Abstract
The martian volcano Alba Patera is surrounded by a system of graben
which appears to be the result of an extensional stress applied to
the region after the construction of the volcano. These faults provide
a map of the stress field that created them. We used this information,
as well as the recent Goddard spherical harmonic gravity model (GMM-1)
and a spherical harmonic representation of the Mars Digital Elevation
Model, to constrain models of: (1) the lithospheric flexure under
the load of the volcano, (2) the gravitational anomaly due to the
volcano, and (3) the magnitude of the extensional stress in the region.
We found that elastic lithospheric thicknesses between 10 and 50
km resulted in statistically acceptable fits to the gravity and topography
data. We also found that a 1.5-2 kilobar extensional regional stress
in conjunction with the axisymmetric stress field of the volcanic
load produced a stress field that is consistent with the observed
trends of the graben. (C) 1997 Academic Press.
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