Volcanoes

The Volcanic Setting

Subduction zonesRift valleysHot spots

Effusive• gentle flows• lots of lava

Explosive • viscous lava• trapped gases

shield volcanoes cinder cones plateau basalts

composite volcanoescalderas

Type of Eruption Landforms

Cinder coneBig Cinder Butte, Craters of the Moon, Idaho

- forms small hills, less than 450 m high

- black scoria rock with air bubbles

Shield volcanoMauna Loa, Hawaii

•

Low viscosity magmaGases readily escape from this magma

Effusive eruptions

Kilauea, Hawaii

Hot spot

Seamounts

Plateau basalts

CONTINENTAL RIFT VALLEY

Photo of Rift ValleyIn East Africa

Composite volcano

Mount PinatuboJune, 1991

Shield/Composite Comparison

Mount St. Helens: the day before

Live Photo of Mt. St. Helenshttp://www.fs.fed.us/gpnf/volcanocams/msh/

Four years later

Flooding (from steam-melted ice and snow)

Carbon dioxide (CO2 : 250,000 ppm !)Hydrogen sulphide (H2S)Sulphur dioxide (SO2)Hydrofluoric acid (HF)Chlorine (Cl) compounds

Four years later

CalderaCrater Lake, Oregon

windblown ash landed in Calgary

6600 years ago

Volcanic hazards and effects• hot ash (pyroclastics)• steam and gas explosions• lava flows• poisonous gases

(sulfuric acid; even CO2 ifat 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-continentalplate collision.

The logarithmic scale of earthquake amplitude-magnitude measurement is called the _____ scale.

a) Mercalli

b) tectonic activity

c) Richter

d) Beaufort

e) Fujita

The logarithmic scale of earthquake amplitude-magnitude 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) Kīlaeua, 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) Kīlaeua, HI

c) Mount St. Helens, WA

d) Mount Mayon, Philippines

e) Mount Pinatubo, Philippines