FAULT-STRIATION PAIR ANALYSIS (F-SPA) Tool

FAULT-STRIATION PAIR ANALYSIS (F-SPA) is an easy-to-use tool to process and graph geological data, operating in MATLAB environment (www.mathworks.com). It performs kinematic analyses of fault-striation pairs (FSPs) from geological field data and from focal mechanisms. We developed the MATLAB© software package to make several calculations from slickensides and slickenlines in terms of sense of motion, kinematic classification and associated deformation pattern. In particular, this tool calculates the slip rake value (Aki & Richard format) starting from the fault-striation attitude or trend and plunge of the stria, from fault-rake data input. Moreover, it converts slip rake in pitch value, calculates the conjugate fault and slip vector orientation, the P T B deformation axes with a fracture angle θ of 45° and a variable angle θ (chosen by users). Finally, it plots these information in stereographic projections (Schmidt net). Three MATLAB scripts are provided: the .m file "strain_calc_from_striae.m" and the .m file "strain_calc_from_rake" to process the input geological datasets and return a text file (.txt) containing all calculated values, and a third .m file " Plot_stereonet” which processes the stereographic projection starting from the previous two. Input data (in a .txt file), must contain information on the attitude of the FSP in the first case, or information on the attitude of the fault with the relative slip rake value. The specific text formats are described and illustrated in the next sections of this guide. The purpose of this code is to have the greatest number of information obtainable from geological data using a single tool and to implement structural analysis in the fields of geology and seismology.