Abstract: LANDSAT Imagery: Evolving Exploration Tool for Geologists

Richard M. Zoerb

Since becoming available about 4 years ago, LANDSAT imagery has gained wide acceptance as a tool for resources-problem solving on a regional scale. Users include specialists in agriculture, forestry, wildlife management, and public health. Successful applications range from water-quality and other environmental-monitoring programs to geologic mapping for mineral deposits. The data serve the needs of government agencies as well as academic institutions and industry.

Typical end-use displays of LANDSAT images bear a strong resemblance to very high altitude airphotos. However, this format obscures the fact that basic LANDSAT data are in a digital mode, and that they therefore have much in common with source material used in applied geophysics. LANDSAT images represent variations in the intensity of visible and nonvisible light reflected from the surface of the earth, just as seismically derived data represent acoustic energy reflected from the earth's interior. In both cases great volumes of data are recorded digitally and stored on magnetic tape. Although sources of energy differ in terms of their velocity, frequency range, and wave length, data from both can be operated upon by standard seismic analysis and filtering techniques. Statistical metho s used in seismic processing have proved helpful in enhancing LANDSAT results, particularly in tailoring output to the needs of the exploration geologist.

A review of satellite-related systems acquaints the earth scientist with existing methods of data acquisition and with types of hard copy which currently are available to him. Examples of LANDSAT imagery include areas in North America, Central America, Europe, and Africa. Comparisons are made of the content of the four available spectral bands, and of the effects of filtering for purposes of image enhancement. Potential use to the exploration geologist is further illustrated with false color and density slice/contrast stretch displays based on refinement of data obtained directly from magnetic tapes.

AAPG Search and Discovery Article #90971©1976 AAPG-SEPM Rocky Mountain Sections 25th Annual Meeting, Billings, Montana