Tephra Dispersion Simulation Tool

Tephra2 is a tephra dispersion simulation tool, used to compare deposits to the eruption energetics that produced them. Tephra2 can be used to estimate the expected thickness and particle size distribution of pyrolastic ejecta from ancient lunar eruptions, and to model the dynamics of these eruptions.

Tephra2

Some background on the numerical modeling of tephra dispersion: PDF file (16MB)

Tephra2 is a tephra dispersion model that calculates the expected accumulation of tephra at a point(s), given explosive eruption conditions

The code simplifies the eruption conditions, calculating the expected tephra accumulation for a given total eruption mass, eruption column height, and particle size distribution

For terrestrial analogs, wind velocity varies as a function of height. Wind velocity is constant within a given stratum. Wind velocities as a function of height are sampled from the NOAA REANALYSIS database for the volcano

Tephra2 creates a isomass map, the expected accumulation over a region.

Inputs

Tephra2 takes the following inputs:

Volcanic vent location. Choose the volcano from the pull down menu. Currently these are terrestrial analogs.

Eruption mass. Specify the total mass of pyroclastic ejecta (kg)

Plume height (m)

Set alpha and beta, parameters in a Beta distribution which control the eruption column shape, which is strongly dependent on initial volatile content.

Set the total particle size distribution of the pyroclastic ejecta, assuming a lognormal distribution. Set minimum, maximum, mean (median) and standard deviation.

Set particle diffusion constants to account for particle-particle interaction and turbulence (both in the eruption plume and in the atmsophere for analogous eruptions).

Set particle densities.

Outputs

Tephra2 outputs:

An isomass map of the deposit (mass loading as a function of location)

You can choose to save the png image of the graph by right clicking on the graph

You can download various files used to create the graph, and numerical results

To Do

Specify alternative gravity fields and settling velocity models as part of user input (this already is possible in the code by modifying an existing data structure)

Allow for simulation using lunar volcano vent locations and DEMs

Create plots of the output of particle size distribution at specific locations (this output is already available as a data file)

References

Get the source code: Tephra2 on GitHub

Bonadonna, C., Connor, C. B., Houghton, B. F., Connor, L., Byrne, M., Laing, A., and Hincks, T. K. (2005). Probabilistic modeling of tephra dispersal: Hazard assessment of a multiphase rhyolitic eruption at Tarawera, New Zealand. Journal of Geophysical Research: Solid Earth, 110(B3).

Connor, Laura J., and Charles B. Connor. "Inversion is the key to dispersion: understanding eruption dynamics by inverting tephra fallout." (2006): Statistica in Volcanology, Geological Society of London Special Publications, 231.