Using a geomicrobial approach to investigate the geological records of coastal hazards

• Main Author: Yap, Wenshu
• Other Authors: Federico Lauro
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Geology
• Online Access: https://hdl.handle.net/10356/156180
• Institution: Nanyang Technological University

Geoscientists use overwash deposits preserved in the geological records to infer the long-term coastal hazard risks that complement the development of a reliable coastal hazard risk assessment. This thesis aims to examine the potential of using environmental DNA to address the primary challenges in historical coastal hazard study – the inability to differentiate overwash deposits from non-overwash sediments. This thesis first demonstrated that the microbial community in the overwash deposits is significantly different from non-overwash soil and sediments. This microbial community-based approach can reliably distinguish between tsunami and storm deposits that occurred at the exact location. In addition, this approach can robustly discriminate tsunami deposited beyond 600 years old from the intercalating non-tsunami sediments. Lastly, this approach is sufficient to determine tsunami deposits despite being formed by a lower energy and transportation capability event, and each site has site-dependent characteristics. The integration of using the molecular technique to examine geological records represents a significant advancement in historical coastal hazard study. This geomicrobial approach will inevitably improve the reconstruction of long-term coastal hazard records essential in assessing coastal communities' risk and vulnerability.