DETERMINED SOIL CHARACTERISTIC OF PALU IN INDONESIA BY USING MICROTREMOR OBSERVATION

Abstract

The Palu city, which is located in the active seismic zone of the Palu-Koro fault. Several powerful
earthquakes have struck Palu city at previous years. One of the greatest earthquake event occurred in year 2006
which 6.2 Mw, about more a hundred buildings and houses were collapsed due to this earthquake. Palu-Koro
fault also produced several tsunami events in year of 1927, 1968 and 1996. The latest earthquake struck Palu
on 2012 (7.2 Mw) and it produced local tsunami. Since no soil profile map of Palu region available, we
performed single observations of microtremors at 122 sites in Palu. Its results enabled us to estimate the sitedependent amplification characteristics of earthquake ground-motion. We also conducted a 8-site microtremor
array investigation to gain a representative determination of the soil condition of subsurface structures in Palu.
From the dispersion curve of array observations, the central business district of Palu corresponds to relatively
from soft soil to medium condition. Predominant periods due to horizontal vertical ratios (HVSRs) in Palu are
in the range of 1.2 to 2.5 s.