Arctic & Antarctica
Nabil Sultan et al., 2020

ARC - The Influence of Tidal Forces Extends to the Arctic's Deep Sea

The Moon’s gravitational pull creates the tides, but its influence extends hundreds of meters below the sea surface too, influencing sensitive methane seeps in the seabed.

From more than 384,000 kilometers away, the Moon’s gravity pulls at Earth and its oceans, even affecting activity hundreds of meters below the sea surface. Oceanographers know that tides can affect methane emissions that seep from the seafloor, and now a research team has shown this influence extends into the deep Arctic.

Unexpected Findings

The team, led by Nabil Sultan, a geotechnics researcher at the French marine sciences institute Ifremer, set out to the Arctic sea. They intended to measure the pressure and temperature of fluids within the sediments along the Vestnesa Ridge on the Svalbard continental margin to see how geological processes in the area might affect that pressure. The team chose two sites that they expected wouldn’t have methane gas plumes, trying to avoid geologically active structures to learn about background sediment properties.

To get their measurements, the team deployed a piezometer, a rodlike device that can measure pressure within sediment pores, equipped with temperature sensors. Embedded 7 meters into the sediment of the Arctic seabed, the device collected data for 4 days before the researchers brought it back to the surface. They collected pore pressure and temperature measurements at two sites, one at 910 meters deep and another at 1,330 meters.

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Read also Impact of tides and sea-level on deep-sea Arctic methane emissions, Nabil Sultan et al., Oct. 9, 2020.