Geos Homework 3

Moderately viscous and gas-rich ____________ lavas can erupt as lava flows or pyroclastic materials, leading to the steepening slope of composite volcanoes.

andesitic

pore water pressure

groundwater extraction wastewater injection

Which phenomenon can explain the presence of volcanoes in the middle of the Pacific Ocean?

hot spots

In general, where do volcanoes form in subduction zones?

on the overriding plate, away form the convergent boundary

Which of the following objects has a size similar to that of lapilli?

A marble (15 mm)

Crustal rifting is currently occurring in East Africa. Which of the following features would you expect to find there?

All of the above are correct

Which of the following mountain ranges are examples of continental arcs?

Andes and Cascades

Which of the following is a layer of the Earth that is classified NOT by composition, but by physical properties?

Asthenosphere

convergent boundary

Most earthquakes in mountains or near mountains are associated with this kind of boundary. Most earthquakes near coastlines occur along this kind of boundary. Most earthquakes occur along this kind of boundary.

Divergent boundary

Most earthquakes in the middle of the oceans occur along this kind of boundary.

What is the main material being subducted at an ocean-continent convergent boundary?

Oceanic lithosphere

Why are volcanic chains associated with convergent boundaries?

Partial melting occurs due to subduction.

How do plates move at convergent plate boundaries?

Plates move toward one another.

What are two differences between oceanic crust and continental crust?

The continental crust is thicker and less dense than oceanic crust.

At a subduction zone where oceanic lithosphere meets continental lithosphere, which would subduct and why?

The oceanic lithosphere would subduct because it has a higher density at 3.0 grams per cubic centimeter.

Why are volcanoes NOT found at transform boundaries?

Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.

Which of Hawaii's five volcanoes are still considered to be active?

Kilauea Mauna Loa

How is the thickness of the lithosphere going to change as it moves away from a divergent plate boundary?

Lithosphere will thicken as more mantle is added.

Why are volcanoes not found at transform boundaries?

Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.

Divergent boundaries are not one, smooth ridge of separation. Instead, they are broken into a series of segments, with different segments of fault offset from others. What features allow for the offset of divergent boundaries?

Transform faults

cinder cones

Volcano known for reddish-brown lapilli Volcano with a crater at the summit and steep flanks

The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?

an ocean

Where are tectonic plates located?

at Earth's surface

Plates move apart at __________ boundaries, move together at __________ boundaries, and move side-by-side at __________ boundaries.

divergent/convergent/transform

Complete this statement: Divergence is to moving away as convergence is to _______.

moving toward

Oceanic lithosphere contains oceanic crust and the __________.

outermost part of mantle beneath the oceanic crust

How do plates move at divergent plate boundaries?

plates move apart

How do plates move at transform plate boundaries?

plates move side by side

How do plates move at convergent plate boundaries?

plates move together

Explosive eruptions of ______________ create steep-sided cinder cone volcanoes.

pyroclastic materials

The volcanic islands in the above figure were created as the tectonic plate passed over a hot spot in the mantle. Based on the ages of the volcanic islands, in what direction was the tectonic plate moving toward?

toward the west

Which plate boundary is NOT associated with volcanic eruptions?

transforms

Which of the following statements about earthquakes with magnitude greater than 4.0 is most accurate?

Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with plate boundaries.

What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?

The Earth would increase in volume.

Which type of plate boundary is most closely associated with uplifting continental regions and mountain building?

convergent boundaries

In general, where do earthquakes AND volcanic eruptions occur?

convergent plate boundaries divergent plate boundaries

What are the three types of plate boundaries?

divergent, convergent, and transform

crust

is Earth's stiff, rigid, rocky shell part of this layer has a relatively homogeneous composition, while the other part is less uniform in composition

core

contains iron and nickel contains a liquid outer layer and a solid inner layer

Isostatic adjustment

dam construction mining

The S wave arrives 3 minutes after the P wave, so the epicenter is approximately ____________ away.

1250 miles

The S wave arrives 1 minute after the P wave, so the epicenter is approximately _______ away.

250 miles

The S wave arrives 5.5 minutes after the P wave, so the epicenter is approximately ____________ away.

2500 miles

In a collision between two continental plates, can a continental plate subduct? Why or why not?

Continental plates are too buoyant to subduct.

Which type of tectonic boundary is the result of two tectonic plates colliding with each other?

Convergent boundary

mantle

contains a weak layer below the lithosphere contains rock rich in magnesium and iron.

Which of the following has the single most immediate effect on lava's ability to solidify?

temperature

Which tectonic boundary results when two tectonic plates pull apart from each other?

Divergent boundaries

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.

Volcanic ash is best described as which of the following?

Microscopic pieces of rock ejected by a volcano

Plate A has oceanic lithosphere on its leading edge that is 10 million years old. Plate B has oceanic lithosphere on its leading edge that is 200 million years old. Which plate will be subducted if they collide with each other, and why?

Plate B will subduct because it is older—and therefore colder—and more dense.

How do plates move at divergent plate boundaries?

Plates move apart.

How do plates move at transform plate boundaries?

Plates slide past one another.

What is the relationship between the crust and lithosphere?

The crust is part of the lithosphere.

A very steep-sided volcano built primarily from ejected lava fragments is called a ___________.

cinder cone

Composite cone

Volcano with a steep summit and broad, moderately steep flanks Volcano known for erupting lava and pyroclastic material

shield volcano

Volcano with very broad slopes and a caldera Volcano known for long lava flows and lava tubes

Which of the following is the volcanic feature in which magma rises through before it is released at the surface?

conduit

What is a volcanic arc?

a row of volcanoes that forms on the overriding plate near a subduction zone

Where is the youngest ocean floor found?

along the crest of mid-ocean ridges

A __________________ has broad and moderately steep flanks and a steep summit. It results from the eruption of a mixture of both lava flows and pyroclastic deposits that contain less fluid materials and travel shorter distances.

composite volcano

Mexico City

approximately 4 minutes

New York City

approximately 5 minutes

Nome

approximately 6 minutes

In general, where do both earthquakes and volcanic eruptions occur? Choose all that apply.

at divergent plate boundaries at convergent plate boundaries

Broad sheets of fluid ____________ lava travel long distances and give shield volcanoes their distinctive shape.

basaltic

Which of the following volcanic materials flows out of a volcanic vent?

lava

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?

magnesium iron

Which geologic features are associated with divergent boundaries?

mid-ocean ridges and continental rift valleys

What forms at divergent plate boundaries?

new oceanic lithosphere

Which geologic features are associated with convergent boundaries?

ocean trenches and volcanoes

A wide volcano that produces mainly basaltic lava flows is called a _____________.

shield volcano