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Asynchronous Plate Tectonics Activities developed for Teach the Earth
Module 5: Applications for Tectonic Hazards
Student Worksheet
Introduction
As we have learned so far in this lab, the plate tectonic theory is a global process that operates
on long time scales to move continents, generate mountain and island chains, and widen
oceans. In this last module we are going to look at the implications of plate tectonics on human
life both past and present.
In Part One you will be doing some detective work to solve the mystery of what plate motion
could have be responsible for historical accounts of destruction of human settlements. As plates
either subduct or grind past each other in a transform boundary, earthquakes occur.
Earthquakes that begin in underwater plate boundaries often generate tsunamis which can have
a devastating impact on nearby ecosystems and also have far reaching effects on sea level.
In Part Two we will be looking into the future and considering plate tectonics on other rocky
planets and moons by looking at a scenario where you are a planetary geologist designing a
study on tectonics for an exoplanet. In the future it is possible that geologists will need to
evaluate the tectonic hazards of possible colonization sites on these planets.
Learning Objectives
Upon completion of this module you should demonstrate your ability to:
Relate data across different kinds of datasets
Use data to infer past geological events
Begin the process of designing a research study by setting up a hypothesis and
predicting what data might support it
Lab Activity 1: Past Tectonics – Orphan Tsunamis and Ghost Forests
By most accounts, it was a dark and stormy night when Thunderbird and
Whale fought their cataclysmic battle. Darkness comes early in the Pacific
Northwest in January: the sun had been down for hours, and in the dark and
cold, no one could see Thunderbird swoop down. But they felt it when she
grabbed Whale in her talons, and rose up with it. Then she dropped Whale
from a great height, slamming it into the ground. The land shook, and the
waters receded. Some people knew to get into their canoes. Some didn't have
time. And then came the great flood, which destroyed whole villages, and lef
many canoes stranded in the trees.
That's one version of what happened that night.
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
There are many tales. In some, Thunderbird is the hero: in others, the villain.
In some, she (or he) is fighting the virtuous/evil Whale; in others, the
Transformer who creates or changes the world is her opponent. The two of
them have fought many times. Their stories are told up and down the coast.
They have changed the shape of the land. They have created and destroyed.
And their most epic battles have shaken the earth, and then caused the ocean
to roll over it. People are lef floating in the sea in their canoes without a way
to get home. Whole villages along the coast are razed. And the ones that
survive are those nearer high ground, although some of the stories also tell of
how the shaking caused whole mountainsides to come down, sometimes
burying villages beneath them. From Vancouver Island to Northern California,
variations in the story were told.
And many of them have enough details to be dated. When we do, we discover
that they refer to one winter's night in the early 1700s.
But they're just stories. Myths. Right?
-Dana Hunter
Scientific American 2016
Background
In geological science we use many data sets. Data can come from geological instruments like
seismometers or from datasets published by other earth scientists, and in some cases from
myths, folklore, and historical documents. In the early 1700s in the Pacific Northwest there are
many signs of an enormous earthquake and tsunami. You will be locating the different pieces of
evidence, making note of the locations, and generating a list of possible plate margin locations
capable of producing this earthquake and tsunami.
Evidence In North America
Open Google Earth. Use the data table below to
place pins
in approximate locations of areas
affected by the West Coast Tsunami of the 1700s. To place a pin on a location in Google Earth,
zoom in on the area, click on the pin
in the top left menu.
A box will open that will let
you type in a label and save the pin.
Take a screen shot that includes all 4 pins and
paste it into question 1 below (remove the blue text).
Evidence
Location
Thunderbird and Whale Story by the Willapa
Tribe
Willapa Bay, WA
Former fire pits
Salmon River, OR (near mouth to Pacific Ocean)
Silt and sand above buried soil (tsunami
deposits)
Twentymile River, AK
Ghost forests
Copalis River, WA
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
Figure 1 Graphic showing former fire pits in sediment in Oregon. Before the earthquake the soils were darkened and thickened
by charcoal and refuse with pits dug and filled in charcoals and fire modified rock material. Minutes to hours afer the
earthquake sand-laden tsunami waters arrived and buried the soil and hearths. Decades to centuries later we see layers in the
sediment with the charcoal layer covered with a sand layer, then a mud layer from the tides, topped with the present-day tidal
marsh sediment. Sand sheets between marsh or dune soils at the bottom and tidal mud at the top is a good indicator of a
tsunami.
