Walanae Fault Kinematic Deduced from Geometric Geodetic GNSS GPS Monitoring

Abstract

The western Sulawesi region has the main structural boundary, the Palu Koro Fault which divides from Palu Bay at the northest part to Central Sulawesi and continues into the Bone Gulf in southest part. In the southern part of this region, namely the South Sulawesi Arm zone, there is a Walanae fault which is defined as a sinistral wrench with a NW-SE direction that divides the South Arm of Sulawesi. This fault in the northern part is expected to continue to the northwest intersecting the Makassar Strait and unite with Paternoster-Lupar (Kalimantan) sutures and at the southest ending in Flores thrust fault. Walanae fault system did not only have one strand but was divided into 4 parts, namely the northern East Walanae Fault with a slip rate of 6.634 mm/year and the southern part with a 7.097 mm/year of slip rate, as well as the northern part of West Walanae Fault with a slip rate of 4.528 mm/year and the southern part with a slip rate of 3.270 mm/year. The northern part of Walanae fault system has opening or spreading pattern occurs that is in harmony with the formation of Walanae depression. By using simple geometric modeling, we found the fault system have 2 strain partitions with dominant sinistral strike slip pattern at southern part and combination between left lateral strike slip with thrust fault pattern at northern part.