Characterization of dynamic site properties in Quaternary-Tertiary geological formations using passive seismic techniques

Abstract

This study presents a preliminary quantification of subsurface dynamic properties within the Quaternary-Tertiary geological formations in Jantho, Aceh Besar, Indonesia. The area lies near three major seismic sources, the subduction zone of the Indo-Australian plate under the Eurasian plate, the Great Sumatran Fault, and the Mentawai Fault, so Jantho is exposed to significant seismic ground shaking, requiring attention in the city's disaster risk reduction strategy. A non-invasive passive seismic approach is used. Data from four locations within these formations are analyzed to determine four primary seismic properties: fundamental site frequency (f0), seismic amplification factor (A0), subsurface shear-wave velocity (Vs) profiles, and seismic site classification. The estimated sitedominant frequency ranges from 4.8 to 7.0 Hz, amplification (A0) from 1.5 to 3.0, and near-surface Vs generally from 150 to 300 m/s. Calculated Vs30 values range from 135 to 346 m/s, categorized as seismic site class D/E. These findings provide a critical technical foundation for seismic hazard mitigation in Jantho.