Displacement patterns of strike-slip faults in Malaysia-Indonesia-Philippines

Abstract

Detailed field studies seven important strike-slip faults in East and West Malaysia, West Sumatra, Java, and Central Sulawesi, used reliable, minor fault-plane markings (bruised step riser, spall, crescentic gouge, lunate fracture, chatter mark, pluck mark, slickenside prod mark) to determine the sense of displacement. The sense of movement on about ten other major transcurrent faults in the region was derived from the literature. A common direction of horizontal compression for each of three tectonic domains that subdivide the region between the Asian and Australian continents is indicated by consistent displacements along the wrench faults. For two of the currently active tectonic domains the directions of regional compression are 10°-190° (for Sumatra and Java) and approximately east-west (for the Philippines and the Indonesian islands east of Strait Makassar). These directions of regional compressions are parallel to compressive stress directions computed from sea-floor spreading rates by Le Pichon (1968) and to earthquake-slip vectors interpreted by Isacks et al. (1968) for the margins of the region under discussion.