Walanae Fault Kinematic Deduced from Geometric Geodetic GNSS GPS Monitoring

Dina Anggreni Sarsito,Alfend Rudyawan,Dhota Pradipta,Norman Arif Muhammad,Heri Andreas,Susilo Susilo,D.D Wijaya

doi:10.1051/e3sconf/20199404008

Dina Anggreni Sarsito, Alfend Rudyawan + Show 5 more

Open Access

https://doi.org/10.1051/e3sconf/20199404008

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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.

Highlights

The region of Eastern Indonesia is known to be an active tectonic region with high seismic activity which often has a negative impact in the form of material losses up to the loss of life after earthquakes hit the area
From the distribution of observation stations, it can be seen that CMAK, UJPD and CPRE located in the western part of West Walanae Fault, have almost the same rate pattern (25.800 ± 0.24; -6.660 ± 0.18) mm / year, (24.720 ± 1.07; -7.630 ± 0.54) mm / year and (24.020 ± 0.17; -7.090 ± 0.29) mm / year where this indicates that the three stations are in the same region
Stations located in the western part of the South Arm, namely CMAK, UJPD and CPRE have velocity rate (1.815 ± 0.24; 5.037 ± 0.18) mm / year, (0.708 ± 1.07; 4.107 ± 0.54) mm / year and (-0.332 ± 0.17 ; 4.676 ± 0.29) mm / year shows a slight decrease in absolute rate from 5.354 mm / year in the southern part to 4.678 mm / year in the northern part

Summary

Introduction

The region of Eastern Indonesia is known to be an active tectonic region with high seismic activity which often has a negative impact in the form of material losses up to the loss of life after earthquakes hit the area. Sulawesi Island, which is located in this location, is in the western boundary between Eastern Indonesia and Sunda Blok which is relatively stable compare to the eastern area This island is a result of triple junction convergence phenomena between Eurasian Continental-Sunda Block, Indo-Australian Plate and Pacific Ocean Plate, that creates several major faults across the island. In the southern part of this region, namely the South Sulawesi Arm zone, there is a fault which is defined as a central wrench with a Northwest-Southeast direction that divides the South Arm of Sulawesi. The fault system kinematics have been studied geologically by [11, 12, 13, 14] but has never been done in the details of the geodetic method. The validation of the geodetic results are from geological studies that have been carried out by previous researchers

Data and Method

Result and Discussion

Conclusion