Figure 2 Lef: Photograph of a ghost forest along Copalis River, December 1997. Right: Graphic showing how a ghost forest
forms when a large enough earthquake changes the ground level to be below tide level. Before the earthquake typical trees
grow. For the first few years afer the change in ground level the tide drowns the trees and they die. Centuries later, cedar trees
that have highly resistant and rigid bark do not fall over but their remains tower over the new marsh landscape. Other less
resistant trees do fall, but their stumps are buried and preserved in the mud.
Discussion Questions
1)
Print screen paste the Google Earth portion of your screen below. Please crop out your
desktop task bar.
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
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Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
Evidence In Japan
THE YEAR 1700, though almost a century earlier than the first written records from
northwestern North America, comes late in the written history of Japan. The year
belongs, moreover, to an era of Japanese stability, bureaucracy, and literacy that
promoted record-keeping. That era began with national pacification early in the 17th
century. By 1700, the country had known almost a century of peace for the first time
in 500 years… Reading and writing extended beyond this ruling elite to commoners
urban and rural. Booksellers offered poetry, short stories, cookbooks, farm manuals,
and children's textbooks. Merchants tracked goods and services in an economy driven
by bustling cities. Peasants prepared documents for villages they headed…
… PLACES FLOODED by the 1700 tsunami in Japan include Kuwagasaki, Tsugaruishi,
Ötsuchi, Miho, and Tanabe. Some of the accounts mention damage in additional
villages. In one account, the tsunami takes the form of rough seas that initiate a
nautical accident near Nakaminato
-Excerpt from The Orphan Tsunami of 1700
University of Washington Press
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
Figure 3 Image showing map locations, places, sites, and losses due to a tsunami in the year 1700 in Japan.
Discussion Questions
2)
Use the data from the figure above to
place pins
in approximate locations of areas
affected by the Orphan Tsunami of 1700. All locations are from primary sources given in
written accounts and maps from Japan. Take a screen shot of these pins and paste it
below.
A Look at Modern Data: Locating the Ghost Tsunami
Head to the Natural Hazards Viewer
https://www.ncei.noaa.gov/maps/hazards/
.
Turn off all of
the layers by clicking the boxes on the left.
Then, turn on only the Significant Earthquakes and
Plate Boundaries.
See image below:
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
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In the Viewer, the
diameter of the dot shows the magnitude
while the color shows the number
of deaths. There is a static image here:
https://ngdc.noaa.gov/hazard/data/publications/significant-earthquakes-poster.pdf (73
MB)
Look for the big circles
. This is important to our investigation because large submarine
earthquakes generate tsunamis by starting a large wave at the epicenter of the earthquake. See
figure below:
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
Figure 4 Tsunami formation
Discussion Questions
3)
Search the Pacific Ocean for the locations of plate boundaries that you think could have
triggered the change in ground level, floods, and tsunamis that we have observed.
Find
and list at least three locations
for the earthquake that could have caused the ghost
tsunami along the northwestern American coast
.
You can toggle the earthquakes off and
on so that you can see the boundaries beneath the dots. Note that a different color
scheme is used on this map: divergent is red, convergent is green, and transform is
yellow.
You might also use your map (or the key provided) from the plate boundary
exercise as an aid
.
Write a short explanation for why this plate boundary is a possibility.
Example:
The
_(type)________
boundary near
_(location)________
is a possibility because
_(your reasoning)___________.
I have seen in the lab that
_(explain)_______
generates large
earthquakes near the earth’s surface and that could change land elevation and displace large
amounts of water.
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
a)
Location 1:
The Convergent plate boundary is located on the coast of the Pacific Northwest.
