Integration of PSHA and site response analysis for quantifying liquefaction-induced ground settlements using in-situ testing

Abstract

Numerous past moderate-to-strong earthquakes have induced soil liquefaction, leading to severe structural damage in many locations worldwide, including in the Aceh Province of Indonesia. This study aims to assess and map the soil liquefaction potential for the city of Meulaboh, Indonesia, by integrating probabilistic seismic hazard analysis (PSHA) and site response analysis into liquefaction-induced ground settlement using in-situ test data involving the quasi-static cone penetration test (q-CPT). The novelty of this study lies in integrating PSHA with site-response analysis to enhance the liquefaction potential assessment. The adopted method in the present study is outlined as follows. Firstly, PSHA was carried out to quantify the bedrock seismic ground motion, i.e., bedrock peak ground acceleration, in a location by considering all possible seismic occurrences within a certain period. Secondly, to obtain the most representative soil peak ground acceleration, site response analysis was performed using the bedrock peak ground acceleration of PSHA and sub-surface models developed from various sub-surface site investigation methods, i.e., quasi-static cone penetration test (q-CPT), boreholes, and microtremors measurements, across the study area. Finally, a liquefaction assessment was carried out by means of the ground settlements, liquefaction potential index (LPI), and liquefaction severity number (LSN) by considering various seismic hazard scenarios of 10% and 2% probability of exceedance (PoE). Further liquefaction assessments were also carried out in the case of the historical M 9.1 Sumatra-Andaman earthquake and the M 7.5 earthquake scenarios. These scenarios represent the most common and critical seismic magnitude for evaluating liquefaction hazard potential. The worst-case results of the liquefaction assessment in the present study suggests that the estimated ground settlement due to soil liquefaction within the study area (city of Meulaboh) can be up to ∼309 mm, LPI is classified as very high hazard (LPI > 15), and LSN is categorized as moderate to severe (20 < LSN ≤ 30). Based on the spatial distribution analysis by means of maps for all seismic event scenarios, the main vulnerable part of the city of Meulaboh is on the southern tip and along the coastal areas.