FAULT-STRIAE ANALYSIS - A TURBO PASCAL PROGRAM PACKAGE FOR GRAPHICAL PRESENTATION AND REDUCED STRESS TENSOR CALCULATION

We describe integrated computer programs for graphical presentation, on-screen selection, and reduced stress tensor calculation of fault-striae data. The input consists of dip azimuth and dip inclination of faults, bearing and plunge of associated striae, relative slip-sense of the hanging wall, and degree of confidence in the slip-sense determination. The data are checked for inaccurate measurements, if necessary corrected (program CHECK), and represented on the equal area, lower hemisphere stereonet either as fault poles (program F-SH) or as great circles (program F-S). In both situations. arrows point in the direction of relative hanging-wall slip; their heads express the confidence levels in slip-sense determination. Program ORIENT plots dip azimuth and dip inclination of faults, striae bearing and plunge, and rake as rose diagrams, enabling a quick recognition of the dominant fault types. Program TURNER determines the best-fitting contraction and extension axes (P-B-T axes method) for each fault striae data set. Program INVERS calculates the principal stress directions and the stress ratio according to the direct inversion method. The angle between the calculated direction of maximum shear stress along the fault plane and the measured striae is determined for each data set, and the distribution of these angles is plotted in a histogram. The relative values of normal and shear stresses are plotted in a normalized Mohr circle diagram. Graphical output is in standard HPGL files, suitable for publication-quality plotting by commercial word-processing and graphics programs. Data handling by the program package is demonstrated with a test file. Finally, the output of our programs is compared with that provided by published routines implementing different techniques.