volcanos

9. What is Tephra/Pyroclastic material? How is Tephra/Pyroclastic material classified? List these clast sizes from smallest to largest size.

Tephra/Pyroclastic material refers to all hot, fragmental material that is ejected from a volcano after confining pressure over a volcano is rapidly reduced causing the magma and rock material to be shattered. Tephra/Pyroclastic material is classified based on the size of the pyroclasts, which range from dust to ash, to cinders, to lapilli, to bombs and blocks in size from smallest to largest.

10. Name 1 volcanic rock that is pyroclastic in origin and texture.

"Volcanic Tuff" of just "Tuff"

Geyser

- We did not discuss in class so do not need to know this one

19. What is a Cinder Cone? List 1 example.

A small, conical-shaped volcanic cone built entirely of loose pyroclastic material, mostly cinder in size. (examples include Capulin Volcano,Sunset Crater Volcano)

20. What is a Volcanic/Lava Dome, and what compositional type of lava are Volcanic/Lava Domes composed of?

A steep-sided mound that forms when viscous, doughy lava piles up near a volcanic vent. Domes are formed primarily by Rhyolitic lavas.

12. What is a Hot Spot?

A volcanic center, 100 to 200 km, across and persistent for at least a few tens of million of years, that is thought to be the surface expression of at persistent rising plume of hot mantle material. Hot spots are not linked to Island Arcs and may or may not be associated with Ocean Ridges.

15. Define, describe the predominant type of lava/volcanic materials erupted, list the tectonic setting, and give at least one example of each of the following types of volcanic cones/landforms.

A. Shield Cones Shield Cones are large, gently sloping volcanic cones composed entirely of basaltic lava flows. They form over Oceanic Hot Spots. Mauna Loa and Kilauea in Hawaii (all Hawaiian Volcanoes) and Sierra Grande in New Mexico are examples. B. Composite Cones or Stratovolcanoes Composite Cones or StratoVolcanoes are moderately large volcanic cones with moderately steep slopes composed of alternating layers of lava (andesitic and basaltic) and pyroclastic materials. They form over Subduction Zone-type Convergent Boundaries. Examples include: Mount Fuji,St. Helens, Mount Shasta, Mount Ranier, Vesuvius, Mayon, and Merapi. C. Calderas Large steep-walled depressions formed by collapse after huge outpouring of large volume of magma source. The dominant composition of material associated with culminating eruptions that result in calderas is Rhyolite. The most explosive of Earth's volcanoes. Examples include: Yellowstone Lake in Wyoming, Valle Grande/Valles Caldera in New Mexico, Lake Toba in Sumatra, and Hakone in japan

17. Briefly describe how a caldera forms, and list 2 examples of calderas.

Calderas form after a massive eruption of primarily pyroclastic material from a composite cone. After enormous amounts of magma have been emptied as a result of the eruption, most of the summit of the Composite Cone collapses, leaving a huge, somewhat circular, steep-walled depression or caldera

2. Along which type(s) of plate boundaries does volcanism occur?

Divergent and Convergent (Subduction Zone-type)

21. Briefly define: Volcanic Crater -

Funnel-shaped depression, usually at the summit of a volcano, produced by explosive eruptions from the Vent.

3. Compare and contrast Magma and Lava.

Magma is a viscous liquid or molten rock below the Earth's surface with some suspended crystals and dissolved gases. Lava is magma that has erupted onto the Earth's surface.

11. Compare and contrast the composition of magma (i.e., magma type) at Subduction Zone-type Convergent Boundaries versus Mid-ocean Ridges at Divergent Boundaries.

The composition of magma generated at Subduction Zones is predominantly Andesitic, but can be Rhyolitic at Continental-type Subduction Zones whereas the composition of magma formed at Mid-ocean Ridges and Rises is always Basaltic in composition.

16. What compositional type of lava is erupted from Mid-ocean Ridges and Rises? List 2 examples of oceanic ridges or rises.

The compositional type of lava erupted from Mid-ocean Ridges and Rises is always Basalt. Examples include: the Mid-Atlantic Ridge, the East Pacific Rise, and the Indian Ridge.

4. Define Viscosity.

Viscosity is the Internal Resistance to Flow in Liquids

Fumarole/Solfatara -

Volcanic Vent which emits gases; craters of many dormant volcanoes contain fumaroles. Fumaroles are also called, "Solfataras".

14. How are Volcanoes and Volcanic Landforms classified?

Volcanoes are classified based on their size and shape (morphology) and their Tectonic Setting.

6. What are the 3most abundant gases erupted from volcanoes?

Water Vapor (H2O) and Carbon Dioxide (CO2) and Sulfur Dioxide (SO2)

7. What property of a magma controls the ease with which gases can escape from it?

viscosity

1. What is a volcano?

A Volcano is a vent in the surface of the Earth through which magma and associated gases and pyroclastic material erupt and the conically-shaped landform that is produced by ejected material.

8. Compare and contrast pahoehoe and aa lava flows.

Pahoehoe lava flows are generally basaltic in composition and have a smooth, ropy texture whereas Aa lava flows are also generally basaltic in composition and have a jagged, angular, blocky texture.

5. Compare and contrast the 3 compositional types of magma, basaltic, andesitic, and rhyolitic, in terms of composition (especially the silica content), viscosity, and temperature.

RHYOLITIC - High SiO2, High Na, K, Al, Low Fe, Mg, Ca, High Viscosity, Low Temperature ANDESITIC - Intermediate Silica and other components, Viscosity, and Temperature BASALTIC - Low SiO2, High Fe, Mg, Ca, Low Na, K, Al, Low Viscosity, High Temperature