Megathrust Earthquakes Educator Guide
A resource for using QUEST Northwest video in the classroom; created by PBS partner station KCTS 9
PROGRAM NOTES
QUEST
SUBJECTS
Watch it online http://science.kqed.org/quest/video/megathrust-earthquakes/
Life
Science
Biology
Health
Environment
Earth
Science
Geology
Climate
Weather
Astronomy
Physical
Science
Physics
Chemistry
Engineering
WA SCIENCE
STANDARDS
6-8 ES2F
The crust is composed of huge
crustal plates on the scale of
continents and oceans which
move centimeters per year,
pushed by convection in the
upper mantle, causing
earthquakes, volcanoes and
mountains
6-8 ES3D
Our understanding of Earth
history is based on the
assumption that processes we
see today are similar to those
that occurred in the past.
6-8 ES3D
Earth has been shaped by many
natural catastrophies, including
earthquakes, volcanic eruptions,
glaciers, floods, storms, tsunami,
and the impacts of asteroids.
9-11 ES3B
Geologic time can be estimated
by several methods (e.g.
counting tree rings, observing
rock sequences, using fossils to
correlate sequences at various
locations, and using the known
decay rates of radioactive
isotopes present in modern day
rocks to measure the time since
the rock was formed).
QUEST explores the most powerful earthquakes on the planet – megathrust
earthquakes. Experts warn that an offshore quake powerful enough to kill thousands and
discharge a tsunami could hit the west coast anytime. Quest camera crews talk with
geologists and seismologists about cutting edge research in earthquake prediction, and
what it would look like if the next “big” one hits close to home.
In this segment you’ll find…
۞ an explanation of megathrust, shallow crust, deep crust and slow slip earthquakes.
۞ the impact of a megathrust earthquake along the Cascadia fault.
۞ how scientists are studying the past to help predict future earthquakes.
TOPIC BACKGROUND
The Pacific Northwest is a tectonically active region that’s constantly changing. It makes
for beautiful mountains and scenery - it also makes for a big hazard.
This area is prone to all three types of earthquakes; shallow, deep and megathrust.
Shallow earthquakes occur along crustal faults near the surface of the Earth. Most
shallow quakes are a magnitude of 7.5 or below, but they can cause a lot of damage
because they’re so close to the surface. Deep quakes occur along fault lines 30-70
kilometers below the surface of the Earth. They typically have a magnitude of less than
7.5, but are felt over a large area. While shallow quakes and deep quakes have the
potential for widespread damage depending on where they hit, they are no comparison to
a megathrust earthquake. Megathrust earthquakes have a magnitude of 9 or greater and
the shaking can last anywhere from three to six minutes. Megathrust earthquakes occur
along subduction zones where the Earth’s tectonic plates are colliding. The pressure
between the plates builds over time and eventually releases leading to huge geologic
upheaval and the birth of a tsunami wave. In the Pacific Northwest’s Cascadia
Subduction Zone, the oceanic Juan de Fuca plate is subducting under the thicker North
America continental plate. The Cascadia Subduction Zone runs from Northern California
to Vancouver Island. If a megathrust hit, it would affect every city on the west coast from
San Francisco to Vancouver, BC. Megathrust earthquakes happen about every 500
years. Scientists have determined that the last one was in 1700. Bottom line -- we’re due.
Geologists are studying past events to determine when the last megathrust quake hit the
Cascadia region. Layers of sand found far inland are an indicator of past tsunamis and
dendrochronologists are able to date ghost forests to determine when the last megathrust
quake occurred. A picture of past events will help us to determine what might happen in
the future.
Megathrust Earthquakes Educator Guide
science.kqed.org/quest
PRE-VIEWING
VOCABULARY
Cascadia Fault
the convergent plate boundary
of the oceanic Juan de Fuca
plate and the continental North
American plate that stretches
from northern Vancouver
Island to northern California.
Deep earthquake
an earthquake that occurs 3070 km below the Earth’s
surface.

Have you ever experienced an earthquake?

What is a megathrust earthquake?
VIEWING FOCUS
NOTE: You may choose to watch the television segment twice with your students: once
to elicit emotional responses and get an overview of the topic and again to focus on facts
and draw out opinions.

How are megathrust earthquakes different from shallow and deep earthquakes?
Dendrochronology
the study of climate changes
and past events by comparing
the successive annual growth
rings of trees.

Where do megathrust earthquakes occur?

