Timing the triggers: Radiocarbon chronostratigraphy for geohazard assessment in offshore Myanmar - conference paper

Submarine geohazards such as turbidity currents and slope failures represent significant risks for offshore infrastructure developments in tectonically active regions like the Rakhine Basin, offshore Myanmar. This study integrates radiocarbon chronostratigraphy, sedimentological logging and geophysical analysis from twelve sediment cores (collected between approximately 110 and 980 m water depth) to establish a robust framework for a geohazard assessment. Results show that hemipelagic mud, accummulating uniformly at approximately 20 cm/1000 years, has dominated sedimentation over the past ~6,000 years. However, older sediment sequences (>6,000 years BP) contain thin, silty turbidites interpreted as hyperpycnal flows linked to intensified monsoonal runoff. The cessation of these events coincides with significant post-glacial sea-level rise and regional climate-driven aridification due to a northward shift and weakening of the Indian Summer Monsoon. Mass transport deposits identified within cores are geographically constrained, yet geophysical analyses indicate the widespread occurrence of buried debris-flow features beneath the modern seabed. These buried paleo-hazards highlight historically significant sediment instability events, which remain important considerations for infrastructure siting.