ENV 305 Online - Week 6 Assignment
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Wilmington University *
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ENV-305
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Geology
Date
Feb 20, 2024
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docx
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3
Uploaded by CoachSummer13763
ENV 305 Online - Week 6 Assignment
Page 123-124, question 2 (a-d): Refer to the accompanying diagrams illustrating the three types of convergent plate boundaries and complete the following: a. Identify each type of convergent boundary. b. On what type of crust do volcanic island arcs develop? c. Why are volcanoes largely absent where two continental blocks collide? d. Describe two ways in which oceanic-
oceanic convergent boundaries differ from oceanic-continental boundaries. How are they similar
a.
A - Oceanic - Continental boundary
a.
This is the boundary where heavy land mass slides down below the lighter plate.
B - Oceanic - Oceanic boundary
b.
Either of the oceanic plate due to slightly lighter mass than the other slides down creating islands above.
C - Continental - Continental boundary
c.
This boundary forms because of the plates moving towards each other creating compression force forming high mountains.
b.
Volcanic island arcs develop in
Oceanic - Oceanic
boundary.
Volcanic continental arcs
develop in oceanic-continental convergent boundary.
c.
The two solid plates are highly massive and are closely strong with each other in weight so that either of the plate gives up going down deeper into the earth while colliding. Due to low depth of intrusion into the earth, the magma won't form as temperature will be low at lower depths and hence volcanoes are formed. Though if some magma is present underneath the earth, it cannot penetrate and rise through the largely thick mass of continental plates.
Differences:
d.
In Oceanic convergent volcanoes form in oceanic plate whereas in continental oceanic boundary it forms in continental plate. Volcanic arcs forms in continental oceanic and island arcs forms in oceanic boundaries.
e.
Similarities:
f.
Both types of boundaries involve subduction. That is the process of sliding of one plate over the other due to difference in densities. Both boundaries’ forms volcanoes due to eruption of magma resulting from subduction.
Page 157-158, question 3 (a-d): Use the accompanying seismogram to answer the following questions: a. Which of the three types of seismic waves reached the seismograph first? b. What is the time interval between the arrival of the first P wave and the arrival of the first S wave? c. Use your answer from Question b and the travel-time graph in Figure 5.14 to determine the distance from the seismic station to the earthquake. d. Which of the three types of seismic waves
had the highest amplitude when it reached the seismic station? a.
The P-Waves also known as Primary Waves reached the station first, because they
are 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.
Page 157-158, question 6 (a-c): Using the accompanying map of the San Andreas Fault, answer the following questions: a. Which of the four segments (1-4) of the San Andreas Fault do you think is experiencing fault creep? b. Paleoseismology studies have found that the section of the San Andreas Fault that failed during the Fort Tejon quake (segment 3) producers a major earthquake every 135 years, on average Based on this information, how would you rate the chances of a major earthquake occurring along this section in the next 30 years? c. Do you think San Francisco or Los Angeles has the greater risk of experiencing a major earthquake in the near future? Defend your selection. a.
Segment 2 of San Andreas's fault is experiencing fault creep.
Because most of the stress has been released in creeping motion and hence large earthquake has not occurred.
b.
The chance of occurring a major earthquake along segment 3 is very high (more than 50% probability).
Because 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. (By taking +- 30 years on average time span) and the expected magnitude of earthquake is >6.0,
c.
San Francisco is always at greater risk of experiencing a major earthquake soon
.
Because 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
.
Page 197-198, question 1 (a-d): Examine the accompanying photo and complete the following: a. What type of volcano is shown? What features helped you classify it as such? b. What is the eruptive style of such volcanoes? Describe the likely composition and viscosity of its magma. c. Which type of plate boundary is the likely setting for this volcano? d. Name a city that is vulnerable to the effects of a volcano of this type. a.
In the image a Composite Volcano is shown. It is also known as a Stratovolcano. It's high peak and Glaciation, very steep slope is some of the feature that help us classify it.
b.
Composite Volcano usually erupts explosively. Its magma 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.
Most of volcanoes of Pacific Ring of Fire are examples of this.
d.
Naples, Italy is an example which is vulnerable to such volcanic eruption. Mt. Vesuvius
volcano is such a volcano near to the city.
Page 197-198, question 6 (a-h): For each of the volcanoes or volcanic regions listed below, identify whether it is associated with a convergent
or divergent
plate boundary or with intraplate volcanism
. a.
Crater Lake- Convergent
b.
Hawaii’s Kilauea- Intraplate Volcanism c.
Mount St. Helens- Convergent
d.
East African Rift- Divergent
e.
Yellowstone- Intraplate Volcanism f.
Mount Pelee- Convergent
g.
Deccan Traps- Intraplate Volcanism h.
Fujiyama- Convergent Page 229-230, question 4: Suppose that a sliver of oceanic crust were discovered in the interior of a continent. Would this refute the theory of plate tectonics? Explain. According to the hypothesis of plate tectonics, the crustal pieces transported both the oceanic plate and the crust that is subducted beneath them. 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.
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