What is the Volume of the 1992 Eruption of Cerro Negro Volcano, Nicaragua?

Ali Furmall (now at U Oregon) for Chuck Connor - University of South Florida, Tampa
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This material is replicated on a number of sites as part of the SERC Pedagogic Service Project


In this Spreadsheets Across the Curriculum activity, students are asked to calculate the volume of the 1992 eruption of Cerro Negro volcano, Nicaragua. An exponential thinning model is used to estimate the change in deposit thickness with distance from the vent. This is a self-paced activity in which students follow a PowerPoint presentation to create spreadsheets and graphs using Excel.

Used this activity? Share your experiences and modifications

Learning Goals

Students will:
  • Gain experience in making estimations from limited data sets using an exponential thinning model.
  • Make use of unit conversions involving meters.
  • Find a best-fit linear model of the data.
  • Estimate parameters (slope and y-intercept) from the best-fit linear model.
  • Develop a spreadsheet to carry out a calculation.
  • Be introduced to the Volcano Explosivity Index.
In the process the students will:
  • Begin to see the value of calculations based on approximate estimations.
  • Increase their skill at unit conversions.
  • Distinguish conceptually between areas and volumes.
  • Apply the concept of exponential decay to a physical model.

Context for Use

Equipment: Each student or pair of students needs a computer with Excel and PowerPoint.

Classes: This module has been used in an Introductory Physical Volcanology course with upper level undergraduates.

In the class, the module was introduced during lab to be completed as homework due the following week. Students turned in hard-copies of the Excel spreadsheets and graphs, as well as their working Excel files. This worked well for junior and senior level students with excellent quantitative skills.

Description and Teaching Materials

Powerpoint ssac-pv2007.qe522.cc2.8-student (PowerPoint 4.3MB Dec19 07)

If the embedded spreadsheets are not visible, save the PowerPoint file to disk and open it from there.

This PowerPoint file is the student version of the module. An instructor version is available by request. The instructor version includes the completed spreadsheet. Send your request to Len Vacher (vacher@usf.edu) by filling out and submitting the Instructor Module Request Form.

Teaching Notes and Tips

This module, like the others in this collection, works best if coordinated with lecture and lab material.

If students have difficulty in getting their equations to produce the correct numbers in the orange cells -- especially if their results are off by orders of magnitude -- tell them to check their unit conversions. You cannot ever emphasize unit conversions enough.

Some students jump ahead to the end-of-module assignments without working through the main part of the module carefully. Those students have trouble.


The end-of-module questions can be used for assessment.

The instructor version contains a pre-test

References and Resources

Pyle, D., 1989, The thickness, volume, and grainsize of tephrafall deposits, Bulletin of Volcanology, 51: 1-15.

Fierstein, J., and M. Nathenson, 1993, Another look at the calculation of tephra fallout volumes, Bulletin of Volcanology, 56: 121-132.

Bonadonna, C., and B. F. Houghton, 2005, Total grainsize distribution and volume of tephra fallout deposits, Bulletin of Volcanology 67: 441-456.

Connor, L.J., and C.B. Connor, 2006, Inversion is the solution to dispersion: understanding eruption dynamics by inverting tephra fallout, In:Mader, H.M., Coles, S.G., Connor, C.B., and Connor, L.J. (editors) Statistics in Volcanology, Special Publications of IAVCEI 1, Geological Society, London, 231-242.