Geomorphic indices like stream length gradient index (SL), mountain front sinuosity (Smf) and ratio of valley floor
width to valley height (Vf) have previously been used to detect active tectonic features from observations of first order
rivers and regional fault systems in areas where accurate topographic maps were available. However, areas in equatorial
South East Asia present many problems, being remote, covered by dense forest and lacking full, detailed topographic
surveys. Here a new approach is attempted, using results coming from the comparison of SRTM derived DEM's
(SRTM-DEM) to traditional topographic 1:50,000 survey derived DEM's (TS-DEM).
Neo-tectonic activity on the Palu-Koro fault in West Sulawesi was assessed using geomorphic indices calculated for
major river systems (3rd up to 7th strahler order) derived from
Mountain front sinuosity indices are similar whether derived from SRTM-DEM or TS-DEM. Likewise, although the
ranges differ, valley floor width to valley height ratios returns the same average value. The stream length index was
influenced by systematic sensor errors in areas of extreme local relief on SRTM-DEM.
A visual classification of river deflections and water gaps was performed in order to identify the best locations for wider
application of geomorphic indices on the SRTM-DEM. While geomorphic calculations on SRTM-DEM's break down
for flood plain valleys, yielding erroneous results, geomorphic indices may be successfully used to identify secondary
fault systems in other parts of West Sulawesi.