Methodology for Computer-aided, Interactive Rapid Assessment of Local or Regional Stress Fields

Introduction: On Earth, crustal deformation such as faulting, fracturing, and folding strongly influences surface topography, distribution and exposure of rock units, flow and accumulation of surface water, flow and entrapment of subsurface fluids (such as groundwater , oil, and natural gas), ore mineralization, climate conditions, heat flow in the crust, and seismicity. For a wide range of purposes and processes, understanding deformation features at or near the Earth's surface has been instrumental in exploring for natural resources, and for understanding the evolution of the Earth's crust and its relationship with the hydrosphere, atmosphere and mantle. Based on the many similarities between Earth and Mars, Mars deformation processes and features and the variability of resolved stresses on deformation features have a profound influence on fluid movement, related surface and subsurface mineraliza-tion, and the potential for past and present existence of life on Mars. Deformation features on Mars, including normal faults and resulting grabens, contractional wrinkle ridges, extension fracture systems, and relatively rare strike-slip faults have been mapped in local areas of investigation and in some cases, deformation features have been analyzed in detail [1-8]. These investigations have concentrated on mechanics or statistics of particular deformation features, or on details of deformation mechanisms compared with similar features on Earth. Only a few studies focus on the larger-scale structural evolution of the crust of Mars [1,2]. In the present investigation, we focus on a range of scales, from regional patterns of deformation to the details of fault morphology, including corrugations, linkages, and interactions of faults. We have developed a methodology for detailed mapping of large-scale structural features on Mars, determination of stress orientations responsible for deformation, and analysis of resolved stresses along such structures. We present preliminary results for northern Utopia Planitia on Mars to demonstrate our approach. Methodology: We used Mars Orbiter Laser Al-timeter (MOLA) data as the basis for interpreting deformation features on Mars. MOLA data come from two sources and include (i) Mission Experiment Grid-ded Data Record (MEGDR), the publicly available digital terrain models at 1/64th degree pixels and 1/128th degree pixels; and (ii) Precision Experiment Data Record (PEDR), data organized along satellite orbital tracks. We prepare digital terrain models by extracting PEDR data for our selected model area,