Previous studies of fluidized ejecta blankets (FEB) around Martian craters assumed the model of hydrodynamic outflow of ejecta after deposition. We now use the Bingham rheology as a means to compare mass motions of various types. Bingham parameters (cohesion and viscosity) for the FEB material should be smaller than similar parameters for terrestrial dry rock avalanches but larger than for typical Bingham parameters. In the present paper we attempt to move toward a quantitative interpretation. The current model treats the FEB material as a mixture of volatile-rich material (VRM) and dry rock debris. Comparing the modeled ejecta runout with observations indicates that the ratio of the outer FEB radius to the crater radius, Rm/Rr, would increase even for constant VRM percentage due to the scale effect; the Rm/Rr ratio is sensitive to the flow geometry, so that radially divergent flow stops earlier than a quasiparallel flow. Radial inhomogenity of the flow field may be responsible for the lobateness of the FEBs.
Lunar and Planetary Science Conference
- Pub Date:
- March 1997
- Mars Surface;
- Lunar and Planetary Exploration;
- EJECTA BLANKETS: FLUIDIZED;
- WATER: MARTIAN