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

We describe integrated computer programs for graphical presentation, o n-screen selection, and reduced stress tensor calculation of fault-str iae data. The input consists of dip azimuth and dip inclination of fau lts, bearing and plunge of associated striae, relative slip-sense of t he hanging wall, and degree of confidence in the slip-sense determinat ion. The data are checked for inaccurate measurements, if necessary co rrected (program CHECK), and represented on the equal area, lower hemi sphere stereonet either as fault poles (program F-SH) or as great circ les (program F-S). In both situations. arrows point in the direction o f relative hanging-wall slip; their heads express the confidence level s in slip-sense determination. Program ORIENT plots dip azimuth and di p inclination of faults, striae bearing and plunge, and rake as rose d iagrams, enabling a quick recognition of the dominant fault types. Pro gram TURNER determines the best-fitting contraction and extension axes (P-B-T axes method) for each fault striae data set. Program INVERS ca lculates the principal stress directions and the stress ratio accordin g to the direct inversion method. The angle between the calculated dir ection 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 sh ear stresses are plotted in a normalized Mohr circle diagram. Graphica l output is in standard HPGL files, suitable for publication-quality p lotting by commercial word-processing and graphics programs. Data hand ling by the program package is demonstrated with a test file. Finally, the output of our programs is compared with that provided by publishe d routines implementing different techniques.