Spatial Patterns of Peak Ground Acceleration (PGA) Earthquake on Final Disposal Sites Plan in Samosir Regency

The strategic location of Samosir Regency, which located in the middle of Lake Toba and enriched with nature tourism, history and culture made tourism were a pre-eminent sector. However, there were several threats that can occur, the threat of earthquake and the waste problems that pollute Lake Toba due to the final disposal sites has not been made. This study aims to analyze the potential of earthquake risk to the development plan of Samosir Regency. The potential for earthquake risk is obtained by the calculation of Peak Ground Acceleration (PGA). The results showed the highest value of PGA was located at the western part of Samosir Regency and the value decreased as it came up to eastern. The highest PGA value is 237,36 SR and the lowest PGA value is 115, 91 gals with range VII to VIII MMI scale. Spatial patterns of low population density were in high PGA areas and otherwise. Based on 250 m buffer analysis on both sides of Semangko Fault, the three planned final disposal sites location (Batu Napal, Simpang PT EJS and Pamittoran) were located outside the active fault zone but these sites located in earthquake prone areas.