Week 6 Assignment
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Sacramento City College *
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Course
300
Subject
Geology
Date
Dec 6, 2023
Type
docx
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4
Uploaded by EarlFreedom5294
Week 6 Assignment SCI 305
“Give it Some Thought” Questions Textbook pages 123-124:
Complete # 2 a-d
2)a. The first one A is Oceanic-oceanic convergent boundary. The second one B is Oceanic-continental convergent boundary. The last one C is Continental-
continental convergent boundary. b. Volcanic Island arcs develop on oceanic crust. Oceanic crust is denser than the continental crust, so it is subducted beneath the continental crust when the two plates collide. The subducting oceanic crust melts as it descends into the mantle, and the molten rock rises to the surface and forms volcanoes.
c.
Volcanoes are largely absent where two continental blocks collide because the two plates are too buoyant to be subducted. Instead, the two plates crumple and fold, forming a mountain range. The only volcanoes that may form in this setting are those that are associated with hot spots, which are areas of anomalously hot mantle that can rise to the surface and form volcanoes.
d.
Oceanic-oceanic convergent boundaries and oceanic-continental convergent boundaries differ in two main ways. The first being the type of crust that is subducted. In oceanic-oceanic convergent boundaries, the denser oceanic crust is subducted beneath the less dense oceanic crust. In oceanic-continental convergent boundaries, the denser oceanic crust is subducted beneath the less dense continental crust. The second being the type of volcanic activity that occurs.
In oceanic-oceanic convergent boundaries, the subducting oceanic crust melts to form andesitic magma, which rises to the surface and forms volcanoes. In oceanic-
continental convergent boundaries, the subducting oceanic crust melts to form andesitic magma, which rises to the surface and forms volcanoes. However, in oceanic-continental convergent boundaries, the andesitic magma can also mix with the continental crust, forming rhyolitic magma, which is more explosive.
“Give it Some Thought” Questions Textbook pages 157-158:
Complete #’s 3 a-d, 6 a-c
3) a. The P-Waves also known as Primary Waves reached the station first, because they were the fastest moving waves.
b.
The interval between the S-P waves is 6 minutes, as shown on the seismogram. The distance between two red parallel lines is 1 minutes, so distance between S-P = 6 minutes.
c.
As per the standard S-P interval to Epicenter distance, the distance of Epicenter for 6 minutes interval = 4,200 kms approximately.
d.
The Surface Waves shown on the right end of the seismogram have the highest amplitude. As we can see the height of wave undulations is highest, so it means the amplitude is highest.
6) a.
Segment 2 of San Andreas's fault is experiencing fault creep.
This is because most of the stress has been released in creeping motion and a large earthquake has not occurred.
b. The chance of occurring a major earthquake along segment 3 is very high. According to the average time schedule of 135 years, the last earthquake happened in 1857 and the next earthquake would have been in 1992. As this time has crossed, it means the next large Earthquake is going to happen soon within 2032.
c.
San Francisco is always at greater risk of experiencing a major earthquake
soon. San Francisco is just above the fault zone as compared to Los Angeles and the Earthquake probability occurrence is higher towards the San Francisco area than towards the Los Angeles area.
“Give it Some Thought” Questions Textbook pages 197-198:
Complete #’s 1 a-d, 6 a-h
1) a.
The volcano in the image is a Composite Volcano. It's high peak and very steep slope are some of the features that help us classify it.
b. Composite Volcanos usually erupt explosively, the volcano usually contains felsic magma that is very viscous. High viscosity leads to resistance and pressure build which results in a highly explosive eruption.
c. Most of the Composite Volcanoes are found along the Convergent Plate boundaries. The subduction of plate melts and forms felsic lava the erupts as an explosive volcano. d. Naples, Italy is an example which is vulnerable to such volcanic eruption. Mt. Vesuvius volcano is a volcano near the city.
6) a.
Crater Lake - a caldera volcano that formed as a result of a convergent plate boundary.
b. Hawaii's Kilauea - a shield volcano that forms at a divergent plate boundary.
c. Mount St. Helens - a stratovolcano that forms at a convergent plate boundary.
d. East African Rif - a divergent plate boundary.
e. Yellowstone - a hot spot volcano that forms at a intraplate volcanism.
f. Mount Pelée - a stratovolcano that forms at a convergent plate boundary.
g. Deccan Traps - a flood basalt that forms at a convergent plate boundary.
h. Fujiyama - a stratovolcano that forms at a convergent plate boundary.
“Give it Some Thought” Questions Textbook pages 229-230:
Complete # 4
4)
According to the hypothesis of plate tectonics, the crustal pieces transported both the oceanic plate and the crust that is subducted beneath them.
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The following phase sees these sections collide with the continental edge, causing oceanic crust to deposit at the subduction zone. Since this process has been going on for a few million years, many crustal fragments and the deposited terranes that
were the result of the collisions have been transported into the interior. As a result, the existence of an oceanic silver body within a continent's interior is supported by the idea of plate tectonics.