What is a slow slip earthquake?

What are the benefits of being able to predict earthquakes?
Fault
a crack in the earth’s surface
across which there has been
relative displacement.
For all media see:
 Segment Summary Student Sheet
http://www.kqed.org/quest/downloads/QUEST_SegSum_StudentSheet.pdf
 Personal Response Student Sheet
http://www.kqed.org/quest/downloads/QUEST_PersResp_StudentSheet.pdf
Liquefaction
liquefaction occurs when
vibrations in the ground cause
water saturated soils to settle
and behave like a liquid rather
than a solid.
Megathrust earthquake
a large powerful earthquake
occurring along a subduction
fault where an ocean plate is
sliding beneath a continental
plate.
Seismometer
an instrument that measure
motions of the ground.
Shallow earthquake
an earthquake that occurs less
than 25 km below the Earth’s
surface along a crustal fault.
Slow slip earthquake
a long (30-40 days), lowfrequency earthquake.
Subduction zone
a region where two
lithospheric plates collide, with
one plate sliding beneath the
other.
Tsunami
a large ocean wave produced
by sudden movement on the
ocean floor caused by an
earthquake or volcanic
eruption.
LESSON PLANS and RESOURCES from NET, QUEST, PBS and NPR
On Shaky Ground: Earthquakes in the Pacific Northwest
http://kcts9.org/on-shaky-ground
In this special report, KCTS 9 shows the types of powerful earthquakes that pose the
greatest risk to our region, how local leaders are preparing for the next big quake, and
what you should be doing to protect your home and your family.
NOVA Japan's Killer Quake - PBS
http://www.pbs.org/wgbh/nova/earth/japan-killer-quake.html
An eyewitness account and investigation of the epic earthquake, tsunami, and nuclear
crisis in Japan March, 2011.
Pacific Northwest Seismic Network (PNSN)
http://www.pnsn.org/
All about earthquakes and geologic hazards of the Pacific Northwest.
Earthquakes Teachers’ Domain
http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.lp_earthquakes/
In this lesson, students explore the causes of earthquakes and their impact on human
societies and the geology of an area.
Plate Tectonics Teachers’ Domain
http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.lp_platetectonics/
Through class discussion, videos and activities, students seek connections between
tectonic activity and geologic features and investigate how the theory of plate tectonics
evolved.
Earthquakes Lesson Plan Teachers’ Domain
http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.lp_earthquakes/
In this multimedia-infused lesson, students explore the causes of earthquakes and their
impact on human societies and the geology of an area
Megathrust Earthquakes Educator Guide
science.kqed.org/quest
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MORE EDUCATIONAL RESOURCES FOR USING QUEST MULTIMEDIA TO
ENHANCE 21st CENTURY SKILLS IN TEACHING AND LEARNING
Why Use Multimedia in Science Education?
http://www.kqed.org/quest/downloads/QUESTWhyMedia.pdf
 Read about the importance of using multimedia in the 21st century
science classroom.
How to Use Science Media for Teaching and Learning
http://www.kqed.org/quest/downloads/QUESTMediaTips.pdf
 A collection of tips, activities and handouts to actively engage students
with multimedia.
Science Multimedia Analysis
http://www.kqed.org/quest/downloads/QUESTMediaAnalysis.pdf
 Give your students the tools to recognize the purposes and messages of
science multimedia.
Create Online Science Hikes with Google Maps
http://www.kqed.org/quest/files/download/52/QUEST_ExplorationCreation.pdf
 Do you like the science hike Explorations on the QUEST site? Use this
place-based educational guide to create similar science-based maps with
youth.
Media-Making Toolkit for Science Education
http://science.kqed.org/quest/education
 Are you interested in integrating media making into your classroom or
science education program? Find instructions, worksheets and rubrics for
implementing simple media-making projects with students.
MORE QUEST
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This Educator Guide was created by QUEST KCTS, a PBS partner station.
To learn more about this partnership, please visit:
http://science.kqed.org/quest/station/northwest/
Major funding for QUEST is provided by the National Science Foundation and the Corporation for Public Broadcasting. Additional support is provided by the
Richard and Rhoda Goldman Fund, the S. D. Bechtel, Jr. Foundation, the Dirk and Charlene Kabcenell Foundation, the Vadasz Family Foundation, the
Wyncote Foundation, and the George and Jeanette Stuart Charitable Trust.
© 2011 KQED, San Francisco and © 2011 KCTS Television