VEPP: Using volcano deformation data for lava flow hazard assessment and decision making, Part I: what do the instruments measure?

Prajukti Bhattacharyya
University of Wisconsin-Whitewater
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This is an exercise that is in development and has not yet been fully tested in the classroom. Please check back regularly for updates and changes.

Brief three-line description of the activity or assignment and its strengths:

This is the first part of a loosely linked three part activity. Each part can be used as a stand-alone activity with slight modification. This part introduces students to volcano monitoring using data from tiltmeters and GPS receivers by means of a very simple in-class demonstration of volcanic inflation/deflation, followed by small group discussion of real data and their implications, followed by individual homework assignment based on VEPP data interpretation

Full length description:

The instructor conducts the in-class demonstration described below (demonstration takes about 20 minutes):

Put the wet sand in the tray (fill up to about three-quarters of the tray depth)

Bury the balloon in the sand. Attach the pump to the balloon.

Shape the sand above the balloon to mimic a volcano.

The balloon is the model of the magma chamber inside the volcano. While it stays relatively deflated, the "volcano" above it shows no major change in shape.

Air is then pumped in the balloon, mimicking an infusion of magma in the magma chamber. As the balloon begins to fill out, it expands, deforming the volcano above it.

The volcano is now "active" and should be "monitored" by different instruments, namely, tiltmeters, GPS, and seismometers. The carpenters' levels mimic "tiltmeters." At this point it might be useful to ask the students to select where the tiltmeters should be placed, making sure one is "tangential" and the other is "radial" (perpendicular to each other). This is a good place to start a discussion about inflation and deflation events and how those are measured by tiltmeters.

Once there is enough air in the balloon to create an obvious bulge in the volcano, the use of GPS receivers for measuring volcano deformation can be discussed. Two long pins can be used as two GPS stations and the changing distance between them can demonstrate how deformation can be measured in 3-D. At this point, several inflation-deflation events can be demonstrated by carefully letting air out of the balloon and pumping it back in.

This demonstration introduces different geophysical instruments used for volcano monitoring and provides a simplified illustration of how they work.

This demonstration is followed by a brief overview of the VEPP website and the type of data available there.

Whole class discussion about different data types (example: inflation-deflation events as recorded by tiltmeters over a specific time period). Instructor will lead the discussion and demonstrate how the data is manipulated on-line.

The VEPP overview takes 10-15 minutes

After the whole class discussion and demonstration by instructor, students break into small groups (3-4 people per group). Instructor provides printed data plots for tiltmeters and GPS time series for the same time period. A map showing the locations of the corresponding instruments is also provided. Different groups get data for different time periods/eruption events. An example plot with clearly marked inflation/deflation events and instructions about how to read the plots will be helpful

Questions for students to answer in small groups:

  1. Identify the dates/times when tiltmeters record inflation events
  2. Identify dates/times when tiltmeters record deflation events
  3. What does the GPS data show for each of those time periods?
  4. What can you infer about the volcanic activity for those time periods from the data provided?

Small group discussion takes 15-20 minutes

Each group report back and compare their interpretations. Instructor facilitates discussion/provides feedback (20 minutes)

Instructor then demonstrates the webcam images/movies from the VEPP site for the same time periods/events as the data provided to the student groups so they can see whether they interpreted the data correctly or not. This is followed by discussion about uncertainties/ambiguities associated with real data and data interpretation. (10-15 minutes).

Used this activity? Share your experiences and modifications

Learning Goals

Learning goals for part I of the activity

ยท Students will analyze different types of geophysical data (tiltmeter data, continuous GPS data, and webcam images) available through the VEPP site, and identify how these datasets reflect different volcanic activities over time periods ranging from minutes (tiltmeters and webcam) to years (GPS data)

content/concepts goalsfor this activity

  • Volcanic deformation processes before, during and after an eruption
  • How tiltmeters and GPS data are collected and used for volcano monitoring
  • Different volcanic events (gas pistons, lava fountains, lava lake overflow etc.) and the processes leading to those events

Briefly describe the higher order thinking skills goalsfor this activity

  • Analysis of real geophysical data for identifying volcanic activity
  • Synthesis of data collected by different instruments like tiltmeters, GPS, and webcam, and use them for predicting volcano behavior
  • Evaluate the errors associated with the data (e.g.instrument failure, rainfall or other factors influencing the data)

Briefly describe any other skills goals for this activity

  • Collaboration skills for working in small groups
  • Quantitative skills such as graph reading and vector addition

Context for Use

What is the type of activity (a problem set, classroom activity, lab activity, project, field activity, and/or a writing activity)?

This is a studio type activity with a combination of in-class demonstration, brief lecture, small group activity and large group discussion, followed by a homework assignment

What is the class type (small intro lecture, large intro lecture, or UD/grad course; disasters, hazards, field course, or intro geology; with or without computers; community college)?

Small intro lecture (20-24 students) in a 2- year or 4 year college

Briefly describe the type(s) and level(s) of course in which this activity or assignment could be used (e.g., undergraduate required course in structural geology, introductory physical geology course for non-majors, graduate level seminar on geochemistry):

Lower division undergraduate natural science courses for non-majors (such as natural hazards or volcanoes). This activity can also be used as a module in introductory physical geology course.

Briefly describe or list the skills and concepts that students must have mastered before beginning the activity:

Basic graph reading skills (determine the value of the dependent variable based on the independent variable, identify trends and anomalies on a graph


Definition of a volcano and parts of a volcano

Volcano vocabulary (magma chamber, lava, magma, summit, flank, crater, caldera, viscosity, pressure, volatiles... etc.)

Briefly describe how the activity is situated in your course (e.g., as a culminating project, as a stand-alone exercise, as part of a sequence of exercises):

This is intended to be the first part of a series of three exercises, but it can be used as a stand-alone exercise with minimum modification

Description and Teaching Materials

Wet sand, balloon, pump, small tray with about 3 inch depth, carpenters' level (at least two), toothpicks or pins with colored heads

Archived tiltmeter and GPS data plots generated by VEPP and corresponding excel CSV files as and when available

Map showing location of Puu O'o vent and those of the tiltmeters and GPS receivers used for data collection

Volcano monitoring data from VEPP web site for specific events.

Computer with internet connection in classroom.

Teaching Notes and Tips

Accessing the VEPP Web site ( requires a password, which can be obtained by sending an email with your name, affiliation, and intended use of the site to mpoland "at"

Please describe any helpful examples of this activity, as well as any potential variations on this theme:

What tips might you offer to other educators planning to use this activity?


Describe briefly how you determine whether students have met the goals of this assignment or activity.

The activity is followed by a homework assignment to be submitted individually.

Each student is assigned specific time periods for which they have to:

  1. Access tiltmeter (both radial and tangential) data
  2. Generate plots and vector maps,
  3. Identify D-I events for their data and determine the direction of tilt for each inflation and deflation event from the vector plots
  4. Access GPS time series data and determine what the GPS data was showing for each inflation and deflation event
  5. Access the web cam archive to obtain images for that time period, create a movie with the images and describe what was going on at that time.
This homework assignment is due before the next class period, and is graded.

References and Resources

Please list any supporting references or URLs for this activity:

Using volcano deformation data for lava flow hazard assessment and decision making, Part I: what do the instruments measure? --Discussion  

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