VEPP: Analysis of Inflation-Deflation Events at Pu'u 'Ō'ō Using Tiltmeter Data

Jascha Polet, California State Polytechnic University, Pomona
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Brief three-line description of the activity or assignment and its strengths (you will have an opportunity to expand on this description later in the form):

This activity is a homework exercise with an introductory classroom lecture and demonstration component. It may be used in large lecture classes and does not require students to have access to computers in the classroom. Students are asked to use the VALVE interface to retrieve, plot and interpret tilt time series and vector maps for inflation/deflation events at Pu'u 'Ō'ō in the past and possibly present.

This is a work in progress, not yet tested in a classroom setting, and examples of a PowerPoint lecture and pdf homework assignment will be uploaded before the start of Spring quarter 2011. All data required is currently already available from the VALVE interface.

Used this activity? Share your experiences and modifications

Learning Goals

Briefly describe the content/concepts goals for this activity (e.g., those involving pure vs. simple shear, deformation mechanisms, kinematic analysis, accurate description of samples):

Students should be able to:

  • Describe how tiltmeters work and how their data is used in the monitoring of active volcanoes
  • Explain how tiltmeter measurements are related to physical changes in a magma chamber
  • Describe what tiltmeter time series and vector maps, as produced by the Valve interface, show
  • Discuss how tiltmeters might be able to indicate deformation that is not obvious from simple observations

Briefly describe the higher order thinking skills goals for this activity (e.g., those involving analysis of data, formulation of hypotheses, synthesis of ideas, critical evaluation of competing models, development of computer or analog models):

Students should be able to:

  • Interpret time series and vector maps of tilt in terms of Pu'u 'ÅŒ'ō inflation/deflation events, and relate the two types of data representation to each other
  • Identify inflation/deflation events by examining Pu'u 'ÅŒ'ō tiltmeter data and correlate rainfall data with tilt data to determine whether observed ground tilts are due to volcanic activity or heavy rainfall
  • Use deductive reasoning to compare and contrast tiltmeter datasets for different time periods and determine the physical meaning of any differences
  • Predict future and/or describe current behavior of Pu'u 'ÅŒ'ō in terms of inflation/deflation based on previous events and tiltmeter/rainfall data for the past week

Briefly describe any other skills goals for this activity (e.g., those involving writing, operating analytical equipment, searching the WWW, oral presentation, working in groups):

Students should be able to:

  • Follow step-by-step instructions to use an online interface to replicate a given plot
  • Demonstrate proficiency with the use of an online interface to retrieve and plot tiltmeter and rainfall data for a specified set of input parameters without step-by-step instructions
  • Write a paragraph explaining map vectors and time series of tilt in terms of physical processes at Pu'u 'ÅŒ'ō
  • Argue for the existence of a inflation/deflation event in the data based on comparison with data of a given event

Context for Use

This activity is intended for use of both majors and non-majors.
Intended for undergraduate upper division students
Typical Number of Students: 30-60
Typical Number Classes Where Exercise is Used: one-two hours of lecture + homework exercise
Data accessed outside of class

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

The activity is a problem set, to be assigned after an introduction in the classroom in a lecture/demonstration format.

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)?

Relatively large upper division General Education lecture course on Natural Disasters, without computers.

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):

An upper division general education course.

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

The exercise should be part of a general discussion of volcano monitoring. The students should have a basic background in volcanoes, magma chambers and magma movement, volcanic hazards. It would be useful if students already have some experience in accessing datasets through the internet.

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):

As one of a series of homework exercises assigned during the quarter.

Description and Teaching Materials

Full length description:

The following activity would be part of a general discussion of the importance of (real-time) volcano monitoring and the different types of tools that are available to geoscientists and the types of signals that may occur prior to eruption events. I personally will be emphasizing the high-tech and near real-time nature of the data/instruments, and the fact that it may also show volcanic processes at work that are not visible to the naked eye. It is essential that the instructor carefully covers the material on The VEPP Tilt Page and the VEPP Inflation-Deflation Example prior to assigning the exercise, and also demonstrates the use of the VALVE interface.

