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Estimation of Seismic Ground Motion Induced by the 23 January, 2005 Earthquake in Palu Region, Central Sulawesi, Indonesia




Author(s)

Pyi Soe Thein, Subagyo Pramumijoyo, Kirbani Sri Brotopuspito, Junji Kiyono, Wahyu Wilopo, Aiko Furukawa and Agung Setianto

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DOI:10.17265/2328-2193/2014.04.002

On January 23rd 2005, a strong earthquake with moment magnitude (Mw 6.3) hit the Palu City (Central Sulawesi area). The earthquake involved an area more than 800 km along the Palu Koro fault zone. In order to characterize the seismic ground motion of alluvium layers existing in the Palu City, eight sites of microtremor array measurements were performed. The shear wave velocity of the top layer is ≤ 300 m/s. Palu City had deposited on a thick alluvial layer in the coastal area. The subsurface geology also changes slowly from soft sedimentary layers in the coastal area to igneous intrusion and metamorphic rock in the mountains. Seismic strong ground motion was predicted based on the statistical Green’s function method. Considering the damage produced by the 2005 Palu earthquake (Mw 6.3), we also estimated peak ground acceleration distribution at Palu City, with values ranging from 100 gal up to 500 gal on the PGA (peak ground acceleration) scale. Peak ground velocity becomes more than 0.3 m/s in some areas, which may likely lead to severe damage to buildings.

Seismic ground motion, Palu-Koro fault, microtremors, PGA.