Term
| The leading edge occurs on which side of a large lithospheric plate? |
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Definition
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| The trailing edge occurs on which side of a large lithospheric plate? |
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Definition
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Definition
| a long arc of volcanoes that lie on the leading edge of a lithospheric plate |
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Term
| Are there portions of an island arc located in California? If so, then where? |
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Definition
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Term
| What are the three prominent types of volcanoes? |
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Definition
| Shield, strato/composite, cinder |
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Term
| Strato volcanoes are composed of mixed layers of _______________ and __________ material. |
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Definition
| Pyroclast, solidified lava |
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Term
| How would you describe the composition of most stratovolcanoes? |
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Definition
| Mostly intermediate (andesitic) |
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Term
| Shield volcanoes are built up primarily from highly fluid, low viscosity ________ lava |
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Definition
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Term
| Where can you find a classic example of a shield volcano? |
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Definition
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Term
| What is the smallest type of volcano? |
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Definition
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Term
| What types of volcanoes are common is island arc settings? |
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Definition
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Term
| What is the average dip of subducting plates? |
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Definition
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Term
| If the dip of a plate is less than 45 degrees, then what happens to the distance between the locus of volcanic arc activity in the island arc and the trench? |
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Definition
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Term
| If the dip of the subducting plate is greater than 45 degrees, then what happens to the distance between the locus of volcanic activity and the trench? |
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Definition
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Term
| If water and other types of volatiles are introduced to the lower lithospheric mantle, then what happens? |
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Definition
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Term
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Definition
| the boundary between the mantle and crust |
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Term
| Geologist describe the accumulation of magma at the moho as... |
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Definition
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Term
| What are the chambers beneath volcanoes called? |
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Definition
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Term
| Hotspots are known to occur in: |
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Definition
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Term
| Relatively well known hotspots are located in: |
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Definition
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Term
| What would happen to the head of the plume if it rises to just a few kilometers beneath the sea bed or lad surface? |
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Definition
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Term
| Rifts are ____________ basins produced by the stretching or pulling apart of the crust. |
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Definition
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Term
| Which plates and microplats make up the east African Rift system? |
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Definition
| African plate, Arabian microplate, Somalian microplate |
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Term
| Is the east African rift system considered to be an old or young rift? |
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Definition
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Term
| What processes are associated with volcanism in the East African Rift system? |
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Definition
1. Magma effuses out of fissures to form flood basalts
2. Magma effuses out of central vents to form large shield volcanoes
3. magma explosively erupts to form large stratovolcanoes |
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Term
| What will eventually happen to the east african rift? |
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Definition
| It will subside into the indian ocean and be replaced by the midocean ridge |
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Term
| Viscosity is the internal resistance to ________ when a shear stress is applied. |
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Definition
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Term
| What happens to the viscosity as magma cools? |
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Definition
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Term
| What is the most viscous? Rhyolitic, basaltic, or andesitic magma? |
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Definition
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Term
| What is confining pressure? Does it increase or decrease with depth within the crust? |
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Definition
| Confining pressure: weight of overlying rock; it increases with depth |
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Term
| What does the term solubility refer to? |
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Definition
| It's ability to be dissolved in a liquid |
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Term
| What is meant by the phrase, "the volatile phase" |
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Definition
| the volatiles were separated from the solution |
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Term
| Under conditions where vapor pressure is the pressure produced by the volatile phase separating from the magma at a given temperature under equilibrium, the volatile phase separates from the magma is __________ the rate at which it is dissolved back into it. |
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Definition
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Term
| Exolution of the volatile phase will occur when the _________ _________ equals the __________ __________. |
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Definition
| Vapor pressure, confining pressure |
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Term
| If the exsolution of the volatile phase is a result of lowered confining pressure then it is called... |
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Definition
| First boiling (Isothermal decomposition) |
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Term
| If the exsolution of the volatile phase is brought on by the crystallization of anhydrous minerals like olivine, pyroxene, or the feldspars, then it is called... |
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Definition
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Term
| The process of exsolution of volatiles from a magma is called: |
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Definition
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Term
| If magma is degassed without an explosive eruption then it will effuse from the volcano as lava. This commonly occurs... |
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Definition
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Term
| Fragmentation surface forms when the volume of bubbles is about what percentage of the total volume of the magma column? |
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Definition
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Term
| The point source from which all material blasted out of the volcano is derived separates the exsolved magma below from the eruptive column above. What is the name for this surface? |
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Definition
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Term
| What is the eruption column? |
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Definition
| Region of hot gas and fragmented pyroclasts materials lying above the fragmentation surfaces |
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Term
| Tephra, and gases driven from the vent into the atmosphere through expansion make up the: |
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Definition
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Term
| What is the region where pyroclastic materials fall out of the eruption column, and the remaining mixture of tephra and gases becomes less dense than the surrounding atmosphere? |
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Definition
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Term
| Tephra that is pulled by gravity out of the eruption column commonly blankets the landscape is called: |
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Definition
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Term
| If the tephra is dominantly ash, then what is it called? If it is more lapilli sized tephra? |
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Definition
| Ash-fall Tuff, Ash-fall Lapillistone |
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Term
| Mixtures of hot gas, tephra, and rock fragments that form as the eruption column collapses or as a directed lateral blast are called __________ __________ . They also are sometimes referred to as _________ ___________. |
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Definition
| pyroclastic flow, nuees ardentes |
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Term
| The Volcanic Explosivity Index (VEI) is used to classify eruptions into 8 different varieties. What info is used to determine the VEI? |
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Definition
| Volume of material erupted, height of the eruption column, duration of eruption |
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Term
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Definition
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Term
| the VEI for a Hawaii type eruption is: |
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Definition
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Term
| Strombolian type eruption: |
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Definition
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Definition
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Term
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Definition
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Term
| Ultraplinian type eruption: |
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Definition
| 6-8 (strongest eruptions) |
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Term
| Hawaiian type eruptions typically involve highly _______ low ______________ basaltic lava. |
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Definition
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Term
| In what types of eruptions would you expect to see lava "fountaining" |
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Definition
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Term
| Which of the following types of eruptions typically involve andesitic to dacitic magma and result in explosive eruptions with columns reaching 5-10 km in height? |
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Definition
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Term
| What type of eruptions are characterized by large explosive events that form dark eruption columns of tephra and gas that extend into the stratosphere and can last from hours to days? |
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Definition
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Term
| Which of the following produces an eruption column that reaches 45 km or more into the atmosphere? |
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