Abstract: Satellite Exploration by Geophysicists

Richard M. Zoerb

Since becoming available 4 years ago, LANDSAT imagery has gained wide acceptance as a tool for resource-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 environment-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 gathered in a digital mode, and that they therefore have much in common with the source material of 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, great volumes of information 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 respond to standard seismic analysis and filtering techniques. Statistical methods sed in seismic processing have proved helpful in enhancing LANDSAT images, particularly in tailoring output to fulfill the needs of specific operational or research programs.

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. Examples of LANDSAT imagery in North America, Central America, Europe, and Africa illustrate the content of the four available spectral bands and the effects of filtering for purposes of image enhancement. The geophysicists can make further contributions with false color and density-slice/contrast stretch displays based on in-house processing of magnetic tapes.

AAPG Search and Discovery Article #90976©1976 AAPG-SEPM-SEG Pacific Section Meeting, San Francisco, California