12.9 Geological Interpretation

12.9 Geological Interpretation

The applicability of remote sensing data increases according to the improvement in the spatial resolution as well as the spectral resolution , for example as from Landsat MSS to Landsat TM and SPOT HRV.

The advantage of satellite remote sensing in its application to geology is the wide coverage over the area of interest, where much useful information such as structural patterns and spectral features can be extracted from the imagery.

There are two ways of information extraction; geometric feature extraction with the use of geomorphologic patterns and radiometric feature extraction using the unique characteristics of spectral absorption corresponding to the rock type.

Generally visual image interpretation is most widely used in order to extract geological information from remote sensing images.

A comprehensive analysis can be carried out with geomorphologic information such as land form and slope, drainage pattern and density, and land cover.

Figure 12.9.1 shows a Landsat TM image of the oil deposit basin in California, USA. Figure 12.9.2 shows the tectonic analysis of the same basin.

Radiometric interpretation of multi-spectral features is mainly applied to rock type classification.

Figure 12.9.3 shows a color composite of bands 4, 5 and 7 of Landsat TM in Gold Field Nevada, USA, in which the light green color shows the hydrothemal zones. Because each rock has its own spectral absorption band in the region of the short wave infrared, data from multi-spectral scanners or imaging spectrometers with multi channels is very useful for rock type classification. Thus the OPS data of JERS-1 will be useful in geology because of the shortwave infrared bands.