Empirical Attenuation Model for Predicting Peak Ground Acceleration in North Arm Sulawesi, Indonesia

The North Arm of Sulawesi is one of the areas that has very active tectonic conditions. The earthquake source in this area comes from the activity of several tectonic plates such as the North Sulawesi Subduction, the Molluca Sea Collision, the Philippine Sea Plate, the Pacific Plate and several local faults such as the Palu Koro Fault, Gorontalo Fault, Bolmong Fault and Manado Fault. The purpose of this study was to determine the peak ground acceleration value using several empirical attenuation models such as the Fukushima-Tanaka, Donovan, McGuire, Campbell, and Crouse. The peak ground acceleration is the value of the greatest acceleration a place has ever occurred which describes the strength of the tremor or shock of an earthquake. Geographically, this research area is located at 118⁰E to 127⁰E and 0.5⁰S to 4⁰N. The data used are data from the ISC-EHB and USGS catalog during the observation interval 1964-2020. Data processing includes the uniformity of the magnitude scale into the Surface Magnitude (Ms) scale, determining the main shock, sorting earthquake data with a magnitude greater than M6.0 and a depth of less than 100 km, creating a grid measuring 0.05 x 0.05 degree. Next step, determine the peak ground acceleration using an empirical attenuation relationships. The analysis results show that the peak ground acceleration in the North Arm Sulawesi is as follows: McGuire Method 0.4295g, Fukushima-Tanaka 0.3595g method, Crouse method 0.314g, Donovan method 0.3149g, and Campbell method 0.2550g.