Erosion and potential geological hazards chain in the East African Rift System controlled by volcanic sediments properties and geological structure

Abstract

The East African Rift System (EARS) hosts extensive unconsolidated volcanic sediments whose unique physicochemical characteristics interact with geological structure to drive erosion and geological hazard cascades. Focusing on the Central Kenyan Rift (CKR), this study integrates geotechnical testing, sediment property analysis, and geophysical imaging to decipher the mechanisms controlling erosion evolution and associated geological hazard chains. Key findings reveal: (1) Four characteristic erosional landforms (sinkholes, pipes, gullies, badlands) developed in CKR volcanic sediments; (2) Volcanic sediments exhibited high vulnerability indices with >40 % macroporosity (>32 μm), bimodal grain size distributions, and alkaline profiles with surface Na+/metal enrichment. (3) Electrical resistivity tomography (ERT) delineated the erosion-piping networks, while Shallow seismic exploration (SSE) identified the strata dislocation patterns comprising stratal fracturing, normal faulting, reverse faulting, and uplifts. (4) Synergistic coupling between sediment properties and geological structure governs erosion and potential geological hazards. This integrated study advances understanding of erosion mechanisms of volcanic sediments in rift-related geological hazard cascades, providing critical insights for infrastructure resilience and land-use planning in active tectonic settings.