CIVENG 2J03 W2024 Assignment 4 (1)
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CIVENG 2J03: Engineering Geology
Winter 2024
Assignment #4
Due Date: March 9th, 2024, 11:59pm
This assignment is intended for individual work only, and
collaboration with others is strictly
prohibited
. By submitting your work, you affirm that you have completed the assignment independently
and have not engaged in any collaborative efforts. You
must show all your work
, including detailed
steps and calculations, as part of your submission.
All answers must be written based on the
content taught in the lecture
.
You are part of a team tasked with the construction of an apartment complex in San Franscisco area of Cal-
ifornia (Figure 1). In your team’s seismic hazard assessment of the site, the mission is to study earthquakes
to gain a better understanding of their causes, effects, and potential implications for human populations and
infrastructure. Your initial task as a team member is to conduct a comprehensive investigation into a recent
earthquake in the area. To successfully complete this assignment, you will need to apply your knowledge of
plate tectonics, seismic waves, and fault systems. Additionally, you will be expected to analyze seismic data
and present your findings in a clear and concise manner.
N
ote: This assignment includes appropriate spaces for you to record your responses to the questions. Ensure
to use the provided spaces. Keep your answers concise and brief. If you use other sources aside from class
notes, consider referencing the source using proper citations – APA style
.
Determining the epicenter of the earthquake
Seismograph data of the same earthquake has been collected from 3 different stations: Eureka in California
(Figure 2), Elko in Nevada (Figure 3), and Las Vegas in Nevada (Figure 4). This data has been provided to
you to facilitate your assessment. The following steps are required to complete the assignment.
a. Record the arrival times of the P-waves and the S-Waves.
b. Calculate the S-P wave interval.
c. Using the graph of seismic wave travel times, calculate the earthquake’s epicentral distance from each
seismic recording station. Trace the S-P wave interval along the curve and match it to the appropriate
distance.
d. Employ the method of triangulation to determine the exact location where the earthquake originated.
Answer the following questions:
1. Complete the provided table with all your recorded information.
[12 marks]
Page 1 of 6
Eureka, CA
Elko, NV
Las Vegas, NV
Location
P-wave arrival
time (s)
S-wave arrival
time (s)
Lag Time (S-P
wave interval)
Distance from the
Epicenter (km)
2. Based on the map in Figure 1, identify the location of the earthquake.
Provide evidence of your
triangulation on the figure.
[3 marks]
3. How does the global distribution of seismic stations enhance the accuracy of estimating the location
of the epicenter?
[2 marks]
4. How does the distance between the seismic station and the epicentre influence the time interval between
seismic wave arrivals?
[2 marks]
Computing Ritcher Magnitude
Now that we have confirmed the epicenter of the earthquake, the next step is to estimate its relative magni-
tude. We will utilize the nomogram in Figure 6 to determine the earthquake magnitude on the Richter scale.
Your task is to align the epicentral distance of each seismograph with its corresponding S-Wave amplitude
on the nomogram and use the intersection of these lines on the magnitude scale to arrive at the earthquake
magnitude.
Answer the following questions:
1. Fill in the respective information in the table below.
[6 marks]
Page 2 of 6
Eureka, CA
Elko, NV
Las Vegas, NV
Location
Distance from the Epicenter
(km)
S-wave Amplitude (mm)
2. Based on the nomogram, the earthquake has a magnitude of
on the
Ritcher scale.
[1 marks]
3. According to the above analysis, describe the two factors that can influence the magnitude of an
earthquake.
[2 marks]
4. Considering the location and magnitude of your earthquake, and in comparison with the Modified
Mercalli Intensity scale, determine the classification of this earthquake at the epicenter and near the
epicenter.
[3 marks]
5. Discuss the types of damage that this earthquake might have caused.
[2 marks]
6. How often can we expect the Earthquake of this magnitude to occur and what is its energy release
equivalent?
[2 marks]
Page 3 of 6
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Figure 1: Map of Western United States region
Figure 2: Eureka, CA Seismic Station seismogram (Time in seconds)
Page 4 of 6
Figure 3: Elko, NV Seismic Station seismogram (Time in seconds)
Figure 4: Las Vegas, NV Seismic Station seismogram (Time in seconds)
Page 5 of 6
Figure 5: Seismic wave travel times plot
Figure 6: Richter Nomogram
Page 6 of 6
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