Unit 2: Earthquakes, GPS, and Plate Movement
GPS data can measure bedrock motion in response to deformation of the ground near plate boundaries because of plate tectonics. In this module, students will learn how to read GPS data to interpret how the bedrock deforms and moves, both absolutely and relatively, near the plate boundary in California and how that results in earthquakes. They will then apply the skills they developed and knowledge they gained to demonstrate their understanding of how GPS data has implications for future earthquakes in the region.
Unit 2 Learning Outcomes
- Students will observe, describe, analyze, interpret, and apply time-series GPS data related to horizontal bedrock motion resulting from plate tectonics
- Students will interpret absolute and relative bedrock motion near plate boundaries and its relationship to earthquakes as measured by GPS
- Students will draw on GPS data to make a societal recommendation relative to earthquakes
Unit 2 Teaching Objectives
- Cognitive: Promote an understanding of the relationship between bedrock motion and plate movement at boundaries; provide examples of evidence of plate motion and its effects on society via earthquakes; provide students with a framework to understand relative movement of plates at plate boundaries and how that movement affects the likelihood of earthquakes
- Behavioral: Promote skills development in reading and interpreting bedrock GPS time-series data and understanding of its relationship to plate movement; provide a framework for students to approach data reading and interpretation to solve problems like a scientist; give students opportunities to draw vectors, identify trends, and calculate rates
- Affective: Encourage reflection about approaches to and difficulties with working with time-series GPS data
Context for Use
The content for Unit 2 is appropriate for introductory geology, natural disasters, environmental science, and other geoscience courses; sophomore-level courses in which geodesy is being introduced; or non-geoscience courses where the nature and methods of science are being investigated. Unit 2 activities can easily be adapted to serve small- or large-enrollment classes. They are designed to be flexible in their context and can be executed in lecture and lab settings as an in-class activity, a homework activity, and/or a collaborative lab exercise. For example,
- Activities 1 and 2 can be completed as homework, and Activity 3 can be completed as an in-class activity or lab exercise;
- Activity 1 can be completed in class, Activity 2 completed as homework, and Activity 3 completed in lab; or
- All activities can be completed in-class and/or in lab.
In the Measuring the Earth with GPS module, this unit can be used in sequence with the other units or alone. If paired with Unit 3: Glaciers, GPS, and Sea Level Rise, this unit develops skills that students have the opportunity to then build on in a supplemental activity of Unit 3. This unit is an adaptation of Exploring plate motion and deformation in California with GPS.
Description and Teaching Materials
Introductory Lecture (5–10 minutes)
This brief lecture introduction provide context for Unit 3 by introducing students to:
- A map of tectonic plates and locations of earthquakes
- Elastic rebound theory and earthquakes
- Think-pair-share asking students to brainstorm how scientists can measure plate movement and introduce the idea that GPS can be used to measure plate movement
Slides: Unit 2 Introductory slides (PowerPoint 2007 (.pptx) 11.1MB Oct14 19)
Activity 1: Observe and Describe (50–70 minutes)
In this activity, students will learn how to describe scientific data by making careful observations of it. Students will conclude by using that data to make a logical scientific interpretation. The questions guide students through the process that scientists use when they work to solve scientific questions. This particular activity uses data from GPS stations in southern California to better understand bedrock motion near transform plate boundaries.
Students can complete this handout as homework, in-class individually or in small groups, or in a lab in small groups. The graphs in the handout itself should be supplemented with the large version for easier readability (see below)—if students are working in groups, one large set of graphs per group is enough. If this is done in class, suggestions for formative assessment discussions are given in the teaching tips, below.
Student activity handout:
- Student version:
- Activity 2.1 Student Exercise (Microsoft Word 2007 (.docx) 2.6MB Jul9 19)
- Activity 2.1 Student Exercise PDF (Acrobat (PDF) 10.5MB Jul9 19)
- Full size GPS graphs for easier viewing are below, beneath Activity 3
- Instructor version with rubric:
Activity 2: Animation (10–20 minutes)
In this activity, students will watch an animation that illustrates how GPS can be used to determine the location of plate boundaries. It describes the difference between absolute motion and relative motion with regards to plate boundaries.
Students can complete this handout as homework, in-class individually or in small groups, or in a lab in small groups.
Student activity handout:
- Student version:
- Activity 2.2 Student Exercise (Microsoft Word 2007 (.docx) 202kB Jul9 19)
- Activity 2.2 Student Exercise PDF (Acrobat (PDF) 369kB Jul9 19)
- Instructor version:
- YouTube: Measuring Plate Tectonic Motions with GPS—English and Spanish closed captions are available in YouTube; click "Settings" icon and select the subtitle version of your choice
- File: Measuring Plate Tectonic Motions with GPS (MP4 Video 33.5MB Feb21 19)
Activity 3: Analyze, Interpret, and Apply (50–100 minutes)
In this activity, students will learn how to analyze and interpret scientific data after describing it. Students will conclude by using that data to support a recommendation they make about an issue relevant to society. The questions guide students through the process that scientists use when they work to solve scientific questions. This particular activity uses data from GPS stations near Parkfield, California, and southern California to better interpret plate motions near transform boundaries and earthquake risk that can be interpreted by analyzing GPS position near the plate boundary.
Students can complete this handout as homework, in-class individually or in small groups, or in a lab in small groups. The graphs in the handout itself should be supplemented with the large version for easier readability (see below)—if students are working in groups, one large set of graphs per group is enough.
