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In situ time-series measurements of subseafloor sediment properties

IEEE Journal of Oceanic Engineering

By:
, ,
DOI: 10.1109/JOE.2007.907927

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Abstract

The capabilities and diversity of subsurface sediment sensors lags significantly from what is available for the water column, thereby limiting progress in understanding time-dependent seabed exchange and high-frequency acoustics. To help redress this imbalance, a new instrument, the autonomous sediment profiler (ASP), is described herein. ASP consists of a four-electrode, Wenner-type resistivity probe and a thermistor that log data at 0.1-cm vertical intervals over a 58-cm vertical profile. To avoid resampling the same spot on the seafloor, the probes are moved horizontally within a 20 times 100-cm-2 area in one of three preselected patterns. Memory and power capacities permit sampling at hourly intervals for up to 3-mo duration. The system was tested in a laboratory tank and shown to be able to resolve high-frequency sediment consolidation, as well as changes in sediment roughness. In a field test off the southern coast of France, the system collected resistivity and temperature data at hourly intervals for 16 d. Coupled with environmental data collected on waves, currents, and suspended sediment, the ASP is shown to be useful for understanding temporal evolution of subsurface sediment porosity, although no large depositional or erosional events occurred during the deployment. Following a rapid decrease in bottom-water temperature, the evolution of the subsurface temperature field was consistent with the 1-D thermal diffusion equation coupled with advection in the upper 3-4 cm. Collectively, the laboratory and field tests yielded promising results on time-dependent seabed change.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
In situ time-series measurements of subseafloor sediment properties
Series title:
IEEE Journal of Oceanic Engineering
DOI:
10.1109/JOE.2007.907927
Volume
32
Issue:
4
Year Published:
2007
Language:
English
Publisher:
IEEE
Contributing office(s):
Coastal and Marine Geology Program
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
IEEE Journal of Oceanic Engineering
First page:
862
Last page:
871
Number of Pages:
10