MOLASSES - PDC

MOLASSES - PDC - At a Glance

MOLASSES stands for MOdular LAva Simulation Software for the Earth Sciences. Initially, MOLASSES began as a cellular automata algorithm to estimate the area inundated by lava flows. MOLASSES does not model the rate of emplacement or the physical dynamics of flows. Here, the code is being extended to forecast the emplacement of pdcs. A digital elevation model (DEM) of the impacted region is pre-loaded on the server; flows are simulated using this DEM. Flow thickness

Inputs

MOLASSES - PDC expects the following inputs:

• pdc source location -- Location is specified as an easting and northing in UTM coordinates.
• modal thickness -- Complete thickness of the flow package including gas (90%) + suspended pyroclastic fragments (10%).
  Deposit Thickness:
  For very thin beds: .01 – .03 (m) use a modal thickness of .1 - .3 (m)
  For thin beds: .03 – .1 (m) use a modal thickness of .3 - 1 (m)
  For medium beds: .1 – .3 (m) use a modal thickness of 1 - 3 (m)
  For thick beds: .3 – 1 (m) use a modal thickness of 3 - 10 (m)
  For very thick beds: >1 (m) use a modal thickness of > 10 (m)
  The code distributes accumulations from cell to cell. Flows will pool or thicken in low lying areas and will thin at the flow margins.
• flow volume -- Typical pdc values range from 1e6 (1,000,000) cubic meters to 1e10 cubic meters; 1e9 corresponds to one cubic kilometer. MOLASSES continues to execute until this total volume of lava is erupted on to the DEM.
• flow pulse volume -- This volume is a fraction of the total flow volume and represents pulses. A volume is pulsed from the vent cell and spreads over the topograpy until exhausted. Relatively small pulse volumes tend to make the flow follow the topography more closely; large pulse volumes allow the flow to surmount topographic obstacles.
• Digital Elevation Model (DEM) -- MOLASSES can read in any DEM that is readable by gdal routines. Currently, users can only use DEMs stored in the server DEM library. Should you have a DEM that would be a good addition to our DEM library, please contact Laura Connor or Chuck Connor

Outputs

MOLASSES produces the following outputs:

• A map, PNG file (flow0.png), showing the area inundated by the flow on a shaded relief DEM -- You can choose to save the PNG image by right-clicking on the map and selecting an appropriate option. Vent location is indicated by a white circle on the map; the flow will be in shades of gray, darker shades indicative of increasing thickness.
• A text file (flow0) of flow locations in UTM coordinates and flow thickness in meters
  (file format:)
  (first line) easting northing volume pulse modal-thickness
  (...) easting northing thickness new_elevation original_elevation

Note the [Choose a file to download] button. You can select any of the input, output, or log files created by the tool and view or download them. The log files are useful if no flow appears on the map or no map is produced. An error situation occurs if the flow source is selected outside of the map area or if the flow reaches the boundary of the map area. Check the log files if either of these situations are suspected.

Run a MOLASSES Model

Run MOLASSES » Run MOLASSES(PDC) » Run MOLASSES(AVF) » Run LavaC »

References

• The MOLASSES source code can be downloaded from GitHub
• Original application of the proto-(perl)version of MOLASSES:
  Connor, L. J., Connor, C. B., Meliksetian, K., & Savov, I. (2012) Probabilistic approach to modeling lava flow inundation: a lava flow hazard assessment for a nuclear facility in Armenia. Journal of Applied Volcanology (1):3. DOI 10.1186/2191-5040-1-3
• Comparison of MOLASSES output for an actual lava flow:
  Kubanek, J., Richardson, J. A., Charbonnier, S. J., & Connor, L. J. (2015) Lava flow mapping and volume calculations for the 2012–2013 Tolbachik, Kamchatka, fissure eruption using bistatic TanDEM-X InSAR. Bulletin of Volcanology 77(12):106. DOI 10.1007/s00445-015-0989-9
• Benchmarking MOLASSES and similar codes:
  Dietterich, H. R., Lev, E., Chen, J., Richardson, J. A., & Cashman, K. V. (2017) Benchmarking computational fluid dynamics models of lava flow simulation for hazard assessment, forecasting, and risk management. Journal of Applied Volcanology 6(1):9. DOI 10.1186/s13617-017-0061-x

The development of MOLASSES was partially funded by a grant from the US National Science Foundation.