3D geological modelling and geotechnical characteristics of quaternary sediments for seismic site effect analysis: case study of Banda Aceh City, Indonesia

Abstract A soil model that describes the geometry and physical and mechanical properties of superficial geological layers is important in studying site effect conditions due to amplification or long-period ground motion for seismic hazard evaluation. These conditions have been observed in the powerful earthquake that affected this region on December 26, 2004. The Krueng Aceh River delta is a fluvial sedimentary basin with an increasing number of infrastructures, particularly high-rise buildings, large water tanks and long-span bridges. Therefore, the development of 3D models and geotechnical characteristics is essential. A 3D model is developed using a combination of lithologies derived from 17 groundwater wells and 23 geotechnical boreholes. Standard penetration test values are used to generate the geotechnical characteristic model. Results show that the solid model and fence diagram correctly visualise the geometry and geotechnical properties of the sedimentary layers. Geologists and engineers can use this effective method in predicting underground conditions for seismic site effect analysis.