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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
E06S04,
doi:10.1029/2005JE002589,
2006
Ground-penetrating radar sounding in mafic lava flows: Assessing attenuation and scattering losses in Mars-analog volcanic
terrains
Essam Heggy
Lunar and Planetary Institute, Houston, Texas, USA
Stephen M. Clifford
Lunar and Planetary Institute, Houston, Texas, USA
Robert E. Grimm
Department of Space Studies, Southwest Research Institute®, Boulder, Colorado, USA
Cynthia L. Dinwiddie
Department of Earth, Material, and Planetary Sciences, Southwest Research Institute®, San Antonio, Texas, USA
Danielle Y. Wyrick
Department of Earth, Material, and Planetary Sciences, Southwest Research Institute®, San Antonio, Texas, USA
Brittain E. Hill
Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute®, San Antonio, Texas, USA
Abstract
We conducted low-frequency (16 to 100 MHz) ground-penetrating radar surveys on the eroded lava flows at Craters of the Moon
(Idaho, USA) volcanic field to evaluate the potential of future radar-sounding investigations on Mars to map shallow subsurface
features. Radar-sounding profiles were obtained from three locations: above a lava tube, across a volcanic rift, and over
a scoria cone. Results were combined with laboratory permittivity and magnetic permeability measurements of field-collected
samples to deconvolve the electromagnetic attenuation and scattering losses from the total losses and therefore separately
quantify both effects on the radar penetration depth. Our results demonstrate a constrained performance for low-frequency
sounding radars to characterize mafic, arid volcanic terrains that contain a significant amount of ferro-oxides (∼14%), mainly
in the form of olivine and magnetite. Penetration depths of 35 m were achieved at a frequency of 100 MHz, and depths of 80
m were achieved at 16 MHz, with an effective dynamic range of 60 dB. Results indicate that for frequencies below 100 MHz,
the electromagnetic attenuation dominated the signal losses while above this frequency threshold the volume scattering dominated
the losses. Over our frequency range, the observed electromagnetic attenuation and penetration depths were strongly dependent
on the magnetic losses, ground porosities, and degree of heterogeneity rather than the sounding frequency. In light of these
results, we suggest average attenuation and scattering losses measured in terms of dB/m and discuss the expected penetration
depth for the Mars orbital radar-sounding instruments SHARAD and MARSIS in mafic volcanic terrains.
Received 3
September
2005;
accepted 10
March
2006;
published 29
June
2006.
Keywords: ground-penetrating radar;
subsurface;
Mars.
Index Terms: 0994 Exploration Geophysics: Instruments and techniques; 0925 Exploration Geophysics: Magnetic and electrical methods (5109); 5194 Physical Properties of Rocks: Instruments and techniques; 6225 Planetary Sciences: Solar System Objects: Mars.
Read Full Article (file size: 7359289 bytes) Cited by
Citation: Heggy, E., S. M. Clifford, R. E. Grimm, C. L. Dinwiddie, D. Y. Wyrick, and B. E. Hill
(2006),
Ground-penetrating radar sounding in mafic lava flows: Assessing attenuation and scattering losses in Mars-analog volcanic
terrains,
J. Geophys. Res.,
111,
E06S04,
doi:10.1029/2005JE002589.
Copyright 2006 by the American Geophysical Union.
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