Assessment of Liquefaction Vulnerability in Silt and Sand Predominance Soil Layers of Bori City

Abstract The geotechnical characteristics of the sub-soil layers in Bori, Nigeria were investigated to assess the liquefaction vulnerability of the predominantly silt and sandy soils. Standard penetration tests (SPT) were conducted, revealing significant depth-dependent variations in soil resistance. The upper 0–10 m of soil exhibited very low SPT-N values (3–10 blows), indicating loose, soft and highly compressible deposits. This makes the shallow layers highly susceptible to liquefaction during seismic events, as emphasized by prior studies. Deeper soil layers showed an increasing trend in SPT-N values (15–30 blows at 10–20 m, 30–36 blows beyond 20 m), suggesting denser and more compact conditions with reduced liquefaction potential. The natural moisture content also exhibited depth-dependent behavior, with higher values (20-29.3%) in the upper layers and decreasing values (7.9–15%) at greater depths. This moisture content variation, combined with the SPT-N trends, further highlights the liquefaction vulnerability of the shallow soil profile. Specific gravity analysis showed values typical of the Niger Delta region, ranging from 2.60–2.72, with lower values in the upper layers and gradual increases at depth. The comprehensive geotechnical dataset provided by this study fills an important gap in the knowledge of the Bori sub-soil conditions. The findings can inform the development of site-specific hazard mitigation plans, earthquake-resistant foundation design guidelines, and other geotechnical engineering applications to enhance resilience in the region, which faces risks from tremors and potential seismic events.