Pengaruh Variasi Peak Ground Acceleration (PGA) dan Magnitudo terhadap Potensi Likuifaksi (Studi Kasus: Kota Palu)

Abstract

Kota Palu merupakan wilayah yang rentan terhadap likuifaksi akibat dominasi endapan aluvial muda dan aktivitas seismik yang tinggi. Penelitian ini bertujuan menentukan tingkat potensi likuifaksi, menganalisis pengaruh variasi Peak Ground Acceleration (PGA) dan magnitudo terhadap potensi likuifaksi, serta menyusun peta zonasi potensi likuifaksi. Analisis dilakukan menggunakan metode Idriss dan Boulanger (2010) berdasarkan 25 data borehole dengan variasi PGA 0,6; 1,2; 1,5; dan 2,0 g serta magnitudo 5,0; 6,6; 7,4; dan 9,1 Mw. Potensi likuifaksi dievaluasi menggunakan Liquefaction Potential Index (LPI) dan dipetakan melalui metode Inverse Distance Weighted (IDW). Hasil validasi menunjukkan sebagian besar wilayah terdampak Gempa Palu 2018 berada pada kategori LPI sangat tinggi (LPI > 15). Peningkatan PGA meningkatkan potensi likuifaksi secara signifikan, terutama pada rentang 0,6–1,2 g, sedangkan pengaruh magnitudo relatif lebih kecil. Analisis spasial menunjukkan sebagian besar wilayah penelitian didominasi kategori LPI sangat tinggi. Hasil penelitian menunjukkan bahwa PGA merupakan faktor dominan yang mengontrol potensi likuifaksi di Kota Palu.

Palu City is an area susceptible to liquefaction due to the dominance of young alluvial deposits and high seismic activity. This study aims to determine the level of liquefaction potential, analyze the influence of Peak Ground Acceleration (PGA) and magnitude variations on liquefaction potential, and compile a liquefaction potential zoning map. The analysis was conducted using the Idriss and Boulanger (2010) method based on 25 borehole data with PGA variations of 0.6; 1.2; 1.5; and 2.0 g and magnitudes of 5.0; 6.6; 7.4; and 9.1 Mw. Liquefaction potential was evaluated using the Liquefaction Potential Index (LPI) and mapped using the Inverse Distance Weighted (IDW) method. The validation results show that most of the areas affected by the 2018 Palu Earthquake are in the very high LPI category (LPI > 15). Increasing PGA significantly increases liquefaction potential, especially in the 0.6–1.2 g range, while the magnitude effect is relatively smaller. Spatial analysis shows that most of the study area is dominated by the very high LPI category. The results indicate that PGA is the dominant factor controlling liquefaction potential in Palu City.