My research aims to understand the fundamental processes that underpin a range of sediment laden flows, how we can model such flows experimentally and numerically, and determine how flow dynamics are ultimately recorded in their deposits in the geological record. Brief information about my various research projects can be found below and more information is available in the relevant publications, or by contacting me directly.
Direct monitoring of submarine gravity currents
I have several projects that use state-of-the-art techniques to directly measure the dynamics of field-scale submarine gravity currents. Despite their scale and importance in transporting sediment around our planet, there are currently remarkably few direct measurements of these types of flows.
I have been studying the three-dimensional flow dynamics of a field-scale submarine gravity current on the Black Sea shelf. This flow provides an opportunity to measure gravity current dynamics in exceptional detail and provides a rare analogue to dilute sediment-laden turbidity currents. This study is funded by NERC and is in collaboration with colleagues at the Universities of Southampton, Leeds, Hull and the National Oceanography Centre.
In 2014 I will be involved in deploying an array of monitoring equipment in Monterey Canyon, California. This project aims to make the first synchronous quantification of flow and suspended sediment dynamics in a field-scale submarine gravity current. This study is a collaborative study funded by NERC, MBARI and the USGS.
Understanding flow dynamics from modern and ancient deposits
The paucity of direct measurements of submarine gravity currents means that much of our understanding of the dynamics of these flows results from studying their deposits either in ancient outcrops or the deposits that they have left behind on the modern seafloor.
The Miocene Marnoso Arenacea Formation, Italy and the modern Agadir Basin, offshore Morocco are two unusual systems in which the deposits of individual flows can be correlated in detail over distances in excess of 100 and 1000 km respectively. Analysis of these deposits provides insight into the dynamics of the flows that created them. This study was funded by NERC and UKTAPS.
Submarine canyons are the conduits by which sediment, pollutants and nutrients are transported from the continental shelf out into the deep sea. I am currently analysing a dataset of several hundred precisely located cores collected using remotely operated vehicles in submarine canyons along the Californian margin in order to understand how sediment is transported and stored within these systems. This study is funded by MBARI.
Experimental and numerical modelling
The biggest direct dataset that we have about the dynamics of submarine flows are the deposits that they leave behind in the geological record. However, these deposits pose as many questions about flow dynamics as they answer. Experimental and numerical models provide opportunities to test new hypotheses about flow dynamics.
It is often difficult to generate high-concentration, fast flows in the laboratory. The annular flume in the sediment dynamics laboratory at the University of Southampton has no such issues. Experiments using high concentration muddy suspensions in this flume tank have revealed the profound influence of small changes in the mud content of flows on flow rheology and deposit morphology. Collaboration with numerical modellers at the University of Bristol has enabled the results of these experimental studies to inform and validate realistic numerical models of multiphase flows. These studies were funded by NERC and UKTAPS.
Turbidites are increasingly being used as a proxy for past earthquakes because they may provide information about earthquake magnitude and recurrence intervals over multiple earthquake cycles. The results of such studies inform hazard prediction and mitigation strategies. We found no evidence that recent large magnitude earthquakes on the Sumatran margin generated widespread turbidites on the seafloor. This questions the validity of applying turbidite palaeoseismology on the Sumatran margin and highlights the need for more studies to test the technique globally.
Geology and Geophysics
Dr Esther Sumner
Monterey Bay Aquarium Research Institute, 7700, Sandholdt Road, Moss Landing, CA 95039