b) migrating crustal piece that becomes attached to plates.
c) nucleus or heartland region of continental crust.
d) chain of islands formed from hotspot volcanism.
e) downward-faulted block of crust.
A terrane is a a) region where a craton is exposed at the surface.
b) migrating crustal piece that becomes attached to plates.
c) nucleus or heartland region of continental crust.
d) chain of islands formed from hotspot volcanism.
e) downward-faulted block of crust.
The deformation of rocks by compression, such as that occurring at convergent plate boundaries, is called _____.
a) thrusting b) faulting c) lithification d) shearing e) folding
The deformation of rocks by compression, such as that occurring at convergent plate boundaries, is called _____.
a) thrusting b) faulting c) lithification d) shearing e) folding
An anticline is the result of which type of crustal stress?
a) isostasy b) tension c) shear d) subduction e) compression
An anticline is the result of which type of crustal stress?
a) isostasy b) tension c) shear d) subduction e) compression
The Basin and Range Province of the United States consists of alternating horsts and grabens due to the presence of numerous _____ faults.
a) right-lateral b) left-lateral c) reverse d) thrust e) normal
The Basin and Range Province of the United States consists of alternating horsts and grabens due to the presence of numerous _____ faults.
a) right-lateral b) left-lateral c) reverse d) thrust e) normal
A non-volcanic mountain range is likely an expression of a(an) a) oceanic plate-oceanic plate collision.
b) oceanic plate-continental plate collision.
c) oceanic plate-oceanic plate divergence.
d) continental plate-continental plate divergence.
e) continental plate-continental plate collision.
A non-volcanic mountain range is likely an expression of a(an) a) oceanic plate-oceanic plate collision.
b) oceanic plate-continental plate collision.
c) oceanic plate-oceanic plate divergence.
d) continental plate-continental plate divergence.
e) continental plate-continental plate collision.
The logarithmic scale of earthquake amplitudemagnitude measurement is called the _____ scale.
a) Mercalli b) tectonic activity c) Richter d) Beaufort e) Fujita
The logarithmic scale of earthquake amplitudemagnitude measurement is called the _____ scale.
a) Mercalli b) tectonic activity c) Richter d) Beaufort e) Fujita
The epicenter of an earthquake is defined as a) the area at the surface that is directly above the focus.
b) the subsurface area where the motion of the seismic wave was initiated.
c) the sticking point along a fault that prevents movement.
d) an area that is tectonically quiet and overdue for an earthquake.
e) the area of greatest structural damage and loss of life.
The epicenter of an earthquake is defined as a) the area at the surface that is directly above the focus.
b) the subsurface area where the motion of the seismic wave was initiated.
c) the sticking point along a fault that prevents movement.
d) an area that is tectonically quiet and overdue for an earthquake.
e) the area of greatest structural damage and loss of life.
Composite volcanoes a) are effusively formed mountains.
b) are associated with flood basalts.
c) typically erupt from the ocean floor.
d) have gently sloping sides.
e) are explosively formed mountains.
Composite volcanoes a) are effusively formed mountains.
b) are associated with flood basalts.
c) typically erupt from the ocean floor.
d) have gently sloping sides.
e) are explosively formed mountains.
All of the following are specific examples of explosive eruptions except _____.
a) White Island, New Zealand b) K īlaeua, HI c) Mount St. Helens, WA d) Mount Mayon, Philippines e) Mount Pinatubo, Philippines
All of the following are specific examples of explosive eruptions except _____.
a) White Island, New Zealand b) K īlaeua, HI c) Mount St. Helens, WA d) Mount Mayon, Philippines e) Mount Pinatubo, Philippines
