Swept away by a turbidity current in Mendocino submarine canyon, California

Abstract

AbstractWe present unique observations and measurements of a dilute turbidity current made with a remotely operated vehicle in 400 m water depth near the head of Mendocino Canyon, California. The flow had a two‐layer structure with a thin (0.5 to 30 m), relatively dense (<0.04 vol %) and fast (up to ~1.7 m/s) wedge‐shaped lower layer overlain by a thicker (up to 89 m) more dilute and slower current. The fast moving lower layer lagged the slow moving, dilute flow front by 14 min, which we infer resulted from the interaction of two initial pulses. The two layers were strongly coupled, and the sharp interface between the layers was characterized by a wave‐like instability. This is the first field‐scale data from a turbidity current to show (i) the complex dynamics of the head of a turbidity current and (ii) the presence of multiple layers within the same event.