Lunar remote sensing and measurements

Moore, H. J.; Boyce, J. M.; Schaber, G. G.; Scott, D. H.

doi:10.3133/pp1046b

Cited by 18 publications

(5 citation statements)

References 71 publications

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“…However, the theology estimates should allow some general comparisons to be made •t•'•en lava flows on different planets. Rheologic estimates tuYe been calculated from flow dimensions for flows on Earth [Halroe, 1974;Moore et al, 1978], moon [Moore and Schaber, 1975;Hulrne and F•,lder, 1977;Moore et al, 1978]…”

Section: Introductionmentioning

confidence: 99%

Estimates of rheologic properties for flows on the Martian volcano Ascraeus Mons

Zimbelman

1985

J. Geophys. Res.

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Morphological measurements on six well‐defined volcanic flows near the summit of the Martian volcano Ascraeus Mons were used to calculate the yield strength and viscosity of the lavas. The yield strength estimates range from 3.3×104 to 8.3×104 Pa (N m−2), with an average value of 2.1×104. These values are similar to yield strengths calculated for other flows on Martian and terrestrial shield volcanoes, but they are an order of magnitude less than the value for terrestrial andesite flows and two orders of magnitude greater than values for lunar flood basalts. Lengths of the Ascraeus Mons flows indicate lower limits on the effusion rate of 18–60 m3 s−1, with an average value of 35. Effusion rate and yield strength are used to calculate upper limits on the lava viscosity of 6.4×105 to 2.1×108 Pa‐s, with an average value of 2.3×107 (equivalent to 2.3×108 poise). Ridges on one flow indicate a viscosity lower limit of 1.1×108 Pa‐s for a ridge growth time of one hour. The estimated rheologic properties of the Ascraeus Mons flows are most consistent with basaltic or basaltic andesite lavas, but some individual flows may consist of more highly evolved lavas.

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Section: Introductionmentioning

confidence: 99%

Estimates of rheologic properties for flows on the Martian volcano Ascraeus Mons

Zimbelman

1985

J. Geophys. Res.

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“…Finally, any strong dielectric boundary, such as between the soil and a rock basement, will make a contribution if the radar energy is not attenuated prior to encountering the bedrock interface. Imaging radar data for the Moon have often been used as a tool for characterizing the regolith, particularly in the study of crater ejecta distribution and large pyroclastic deposits [e.g., Zisk et al, 1977;Thompson et al, 1979;Moore et al, 1980;Gaddis et al, 1985]. Much of this work utilized the 3.8-cm radar maps of Zisk et aI.…”

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confidence: 99%

Regolith composition and structure in the lunar maria: Results of long‐wavelength radar studies

Campbell¹,

Hawke²,

Thompson³

1997

J. Geophys. Res.

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Abstract. Radar measurements at 70-cm and 7.5-m wavelengths provide insight into the structure and composition of the upper 5-100 m of the lunar regolith and crust. We combine highresolution (3-5 km) 70-cm radar data for the nearside with earlier calibrated full-disk observations at •e same wavelength to provide a reasonable estimate of the lunar backscatter coefficient. These ci'm are tested against models for echoes from a buried substrate and Mie scattering from surface .and buried rocks. These mechanisms are expected to dominate the 70-cm radar echo, with their relative importance determined by the rock population, regolith depth, substrate roughness, and the loss tangent of the soil. Results indicate that the 70-cm radar echo for the maria comes largely from Mie scattering by rocks buried within the fine soil. Radar scattering from a buried substrate is not likely to greatly affect the observed return. We also compared the 70-cm and 7.5-m radar images to infrared eclipse temperature maps, crater-population age estimates for the maria, and to Ti02 and FeO abundances inferred from Earth-based telescopic and Clementinc multispectral .•bservations. These data imply that (1) the TiO 2 (ilmenite) content of the regolith controls variations in 70-cm depo!arized echo strength among mare units, with higher titanium abundance leading to lower echoes; (2) changes in the average 70-cm return for a given TiO 2 abundance between maria of different ages do occur, but uncertainties in the current radar data do not allow us to uniquely distinguish between variations in rock population with age and calibration effects; (3) '.the 7.5-m radar echoes are controlled by the age of the mare basalt flows, with older deposits -having a greater degree of fracturing and higher backscatter. Future mapping at 12.6-cm and 70-cm wavelengths will help to resolve some of the issues raised here.