This is the Cascadia Subduction Zone. The Juan de Fuca Plate is subducting beneath
the North American plate. The subduction zone can generate a large amount of
energy to release earthquakes. This will cause a powerful tsunamis and flooding
across northwestern American coast. This can change the land elevation and displace
large amounts of water.
b)
Location 2:
A transform plate boundary located near the coast of British Columbia, Canda
separating the Pacific plate from the North American plate along with part of the San
Andreas Fault. This is the Queen Charlotte Fault. This plate boundary can release
large amounts of energy to create a high magnitude earthquake. This will then
trigger a tsunami, impacting the northwestern American coast.
c)
Location 3:
A convergent plate boundary located on the northern Pacific Ocean, from the
Gulf of Alaska to Kamchatka Peninsula. This is the Aleutian Trench. The Pacific Plate is
subducting beneath the North American Plate which can lead to a large earthquake
triggering a tsunami affecting northwestern American coast.
Designing Scientific Inquiry
Thinking back to what you have learned about the scientific method, what kind of evidence
would you need to look for to test the probability of each of the locations on your list of being
the site of the 1700 earthquake? How could you find this evidence? NOTE:
Think about what
you would expect to find in other locations near each of the plate boundaries you identified.
4)
Choose one of the sites you described in the question above and determine three
possible lines of evidence you would need to support your hypothesis of this being the
site of the 1700 earthquake. Then briefly (one to two paragraphs) in the table below,
describe how you could get that evidence.
a.
Which hypothesized site of 1700 earthquake did you choose?
Cascadia Subduction Zone.
Line of Evidence
How would you get it?
1.
Sediment Cores
Sediments Cores from the ocean floor can measure the thickness of
the sediment layers along with the type of sediments. This allows past
earthquake and tsunami along with frequency of the event. If the
sediment layer is sand and debris, this could provide strong evidence
that the Cascadia Subduction Zone was the site of the 1700
earthquake.
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
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2.
Fault Scarps
Fault scarps can measure the height and length of the fault during an
earthquake. With this the magnitude could be assessed. If the scarp is
large and elongated for a long distance.
3.
Ghost Forests
Ghost forests can estimate the period of time the tsunami occurred. If
the age of the trees is related to the them time of the year 1700 this is
strong evidence Cascadia Subduction Zone is the site.
Activity 2: Future Tectonics – Exoplanet Exploration
As of this year we have identified 4197 confirmed exoplanets, or planets outside our solar
system, and 1296 are terrestrial. This means that we know of almost 1300 rocky planets that
could be colonized in humanities future. TRAPPIST-1e c is 41 light years from Earth and orbits in
the habitable zone of a dim Red Dwarf star. (FYI: NASA Exoplanet Exploration website
description:
https://exoplanets.nasa.gov/exoplanet-catalog/5501/trappist-1-c/
Retrieved
6/29/22.)
Discussion Questions
5)
Suppose that you are a planetary geologist working for NASA and we have satellites
TRAPPIST-1e and rovers on its surface. Humans plan to colonize the planet and your job
is to determine if the planet is tectonically active. What kind of observations or
information would you need to be able to evaluate possible sites for seismic or volcanic
hazards? What would each specific observation be and what would that evidence mean
in terms of plate tectonics? Fill in your answers in the table below.
Observation
Collection Method
(Image, sample, etc)
What does this information
indicate about plate
tectonics?
Seismic Monitoring
Record seismic waves with a
seismometer.
This would record any
tectonic activity and provide
data where plates are sliding
indicating activity.
Satellite Imagery
Record Features of the
surface
Fractures in the crust could
demonstrate faults which
indicate tectonic activity.
Faults demonstrate
displacement meaning
operating plate tectonics.
Volcanoes can also indicate
plate tectonics.
Volcanic Emissions
Monitoring volcanic gases
Gases like sulfur dioxide can
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson
Asynchronous Plate Tectonics Activities developed for Teach the Earth
with satellite sensors
indicate volcanic activity.
With volcanic activity this
could mean hotspots or
subduction zones are
present.
Surface Temperature
Thermal images
This can record
Mapping
detects temperature.
temperatures related to
volcanic activity or geothermal.
Suggesting source of tectonic
activity.
Developed by Kat Cantner, Eryn Klosko, Suki Smaglik, and Adrienne Sorenson