Assignment 6 - Volcanoes
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El Paso Community College *
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Course
1301
Subject
Geology
Date
Dec 6, 2023
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docx
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Uploaded by jessikadenn28
Assignment 6 - Volcanoes
1-
Compare and contrast the following: shield volcanoes, composite
cones/stratovolcanoes, and cinder cones.
Shield volcanoes:
o
Largest volcanoes
o
Broad, slightly dome-shaped.
o
Basaltic lava
o
Most begin on the ocean floor (called seamounts)
Composite cones/ stratovolcanoes:
o
Large, classic-shaped volcano
o
Composed of interbedded lava flows
o
Violent
eruptions
o
Most are located adjacent to the Pacific Ocean (e.g., Fujiyama, Mount St.
Helens)
Cinder cones:
o
Built from ejected basaltic lava (mainly cinder-sized) fragments, forming
a steep slope.
o
Small size and frequently occur in groups.
Shield volcanoes have a broad, low-profile shape with non-explosive basaltic eruptions, while
composite cones have a tall, steep shape with more explosive eruptions and a variety of lava
types. Cinder cones are the smallest, have a conical shape, and feature explosive eruptions with
fragmented lava. These differences are mainly due to variations in magma viscosity and
eruption dynamics.
2-
Compare and contrast the volcanoes of Alaska with the volcanoes of the Hawaiian
Islands
- Alaska: The volcanoes in Alaska are part of the Pacific Ring of Fire, a region
characterized by subduction zones, where one tectonic plate is forced beneath another.
Alaska has a variety of volcanic types, including stratovolcanoes (composite cones),
shield volcanoes, and cinder cones.
- The Hawaiian Islands: are situated in the middle of the Pacific Plate, away from plate
boundaries. They are the result of a hotspot, where a stationary plume of magma rises
from deep within the Earth's mantle, creating a series of shield volcanoes. The Hawaiian
Islands are primarily characterized by shield volcanoes, which are low, broad, and gently
sloping.
3-
Explain the similarities and differences between the melting taking place at the mid-
ocean ridge and at the subduction zone.
-
Similarities
Magma Formation: Both mid-
ocean ridges and subduction
zones involve the generation of
magma.
Plate Tectonics: Both processes
are closely related to the
movement of tectonic plates.
4-
Of the diagrams pictured below, which one represents a hot spot setting? How is such
setting evidence for plate tectonic theory, and name one location where such a setting
can be found.
- Diagram D represents the setting of a tectonic hotspot. This is the location like, where
an exceptionally hot and buoyant part of mantle exists beneath the surface, known as
hotspot mantle plume. Hawaiian Volcanic chain is the best example of a hotspot.
Yellowstone Park Volcano is also a hotspot setting.
Difference
Magma formation: at mid-ocean ridges
occurs at divergent plate boundaries, where
two tectonic plates are moving apart.
Plate tectonics: the melting at subduction
zones often leads to the formation of
volcanic arcs and trenches. It is associated
with the subduction of oceanic plates and
the formation of volcanic island arcs or
continental volcanic arcs.
5-
Where do you expect volcanoes to happen in North America and Why?
Pacific Ring of Fire: The Pacific Ring of Fire is the result of the subduction of the Pacific
Plate beneath the North American Plate. This subduction process leads to the
formation of stratovolcanoes and volcanic arcs.
Alaska: Alaska is situated along the Pacific Ring of Fire and features volcanoes resulting
from the subduction of the Pacific Plate beneath the North American Plate. These
volcanoes include stratovolcanoes and shield volcanoes.
Hawaiian Islands: The Hawaiian Islands are the result of a hotspot, where a stationary
plume of magma rises from the mantle to create a series of shield volcanoes. As the
Pacific Plate moves over this hotspot, it generates a chain of volcanic islands.
Yellowstone National Park: The Hawaiian Islands are the result of a hotspot, where a
stationary plume of magma rises from the mantle to create a series of shield
volcanoes. As the Pacific Plate moves over this hotspot, it generates a chain of volcanic
islands.
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