Question 1

If a volcanic eruption releases large amounts of aerosols into the atmosphere, they will reflect sunlight back to space and will cause a warming effect on Earth's climate for months or years.

Accepted Answer

The release of aerosols into the atmosphere from a volcanic eruption can actually have a cooling effect on Earth's climate for months or years because they reflect sunlight back to space and block some of it from reaching the Earth's surface.

Question 2

If large concentrations of sulfur dioxide molecules are released during volcanic eruptions like Pinatubu of 1991, this can reflect sunlight in the upper atmosphere and cause atmospheric cooling for Earth's climate.

Accepted Answer

Sulfur dioxide molecules can react with water vapor and form sulfuric acid aerosols, which reflect sunlight, causing cooling in the upper atmosphere. This can have a temporary cooling effect on Earth's climate.

Question 3

A sill igneous intrusion forms when magma is injected into a fracture that cuts across rock layers.

Accepted Answer

A sill is a type of igneous intrusion that forms when magma is injected horizontally into a fracture that cuts across rock layers. This results in a parallel layer of igneous rock that is often visible along the surface of a hill or mountain.

Question 4

Mount Vesuvius is an example of a ____ volcano that is a steep-sided volcano formed by an alternating series of lava flows and pyroclastic deposits and marked by repeated eruption.

Accepted Answer

Mount Vesuvius is a classic example of a stratovolcano, also known as a composite volcano. These volcanoes are characterized by steep sides, alternating layers of lava flows and pyroclastic deposits, and repeated explosive eruptions. Mount Vesuvius is also famous for its devastating eruption in AD 79 that buried the cities of Pompeii and Herculaneum.

Question 5

The eruption of Mount Helens in 1980 produced such great ash and sulfur clouds that Earth's surface temperatures were cooler for the following two years.

Accepted Answer

The eruption of Mount St. Helens in 1980 did produce significant ash clouds, but it did not have a notable long-term impact on Earth's climate or surface temperatures. The cooling effect on Earth's climate is more typically associated with larger volcanic eruptions like Mount Pinatubo in 1991.

Question 6

Volcanic ____ consist(s) of the smallest particles formed when liquid magma explodes into the air.

Accepted Answer

Ash consists of the smallest particles formed when liquid magma explodes into the air.

Question 7

If global warming reduced the amount of precipitation in the Yellowstone region, the confining pressure on superheated groundwater would decrease and may lead to more frequent hydrothermal explosions.

Accepted Answer

The decrease in precipitation would result in less confining pressure on the superheated groundwater, which could lead to more frequent hydrothermal explosions.

Question 8

Regional predictions based on the concentration of volcanoes in an area can be used to determine the intensity of a particular eruption because each eruption will contain the same type and volume of magma.

Accepted Answer

The concentration of volcanoes in an area may suggest the potential for volcanic activity in that region, but the intensity of a particular eruption cannot be accurately determined solely based on this factor. Each eruption can vary in terms of the type and volume of magma involved, as well as other factors such as the presence of gas and the type of volcanic eruption (e.g. explosive vs. effusive).

Question 9

____ explosions occur in regions in which the groundwater has been heated past the boiling point.

Accepted Answer

Hydrothermal explosions occur when heated groundwater reaches the boiling point, causing a sudden expansion and explosive release of steam and hot water. Pyroclastic explosions involve the ejection of fragments of magma and volcanic ash, air-fall tuff refers to deposits of volcanic material that have fallen from the air, and a caldera is a volcanic depression caused by the collapse of a volcano's summit.

Question 10

If you have two rocks and one contains small amounts of water, it will generally melt at a lower temperature than an otherwise identical dry rock.

Accepted Answer

This is because the water in the rock will absorb heat energy as it melts, which will slow down the heating of the rest of the rock until all of the water has melted. Once the water has melted, the temperature of the rock will begin to rise again. Therefore, the rock with water will have a lower melting temperature compared to the dry rock.

Question 11

The process of partial melting helped produce silica-rich continents because the source of the magma evolved from silica-poor mantle.

Accepted Answer

Partial melting of silica-poor mantle can produce magma with higher silica content, which can then form silica-rich continental crust through various geological processes.

Question 12

If you are looking at a volcano and its sides gently slope from the vent at angles between 6° and 12°, you are looking at a cinder cone volcano.

Accepted Answer

If the sides of a volcano gently slope at angles between 6° and 12°, it is most likely a shield volcano. Cinder cones are steep-sided and usually have angles between 30° and 40°.

Question 13

Yellowstone Park is an example of three overlapping ____.

Accepted Answer

Yellowstone Park is known for its geothermal activity and extensive hydrothermal systems, which are evidence of three overlapping calderas.

Question 14

Mauna Kea Volcano in Hawaii, measured from its true base at the bottom of the ocean, is the tallest mountain in the world and is classified as a shield volcano.

Accepted Answer

Mauna Kea volcano in Hawaii is measured from its true base at the bottom of the ocean and is the tallest mountain in the world, standing at 33,480 feet tall. It is classified as a shield volcano, which is a type of volcano that has gentle slopes, fluid lava flows, and is characterized by a wide, broad shape.

Question 15

Basaltic magma has longer chains of silicate tetrahedra than granitic magma allowing it to increase in velocity and this would cause basaltic volcanoes to erupt more violently than volcanoes with granite magma.

Accepted Answer

This statement is false. Basaltic magma has shorter chains of silicate tetrahedra than granitic magma, which allows it to flow more easily and results in less violent eruptions. Granite magma has longer chains of silicate tetrahedra and is more viscous, resulting in more explosive eruptions.

Question 16

A cinder cone volcanic eruption is typically active for only a short period of time because once the gas escapes, the driving force behind the eruption is removed unlike composite volcanoes which represent repetitive eruptions.

Accepted Answer

A cinder cone volcano erupts for a short period of time because the gas escapes quickly and the driving force behind the eruption is removed. In contrast, composite volcanoes may have repetitive eruptions over a longer period of time.

Question 17

Magma in the asthenosphere is primarily granite in composition because the magma is high in silica in the athenosphere.

Accepted Answer

Magma in the asthenosphere is primarily basaltic in composition, which is low in silica. Granite is formed from magma with higher levels of silica, but this typically forms in the continental crust, not the asthenosphere.

Question 18

The Columbia River plateau in the northwestern United States is an example of a(n) ____, in which lava covers the landscape like a flood.

Accepted Answer

The description of the landscape being covered in lava like a flood is characteristic of a flood basalt, which is a type of volcanic activity that covers vast areas with multiple layers of lava flows. Composite flow, ash-flow tuff, and welded tuff do not involve large-scale lava flows.

Question 19

If scientists can show that seismic waves rapidly slow down allowing S waves not to register beneath Mount Vesuvius, this means molten magma still exists at that depth and could erupt again in the future.

Accepted Answer

The answer of If scientists can show that seismic waves...

Question 20

Magma forms abundantly at transform boundaries because one plate is subducting into the mantle allowing for the formation of magma chambers.

Accepted Answer

Magma forms at divergent and convergent plate boundaries where there is volcanic activity, but not necessarily at transform boundaries where there is mainly horizontal movement of plates.

Quiz 8: Volcanoes and Plutons