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Geo CH. 5 ?'s
Terms in this set (60)
Which of the following increases viscosity of magma?
an increase in silica content
What layers make up a composite volcano, such as Mt. Rainier?
Cinders, ash, and lava flows
-Volcano fed by silica-rich magma
-Volcano fed by high-temperature (1000∘C) magma
-Volcano fed by mafic (basaltic) magma
-Volcano fed by magma with low amounts of dissolved gases
Not related to eruption explosiveness
-Volcano at high elevation (>10,000 feet above sea level)
-Volcano that has not erupted for a long time
Upper Lithosphere / Crust
-Magma with greatest silica content
-Magma undergoing degassing during an eruption
-Magma with density equal to or less than the crust
-Magma undergoing partial crystallization of high-density minerals
-Magma with density less than the lower lithosphere but higher than the crust
Magma with the highest temperature
-fast lava flow
-90% of lava on Earth
-flows in sheets
-intermediate lava flow
-slow lava flow
-1% of lava on Earth
-has a rough, broken surface. It is caused by rapidly moving basalt that cools quickly.
-has a smooth, billowy surface. It is caused by slowly moving basalt that is still hot.
-results from a relatively fluid lava cooling and forming an outer shell. The lava continues to flow inside the outer shell.
-has a rough surface composed of smooth-sided fragments. It is formed by viscous lava cooling quickly.
-is composed of solid, bubble-like masses. It is caused by extremely quick lava quenching.
Which of the following characterizes a typical eruption of Kilauea Volcano in Hawaii?
quiet outpourings of fluid lavas
Why does a volcano fed by highly viscous magma pose the greatest threat to life and property?
because potential eruptions are highly explosive and less predictable
What term describes lava that has rough, jagged surfaces with sharp edges?
The average composition of rocks comprising a large composite cone or stratovolcano is similar to a(n) ________ magma.
Which of the following statements is true of composite volcanoes?
They erupt silica-rich lavas that cool to andesite or rhyolite.
Which volcanic landform is created by the collapse of the summit of a volcano?
________ magma is the most abundant type of erupted at oceanic spreading centers.
Which volcanic hazard occurs when melted snow or excessive rain mixes with volcanic sediments?
Which type of volcanic hazard results in a very fast-moving cloud of super-heated ash and toxic gases?
What type of volcanism is associated with the zone of active volcanoes called the Ring of Fire?
convergent plate boundary volcanism
The Columbia Plateau in Washington and Oregon is ________.
a flood basalt plateau
A _____ is formed on the volcano summit by explosive eruptions and is composed of accumulated volcanic debris.
Depletion of the upper part of a magma chamber during a volcanic eruption can result in gravitational collapse of the volcanic summit to form a __________.
A ________ is an opening where volcanic materials erupt at the Earth's surface, and can form on the flanks of a larger volcano in the case of a _________.
The pipelike feature through which magma travels upward from an underground magma chamber is called a ________.
A ________ results when magma collects or ponds due to its density being higher than that of overlaying materials.
Which of the following objects has a size similar to that of lapilli?
A marble (15 mm)
Volcanic ash is best described as which of the following?
Microscopic pieces of rock ejected by a volcano
Which of the following volcanic materials flows out of a volcanic vent?
Which of the following is the volcanic feature in which magma rises through before it is released at the surface?
The Afar region is one of the most environmentally challenging areas on the planet. The geopolitics of Afar are equally challenging. Why?
Ethiopia is controlled by a dictator who demands payment from any tourists in the Afar region.
What does the volcano's name, Erta Ale, mean in the local Afar language?
What makes Erta Ale so unique among other active volcanoes in the world?
It is one of only a few volcanoes that have permanent lakes of molten lava in their craters.
Which of the following accurately describes the motion of lava in Erta Ale's crater?
The lava wells up on one side of the crater and forms a dark crust. As the crust cools, it flows across the lake driven by the churning lava below. Once it flows across the lake, the crust sinks down and the process begins again.
The distinctive lava flow pattern in Erta Ale's crater is important because it is similar to the processes occurring deep inside the earth. The repetitive process whereby magma rises from the mantle, cools and solidifies, and then sinks and liquefies is called __________.
a convection current
Which of the following scenarios best describes how the Hawaiian Islands formed in the Pacific Ocean?
Magma generated from a hot spot burned through the overlying plate to create volcanoes.
Which materials in Hawaii's lava help to keep it fluid for longer at the surface (as opposed to cooling and solidifying quickly), thus allowing extensive lava flows to develop?
Which of Hawaii's five volcanoes are still considered to be active?
Which of the following has the single most immediate effect on lava's ability to solidify?
What geologic process is related to caldera formation?
How do calderas form?
Calderas form when the summit of a volcano collapses.
Where is Crater Lake?
In addition to rock deposits, what evidence do we have that the eruption that preceded the formation of Crater Lake was very large?
The eruption was so large that the magma chamber under Crater Lake partially emptied, causing the volcano to become unstable and collapse.
Why does Crater Lake have an island in it?
The volcano is still active, and a new volcanic peak has formed.
Of the three lava compositions, which would be the hottest?
Of the three lava compositions, which would be the coolest?
The viscosity of magma increases with:
high % silica and cooler temperatures.
Based on the combination of silica content and temperature, mafic magmas will have a(n) __________ viscosity.
Based on the combination of silica content and temperature, intermediate magmas will have a(n) _________ viscosity.
Based on the combination of silica content and temperatures, felsic magmas will have a(n) ___________ viscosity.
The viscosity of magma helps determine if it will erupt explosively or effusively (quiescently). A thicker lava is better at trapping bubbles of gas as they come out of solution. Using information from the readings, which of the following magma compositions is likely to trap more bubbles, and lead to an explosive eruption?
Plutonic rocks are formed when magma cools deep in the crust, without erupting. Magma that is very thick (viscous) is more likely to remain below the surface. Based on information in the readings, which of the following magma is most viscous, and therefore likely to form plutonic rocks?
Pahoehoe flows are found closer to the vent because
the lava is hottest near the vent.
Shield cones form from
mafic lava because it is very fluid and spreads into thin sheets.
This set is often in folders with...
Geology 101 Ch. 1 ?'s
Geology 101 Terms Ch.1
Geo CH.2 ?'s
Geo 101 Ch.2 Terms
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