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“…The evolution of viscosity behaved in a decreasing way when Equations ( 2) and (3) were used, being slightly faster with Equation (3) than with Equation (2) (see dashed curves plotted for each result in Figure 5d). The results were acceptable when the lava flow did not develop lateral levees and its extension was considerably greater than its thickness [117]. This was the case of the first days we studied.…”

Section: Discussionmentioning

confidence: 73%

“…In practice, Jeffreys' expression, (1) or ( 2), is applied under laminar flow conditions, and when the lava flow sections have a width much larger than the depth or thickness of the flow [117] and assuming Newtonian behaviour of the fluid. Using one of the two, η 1 or η 2 gives an a priori estimate of the apparent viscosity [101] from depth-averaged measurements of the heterogeneous lava flow by taking an average thickness and velocity, an estimated value of its density, and the average slope of the terrain if it does not undergo major changes in relief.…”

Section: Inferring Lava Flow Rheologymentioning

confidence: 99%

Attempt to Model Lava Flow Faster Than Real Time: An Example of La Palma Using VolcFlow

2022

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The eruption of Cumbre Vieja (also known as Tajogaite volcano, 19 September–13 December 2021, Spain) is an example of successful emergency management. The lessons learnt are yet to be fully disclosed as is whether the response can be further improved. The latter may include tools to predict lava flow inundation rheological characteristics, amongst other issues related to volcanic eruptions (i.e., ash fall and gas emission). The aim of this study was to explore if a scientific open-source, readily available, lava-flow-modelling code (VolcFlow) would suffice for lava emplacement forecasting, focusing on the first seven days of the eruption. We only the open data that were released during the crisis and previously available data sets. The rheology of the lava, as well as the emission rate, are of utmost relevance when modelling lava flow, and these data were not readily available. Satellite lava extent analysis allowed us to preliminarily estimate its velocity, the average flow emitted, and flow viscosity. These estimates were numerically adjusted by maximising the Jaccard morphometric index and comparing the area flooded by the lava for a simulated seven-day advance with the real advance of the lava in the same timescale. The manual search for the solution to this optimization problem achieved morphometric matches of 85% and 60%. We obtained an estimated discharge rate of about 140 m3/s of lava flow during the first 24 h of the eruption. We found the emission rate then asymptotically decreased to 60 m3/s. Viscosity varied from 8 × 106 Pa s, or a yield strength of 42 × 103 Pa, in the first hours, to 4 × 107 Pa s and 35 × 103 Pa, respectively, during the remainder of the seven days. The simulations of the lava emplacement up to 27 September showed an acceptable distribution of lava thickness compared with the observations and an excellent geometrical fit. The calculations of the calibrated model required less time than the simulated time span; hence, flow modelling can be used for emergency management. However, both speed and accuracy can be improved with some extra developments and guidance on the data to be collected. Moreover, the available time for management, once the model is ready, quasi-linearly increases as the forecasting time is extended. This suggests that a predictive response during an emergency with similar characteristics is achievable, provided that an adequate rheological description of the lava is available.

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Lunar remote sensing and measurements

Cited by 18 publications

References 71 publications

Estimates of rheologic properties for flows on the Martian volcano Ascraeus Mons

Estimates of rheologic properties for flows on the Martian volcano Ascraeus Mons

Regolith composition and structure in the lunar maria: Results of long‐wavelength radar studies

Attempt to Model Lava Flow Faster Than Real Time: An Example of La Palma Using VolcFlow

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