How complete is the record of major earthquakes from submarine and sublacustrine mass flow deposits, and which settings provide the most complete earthquake record?
Maarten Heijnen | NOC Southampton
Submarine landslides can initiate several different types of downslope run-out mass flows. One of the most important type is turbidity currents. These turbulent flows of suspended sediment have shown to pose a hazard to seafloor infrastructure (such as offshore oil and gas, and telecommunication links) and can reveal information about the initiating landslides and its triggering mechanism. The deposits of these flows have been proposed to be a valuable record of these initial triggers, especially earthquakes, since some of the largest mass flows have been triggered by earthquakes.
A better understanding of how and where these deposits are formed, what locations are the most reliable and complete recorders of events, and how a trigger can be distinguished from a deposit is critical to be able to correctly interpret records of submarine mass flows. There have always been remarkably few direct measurements of these turbidity current events, however, new efforts have resulted in some high quality timelapse bathymetry data and direct flow measurements. I will analyse several of these scarce and novel datasets and I will be involved in new expeditions to monitor active turbidity current systems. This project will provide one of the first opportunities to understand how these flows behave, modify the seafloor, and thus, how we can interpret their resultant deposits. This project aims to address three main research aims:
- Understand how submarine channel morphology evolves in response to recurrent turbidity currents that are triggered by submarine landslides. What locations in a turbidity current system can potentially form long-term records of past events?
- How strongly is flow mode controlled by initial trigger? Can we reliably diagnose an earthquake trigger from other triggers?
- To what extent do environmental controls (other than the original trigger) affect flow behaviour and how do flows evolve from proximal to distal?