Student activity handout:
- Student version
- Activity 2.3 Student Exercise (Microsoft Word 2007 (.docx) 6.4MB Jul9 19)
- Activity 2.3 Student Exercise PDF (Acrobat (PDF) 2.2MB Jul9 19)
- Instructor version with rubric:
Includes examples of higher and lower quality student work.
All graphs and original data files
Below are files with handouts, graphs, and data used throughout Unit 2. GPS data all come from https://www.unavco.org/instrumentation/networks/status/pbo
- All graphs of GPS data: Unit 2 GPS graphs (Acrobat (PDF) 1.4MB Oct7 18)
- This handout contains larger versions of the GPS graphs. You may find it helpful to have a copy of these printed out for each table group—particularly for the graphs in which the students need to calculate an annual range of motion as well as a rate.
- All Excel files of GPS data: Unit 2 GPS data (Zip Archive 7.3MB Oct4 18)
- Contains information on the data sources as well as the original spreadsheet data and graphs from which the student exercises and handouts were generated. For instructor reference or to make changes to the way data are displayed.
Teaching Notes and Tips
- Students do wrestle with some misconceptions related to what GPS data is measuring. For instance they may think the GPS station itself is moving rather than the ground it is attached to. They may also not realize that the earthquake hazard for a given area depends on the difference in movement between stations, not the movement from one station considered alone. Students also confuse positions (mm) with rates (mm/yr).
Activity 1: Observe and Describe
- If Activity 1 is done as homework, you may wish to have students compare their answers for the first few minutes of class or lab to ensure they understand it. In particular, it may be useful for them to compare their answers to Questions 3, 4, 11, 17, and 18.
- If Activity 1 is done in class, you may wish to have the students pause after certain questions for discussion. Students can compare their answers to the answers of other groups, or you may wish to lead a full-class discussion. In particular, if may be useful for them to discuss Questions 3, 4, 11, 17, and 18. For Question 4, if desired, you can assign different years to different groups, and they can compare answers across years.
- Here are slides showing the GPS data and stations to aid in class discussions, if desired (graphs are to the right of the slides): Unit 2 GPS photos, locations, and graphs (PowerPoint 2007 (.pptx) 17.6MB Jul11 19).
Activity 2: Animation
- If Activity 2 is done as homework, you may wish to have students compare their answers for the first few minutes of class or lab to ensure they understand it. Or, you may wish to show the animation again and have a full-class discussion. In particular, it may be useful for them to compare their answers to Questions 4–6.
- If Activity 2 is done in class, you may wish to have the students discuss the animation after they watch it. In particular, students can compare their answers to the answers of other groups, or you may wish to lead a full-class discussion. In particular, it may be useful for them to compare their answers to Questions 4–6.
- If you do not wish to assign the handout for students to complete while watching the animation, you can instead ask Questions 3–6, 7, and 9 as discussion questions after watching the animation.
Activity 3: Analyze, Interpret, and Apply
- We recommend that students work on Activity 3 in small groups, so they can work collaboratively to solve the problems.
- Activity 3 builds on skills learned during Activity 1 and concepts learned during Activity 2, so they should precede this activity. However, if your students are proficient at observing and describing data in graphs, it may be possible to skip Activity 1 (note that there are some concepts and skills that students build on that you may need to teach them).
- Here are slides showing the GPS data and stations to aid in class discussion, if desired (graphs are to the right of the slides): Unit 2 GPS photos, locations, and graphs (PowerPoint 2007 (.pptx) 17.6MB Jul11 19).
- The Activity 3 Answer Key includes a rubric for the more complex question related to providing earthquake hazard advice and examples of student answers. If your students struggle with how to write high-quality answers, you could consider sharing the rubrics and sample student answers and asking students to evaluate what makes a high-quality answer. This may help them improve for next time.
Activities 1 and 2 can be assessed formatively by using some of the questions as prompts for discussions, as described above in Teaching Notes and Tips. In addition, if the students are working in class or lab on the questions, the instructor can circulate and listen to student conversations and answer questions to ensure that the desired learning is occurring.
Activity 3 (as well as Activities 1 and 2, if desired) can be used as the summative assessment for this unit (Unit 2: Earthquakes, GPS, and Plate Movement). In addition to the student activity handout, the following assessments can be used as homework, quiz, or exam questions. There are open-ended and multiple-choice questions included. Also note that the Assessment page includes more general summative assessments that can be used for this unit as well.
References and Resources
This unit is an adaptation of Exploring Plate Motion and Deformation in California with GPS.
Additional Resources for Instructors:
- Students can compare their predictions for the locations of earthquakes to the USGS Earthquake Map.
- Here is a description of the 2004 Parkfield Earthquake.
- A map of the Earthquake Shaking Potential for California can be found on the California Shaking Hazard Assessment website; students can compare their predictions in Activity 3 to geoscientists' predictions (note that the hazard assessment is also dependent on other factors, such as ground type).
- The GPS Velocity Viewer allows students and instructors to view maps showing the horizontal vectors of GPS stations.
- There is a UNAVCO GPS Spotlight on Station MASW describing the 2004 Parkfield Earthquake and afterslip.
- There is a UNAVCO GPS Spotlight on Station P496, a station that experienced the same earthquake but was closer to the fault as one of the GPS stations used as part of the Assessment.
- There is a UNAVCO GPS Spotlight on Station P227 describing the slip and afterslip during and after an earthquake.
- There is a UNAVCO GPS Spotlight on Station CRBT describing high-frequency GPS observations during an earthquake.