HW_USGS eq tracking
docx
keyboard_arrow_up
School
Temple University *
*We aren’t endorsed by this school
Course
836
Subject
Astronomy
Date
Dec 6, 2023
Type
docx
Pages
3
Uploaded by CoachDuckMaster829
EES 0836
USGS Earthquake Tracking Assignment
Disasters: Geology vs. Hollywood
Introduction
Just because most earthquakes are not felt by people doesn’t mean they do not happen. Because we have
seismic stations located throughout the United States (and beyond), we know that earthquakes happen all
of the time. This exercise uses the U.S. Geological Survey’s “Latest Earthquakes” map, which is updated
every couple of minutes, to help reveal the frequency of these events.
Learning Objectives
●
Describe the value of an earthquake's epicenter and focus to infer tectonic processes driving them.
(3, 5, b, c)
●
Identify the relationship between magnitude and frequency.
(3, 5, d)
Part 1:
U.G. Geological Survey map
Follow these initial instructions to get started, then answer the series of questions below based on the data
on the website.
A.
Navigate to
https://earthquake.usgs.gov/earthquakes/map/
B.
The “Zoom to…” box in the upper right of the map will allow you to quickly navigate to
different places. Start by selecting “World”.
Note: The continents repeat in this view, but zooming in to the next level cuts off some of the
whole picture, so we’ll stay here for now.
C.
Click on “show legend” at the bottom of the map.
a.
Each circle represents an earthquake epicenter.
b.
The magnitude of the event is reflected in the size of the circle.
c.
The color of the circle indicates the age of the event.
d.
Clicking on any circle will bring up the stats for that particular earthquake on the bottom
left of the page.
D.
Feel free to look around to familiarize yourself with the page. If you do change the information
displayed, make sure you default back to the information we started with in A.
Questions:
Let’s start by examining the overall global pattern of earthquakes, magnitude 4.5 and over, in the last 30
days.
1.
In what geographical area(s) do most of the earthquakes on the map cluster?
Mostly in the ocean along Australia and Asia as well with some off the western coast of
South America
2.
Are the places you listed associated with plate boundaries?
Yes, these earthquakes are associated with the plate boundaries.
EES 0836
3.
If you answered yes to Question 2, what type of plate boundaries (divergent, convergent,
transform) are they? (
If you answered no to Question 2, skip this question.
)
The plate boundaries are convergent.
Locate the “Zoom to…” menu in the top right of the page and select “U.S.”
4.
In the last 30 days, have most of the earthquakes of magnitude 4.5 or higher been in the western,
central, or eastern part of the country?
All of the earthquakes that have happened have been on the western coast of the United
States towards the northern border
5.
Does this make sense given the distribution of known active faults in the country? Why or why
not?
Yes, this does make sense of the distribution of earthquakes because the active faults in the
United States are along the west coast.
Using the gear icon in the top right of the page, change your setting to “30 Days, Magnitude 2.5+ U.S.”
Click back and forth between the “Magnitude 4.5+” and “Magnitude 2.5+” settings a couple of times to
get a sense of how the number and geographical distribution of earthquakes changes when you include
the smaller magnitude events. Finish at the “Magnitude 2.5+” setting.
6.
What can you say in general about the relationship between earthquake magnitude and frequency
of occurrence?
Seems like the lower magnitude earthquakes occur more often than the higher magnitude
ones.
7.
What can you say in general about the relationship between earthquake magnitude and whether it
occurs on a plate boundary or not (intraplate earthquakes)?
So it appears that the higher the magnitude the closer it is to the plate boundaries as the
smaller the magnitude it is farther away from the boundary but tends to occur more often
than the higher magnitude earthquakes.
On the “Zoom to…” menu, now select “Hawaii”. Click back and forth between the “30 Days, Magnitude
4.5+” and “30 Days, Magnitude 2.5+” settings a couple of times again to get a sense of how the number
and geographical distribution of earthquakes changes when you include the smaller magnitude events.
Finish at the “30 Days, Magnitude 2.5+” setting.
8.
Hawaii is the most seismically active state in the U.S., even though it is not on a plate boundary,
but the quakes tend to be small and very geographically concentrated. What is the source of the
EES 0836
earthquakes in Hawaii?
The earthquakes in Hawaii are most likely due to the many amounts of volcanoes that the
islands possess which makes them more vulnerable to earthquakes.
On the “Zoom to…” menu, now select “Alaska”. Change the magnitude setting back to “30 Days,
Magnitude 4.5+” to get a more manageable data set. We are going to focus on the earthquake epicenters
along the Aleutian Trench and the plate boundary associated with it.
9.
Click on the circles for the individual earthquake epicenters in the general region of the trench.
When the stats for each earthquake come up, pay particular attention to the “Depth” information.
This tells you how deep below the surface the actual focus of the earthquake was. You should be
able to notice a general relationship between the depth of the earthquake foci and the distance of
the earthquake from the trench itself. What is that relationship?
The closer to the trench the deeper the focus of the depth is which is usually 30-45
kilometers of range with some being around 10 kilometers down.
10.
Why do you think this relationship exists? (Hint: What’s the tectonic situation at this plate
boundary?)
This relationship exists because you have a trench that is most likely on a convergent plate
boundary causing earthquakes.
Now draw your attention to the east coast of the United States. Change your magnitude setting to “30
Days, Magnitude 2.5+U.S.”
11.
How many earthquakes have occurred here in the past 30 days?
Four earthquakes
12.
If you were to do this same assignment 30 days from now, would you expect to see more, less, or
about the same number of earthquakes in this region? Explain your thinking.
If I was to do this same assignment in another 30 days, I would most likely find the same
number of earthquakes because there is not many faults or disturbance along the east coast,
and is not along any plate boundaries so, therefore, I think it would remain pretty constant
for the most part.
13.
There are several geologic features that were produced when Pangea began to break up around
200 million years ago. Among these features are faults. What type of fault would you expect to
see forming during the breakup of a continent? Explain your reasoning.
I think you would see a normal fault that would cause the breakup of the continents because
most faults tend to break off pieces so an enormous fault could’ve set everything off.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help