The following paragraphs describe the material that should be covered by the instructor in the classroom.

Discuss how tilt meters work, using the information on The Tilt Page. Another description of tilt meters can be found at Tunnel tiltmeters, Pozzuoli, Italy. A useful (but possibly time-consuming) activity would be the Building of a Water Tube Tilt Meter. A somewhat shorter alternative demonstration is [link When will it blow? – How a simple tiltmeter can demonstrate the bulging of a volcano before eruption'].

Discuss the Inflation-Deflation Example, in particular the two animations that show the time series of tilt that are expected for these types of events. In addition to the Kilauea example, possibly show the example of Mount St. Helens. Other useful animations may be found on the IRIS volcano Monitoring page.

Show the tilt station location map on The Tilt Page and discuss the meaning of the radial and tangential component in this context.

Cover the example Deflation-Inflation (DI) event at the bottom of The Tilt Page. Explain what the graphs show (refer back to tilt station map) and the possible problem associated with heavy rainfall. Use worksheets and Think-Pair-Share questions on graph reading and interpretation. Cover how sensitive these tilt meters are, by discussing the units shown on the plots (microradians), translating them into degrees, and drawing some example angles on the board. Could include the use of the (relatively static) plot on the Kilauea update page to further illustrate the second animation of the time lag of deformation between Kilauea Summit and Pu'u 'Ō'ō, if it shows a DI event at that point in time, or use the following saved image:

Delay of Tilt

Demonstrate the use of the VALVE interface by recreating the example graph at the bottom of The Tilt Page in the classroom, show how to use the cursor to select a time window within a time series graph to "zoom in".

The homework exercise will incorporate the following questions/assignments:

  • recreate the tilt + rain time series for the example DI event using the VALVE interface (detailed written instructions will be provided, in addition to the notes students should have made during the classroom demonstration, or a Jing-based tutorial might be available from the VEPP website itself)
  • create a similar time series plot for station POO further away from Pu'u 'Ō'ō
  • select only the time period of deflation within this time series and create a vector map for this period showing the tilt for both stations
  • do the same thing for the time period of inflation
  • print out the two maps and draw the location of the Pu'u 'Ō'ō crater on them, based on the map on the The Tilt Page
  • explain the map and the two vectors: do these vectors make sense, both in terms of direction as well as relative length, given the physical process involved (as shown in the inflation/deflation animations in class)?
  • by changing the time period covered by the time series (refer back to classroom demonstration or tutorial on how to change start and end time using interface), investigate a much larger time period and locate at least one other reliable (check the rainfall!) DI event
  • create a tilt + rain time series plot for both tiltmeters for this other DI event, choosing a time scale that will clearly show the entire event, similar to the original plot. Describe why this should be considered a reliable DI event, based on the rain data and a comparison with the original DI event data series.
  • compare and or contrast this DI event in duration and size with the previous event: did it last longer or shorter, was the tilt greater or smaller? Include actual measurements (including units) of both duration as well as size.
  • generate a similar time series plot of tilt and rain for the past week
  • based on the observations of the two DI events, interpret this final graph: is Pu'u 'Ō'ō currently experiencing a DI event? Why (not)?

Lecture material on tilt meters and Pu'u 'Ō'ō should be prepared, using the VEPP website, in particular The Tilt Page and Inflation-Deflation Example.

Teaching Notes and Tips

Accessing the VEPP Web site ( - website is down but a sample can be seen at 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:

Depending on time and level of interest, other datasets from VALVE, such as seismic amplitudes and GPS, may be incorporated in this exercise as well.

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

The instructor should examine the recent data from the VEPP Web site before attempting this exercise, to make sure there are no unexpected issues with this data that would make interpretation by students difficult.


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

The homework exercise will be graded. Feedback will be encouraged through the use of informal mid-quarter class evaluation forms.

References and Resources

VEPP: Analysis of Inflation-Deflation Events at Pu'u 'ÅŒ'ō Using Tiltmeter Data -- Discussion  

This post was edited by Phuoc Huynh on Nov, 2016
why is not available?


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