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Episodic tremor and slip: The Case of the Mystery Earthquakes

Index


Goal

Students are able to describe Episodic Tremor and Slip (ETS) as it occurs along the Cascadia Subduction Zone in the Pacific Northwest.


Context

Audience

This lesson was developed for high school and middle school students, grades 6 - 12. However, its focus on data makes it adaptable for introductory college courses.

Teaching Time

Two class sessions (45 - 55 minutes)

Skills and concepts that students must have mastered

Students must be able to read a graph. If they flounder, the activity “Introduction to graphing GPS data” is designed for novice graphers.

How the lesson is
situated in the course

This lesson can stand alone or with other lessons about plate tectonics and convergent boundaries

Next Generation Science Standards

Performance Expectations: MS-ESS2-2, MS-ESS3-2, and HS-ESS3-1.

Objectives

Students will be able to:

  • Describe the tectonic setting of Cascadia
  • Interpret GPS time series plots (position vs. time) qualitatively;
  • Identify and describe patterns of ETS in seismic and GPS data
  • Model ductile and brittle behavior
  • Summarize geological and societal implications of ETS.

Summary

Earthquakes in western Washington and Oregon are to be expected—the region lies in the Cascadia Subduction Zone. Offshore, the Juan de Fuca tectonic plate subducts under the North American plate, from northern California to British Columbia. The region, however, also experiences exotic seismicity— Episodic Tremor and Slip (ETS).

In this lesson, your students study seismic and GPS data from the region to recognize a pattern in which unusual tremors--with no surface earthquakes--coincide with jumps of GPS stations. This is ETS. Students model ductile and brittle behavior of the crust with lasagna noodles to understand how properties of materials depend on physical conditions. Finally, they assemble their knowledge of the data and models into an understanding of ETS in subduction zones and its relevance to the millions of residents in Cascadia.

This lesson has an optional prequel, “Introduction to graphing GPS data,” designed for students who cannot yet graph earth science data skillfully or confidently. Its first two parts teach students to graph position vs. time, and its last part dovetails with this lesson. It teaches about velocity vectors by graphing position data over five years.

Organization

This lesson consists of four principle parts:

  1. Introducing or reviewing the Cascadia Subduction Zone.
  2. Analyzing unusual seismic signals coincident with unexpected GPS data (after students learn to interpret GPS data). Exploration of physical models complements data analysis.
  3. Making sense of the data and models in the context of a subduction zone.
  4. Recognizing implications of ETS for people in Cascadia and around the Pacific Rim.


Download Materials

Teacher materials



All teacher and student files bundled

81 MB • v: April 16, 2014



Individual files:

Teacher guide for Lesson: Episodic tremor and slip: The Case of the Mystery Earthquakes. [pdf]

[docx]

1 MB • v: April 16, 2014


Presentation: Episodic tremor and slip: The Case of the Mystery Earthquakes. [pptx]

[pdf]

35 MB • v: April 16, 2014

This PowerPoint accompanies the lesson.


Student materials

Student Worksheet for Lesson: Episodic tremor and slip: The Case of the Mystery Earthquakes. [pdf]

[docx]

1 MB • v: April 16, 2014


Prequel activity: Introduction to graphing GPS data

This lesson has an optional prequel, “Introduction to graphing GPS data,” designed for students who cannot yet graph earth science data skillfully or confidently. Its first two parts teach students to graph position vs. time, and its last part dovetails with this lesson. It teaches about velocity vectors by graphing position data over five years.

Related Lessons

coming soon

 
 
 
 
 
 
 



Module Development

Funding for this unit came from the Plate Boundary Observatory, NSF, the American Recovery and Reinvestment Act, NASA, and UNAVCO. Authors are Roger Groom (Mt. Tabor Middle School), Shelley Olds (UNAVCO), Herb Dragert (Geological Survey of Canada), Bob Butler (U. Portland), Jenda Johnson (IRIS), and Nancy West (Quarter Dome Consulting).


Last modified: Thursday, 09-Nov-2017 22:47:43 UTC

 

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