How can a volcanic eruption's energy be Calculated?

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Discussion Overview

The discussion centers on methods for calculating the energy released during a volcanic eruption, exploring various approaches and formulas. Participants consider both theoretical and practical aspects of the calculations involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest using the increase in potential energy of the solid material that emerges, proposing the formula Ep=mgh, where mass can be estimated from the volume and density of the magma/lava.
  • Others mention that more refined calculations could include the mass of tephra in the plume and heat lost as the lava cools, although they suspect these factors may not significantly alter the order of magnitude of the energy estimate.
  • One participant references the Volcanic Explosive Index as a potential resource for understanding eruption energy calculations.
  • Another approach discussed involves calculating the volume of earth ejected from a crater using before and after images, making assumptions about density to derive mass and energy.
  • A later reply highlights a specific study that examines the energy required to lift a certain volume of rock to a specific height, suggesting it provides a definitive result.

Areas of Agreement / Disagreement

Participants express various methods for calculating volcanic eruption energy, but no consensus emerges on a single approach or formula. Multiple competing views and methods remain present in the discussion.

Contextual Notes

Some calculations depend on assumptions regarding density and the specific conditions of the eruption, which may vary significantly. The discussion does not resolve these uncertainties.

promeus
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The thread title speaks for itself,I am wondering how I would be able to this.

Ex:

Volcano A erupts

Volcano A yielded 1 kiloton of energy.

^^^How would I calculate that? ^^^
 
Last edited:
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promeus said:
The thread title speaks for itself,I am wondering how I would be able to this.

Ex:

Volcano A erupts

Volcano A yielded 1 kiloton of energy.

^^^How would I calculate that? ^^^

I have never seen the calculation worked out, but it seems like a good first approximation is to calculate the increase in potential energy of the solid material that emerges used Ep=mgh. You could estimate the mass of the magma/lava from its volume and density (which will vary with magma composition). The change in height would be from the magma chamber to the altitude at which it cools.

More refined calculations could take into the mass of tephra in the plume and the heat lost as the lava cools. I suspect those contributions will not change order of magnitude, and perhaps give the same value to one significant figure.
 
There is Volcanic Explosive Index - http://volcanoes.usgs.gov/images/pglossary/vei.php
http://en.wikipedia.org/wiki/Volcanic_Explosivity_Index


I believe that one option is to calculate the volume of Earth ejected from a crater (from before and after pictures) then some assumption of the density is made to calculate the mass and how it was ejected.

More recently - "Explosive Energy" During Volcanic Eruptions from Fractal Analysis of Pyroclasts
http://www.earth-prints.org/bitstream/2122/1820/1/subm revised to epsl_Kueppers et al_fractals.pdf
 
Astronuc said:
I believe that one option is to calculate the volume of Earth ejected from a crater (from before and after pictures) then some assumption of the density is made to calculate the mass and how it was ejected.

yes that's true
one other link I followed the other day was along those lines

they look at the energy required to lift say 10 cubic km of rock of "x" density to 510m


its gives a reasonably definitive result.

cheers
Dave
 

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