GETSI Teaching Materials >GPS, Strain, and Earthquakes > Unit 3: Getting started with GPS data
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This module is part of a growing collection of classroom-tested materials developed by GETSI. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
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Unit 3: Getting started with GPS data

Vince Cronin, Baylor University (Vince_Cronin@baylor.edu)
Phil Resor, Wesleyan University (presor@wesleyan.edu)

These materials have been reviewed for their alignment with the Next Generation Science Standards as detailed below. Visit InTeGrate and the NGSS to learn more.

Overview

Students analyze and interpret GPS data to calculate the motion of the crust. The Pythagorean Theorem (algebra) is used to calculate total velocity from two vectors.

Science and Engineering Practices

Using Mathematics and Computational Thinking: Use mathematical, computational, and/or algorithmic representations of phenomena or design solutions to describe and/or support claims and/or explanations. HS-P5.2:

Developing and Using Models: Develop and/or use a model (including mathematical and computational) to generate data to support explanations, predict phenomena, analyze systems, and/or solve problems. HS-P2.6:

Analyzing and Interpreting Data: Consider limitations of data analysis (e.g., measurement error, sample selection) when analyzing and interpreting data HS-P4.3:

Analyzing and Interpreting Data: Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution. HS-P4.1:

Cross Cutting Concepts

Stability and Change: Change and rates of change can be quantified and modeled over very short or very long periods of time. Some system changes are irreversible. HS-C7.2:

Patterns: Mathematical representations are needed to identify some patterns HS-C1.4:

Disciplinary Core Ideas

Wave Properties: Information can be digitized (e.g., a picture stored as the values of an array of pixels); in this form, it can be stored reliably in computer memory and sent over long distances as a series of wave pulses. HS-PS4.A2:

Performance Expectations

Earth's Systems: Construct an explanation based on evidence for how geoscience processes have changed Earth's surface at varying time and spatial scales. MS-ESS2-2:

  1. This material was developed and reviewed through the GETSI curricular materials development process. This rigorous, structured process includes:

    • team-based development to ensure materials are appropriate across multiple educational settings.
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    • real in-class or field camp/course testing of materials in multiple courses with external review of student assessment data.
    • multiple reviews to ensure the materials meet the GETSI materials rubric which codifies best practices in curricular development, student assessment and pedagogic techniques.
    • created or reviewed by content experts for accuracy of the science content.

  2. This activity was selected for the On the Cutting Edge Exemplary Teaching Collection

    Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories. The five categories included in the peer review process are

    • Scientific Accuracy
    • Alignment of Learning Goals, Activities, and Assessments
    • Pedagogic Effectiveness
    • Robustness (usability and dependability of all components)
    • Completeness of the ActivitySheet web page

    For more information about the peer review process itself, please see https://serc.carleton.edu/teachearth/activity_review.html.



This page first made public: Dec 9, 2016

Summary

This unit provides essential background information on GPS (global positioning system) and reference frames. Students learn how to access GPS location and velocity data from the Plate Boundary Observatory (PBO). They calculate total horizontal motion graphically and mathematically and tie the observed motions to local strain.

Note: Although the term GPS (Global Positioning System) is more commonly used in everyday language, it officially refers only to the USA's constellation of satellites. GNSS (Global Navigation Satellite System) is a universal term that refers to all satellite navigation systems including those from the USA (GPS), Russia (GLONASS), European Union (Galileo), China (BeiDou), and others. In this module, we use the term GPS even though, technically, some of the data may be coming from satellites in other systems.

Learning Goals

Unit 3 Learning Outcomes

Unit 3 Teaching Objectives

  • Cognitive: Facilitate student ability to solve infinitesimal strain calculations using multiple quantitative methods and to qualitatively describe the connection between GPS velocities and strain.
  • Behavioral: Provide an opportunity for students to access and download GPS data.

Context for Use

This module was designed for structural geology courses but can also be successfully used in geophysics, tectonics, or geohazards courses or possibly even a physics or engineering course seeking practical applications. It can be done at most any point during the term. The module assumes that students have had a basic physical geology introduction to plate tectonics, faults, and earthquakes. Students gain the strongest intuitive understanding of strain (Unit 2: Mashing it up: Physical models of deformation and strain) and the human impacts of earthquakes (Unit 1: Earthquake!) if these prior units are used. However, Unit 3 can be done without these preceding units if students are familiar with the terminology related to strain, strain ellipses, translation, rotation, etc. Unit 3 is intended as the precursor to Units 4–6, teaching the students essential skills in GPS data access.

Description and Teaching Materials

Start out the class with the presentation "Introduction to GPS." This gives an overview of GPS from applications students are familiar with (phones, cameras, etc.) and then introduces high-precision scientific GPS instruments and data. The students then do an exercise in which they access the Plate Boundary Observatory data to locate stations and find the precise coordinates and velocity. After the introduction, the exercise can be done in class or at home. The exercise does require Internet, so for classes without easy access to computers, it maybe easier to do as a homework assignment. If the exercise is done in class, students can work in groups of three—each finding the data for one of the stations and then compiling the data. After the exercise is complete, another short presentation is provided for the instructor to go over the findings from the exercise and come to a better understanding of the ongoing strain in the coastal Oregon. Although no graded reflections are included in the exercise, the wrap-up presentation can be a good time to pose reflection questions to the class, such as "Did anything about this exercise particularly surprise or confuse you?" "What other areas interest you to explore in this way and why?"

Teaching Notes and Tips

  • We also provide supporting math materials in Unit 2 for instructors interested in having students take the quantitative analysis to a deeper level. These include vector, matrices, and infinitesimal strain analysis background.
  • Before turning the students loose to do the exercise in class or for homework, it may help to pick some other station in the western United States to walk them through the process. Have them watch while you go to the PBO website and find a station of interest. Show them how to find the velocity measurements by clicking through to the "detrended" time series (also described in their exercise, but seeing it in advance does seem to help). You can also show them how to view pictures of the GPS station. That seems to make it more real for them.
  • If you are ever interested in having students generate vector maps for other GPS stations besides the ones featured in this module, you can use this Adobe Illustrator file as a starting point. GPS Triangle Vector Map (Adobe Illustrator) (Zip Archive 2.2MB Nov18 16)
  • The concepts of translation, rotation, and strain ellipses are covered more completely in Unit 4: GPS and infinitesimal strain analysis, but in the Unit 3 exercise students are asked to make conceptual estimates for these characteristics for the three example stations in Oregon. They may need some guidance on applying what they saw in Unit 2: Mashing it up: Physical models of deformation and strain with the vectors they are now looking at. Instructors may wish to remind themselves of these concepts before teaching. Explanation of GPS Strain Calculator output PDF (Acrobat (PDF) 1.1MB Dec28 17) may be helpful to review.

Assessment

Observation of student activity and conversations, individual questioning, and group discussion are excellent ways to conduct formative assessment as the students complete this exercise.

Summative Assessment:

The student exercise is the summative assessment for this unit. Most of the questions have definite right or wrong answers. To receive full credit, students must show their work, where appropriate. Where an open-ended answer is required, students are assessed based on a simple 2-point system.
2 points = correct answer with thorough supporting evidence and/or complete description
1 point = answer not completely correct or lacking thorough supporting evidence or description
0 points = incorrect answer

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This module is part of a growing collection of classroom-tested materials developed by GETSI. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
Explore the Collection »