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A buried Antarctic lake drained through hydrofracture

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Ground-penetrating radar caught a buried meltwater lake draining through vertical fractures at an East Antarctic ice-shelf grounding zone.

Source

Observations of Buried Lake Drainage on the Antarctic Ice Sheet

Dunmire D, Lenaerts JTM, Banwell AF, et al. · Geophysical research letters · 2020

doi.org/10.1029/2020gl087970Read the full paper ↗4 citationscc by

Study at a glance

Design
Other — GPR before/after collapse plus SNOWPACK and Sentinel-1 monitoring of a buried meltwater lake
N
N=1 · Single buried lake (~1.5 billion m³) at an East Antarctic ice-shelf grounding zone
Population
Buried meltwater lake on the grounding zone of an East Antarctic ice shelf
Outcome
Drainage through vertical fractures and implications for ice-shelf weakening

Structured fields used in claim comparison tables when every cited study has a complete layer.

What they did

The team surveyed a buried lake on the grounding zone of an East Antarctic ice shelf with ground-penetrating radar before and after collapse, combined that with SNOWPACK energy-balance modeling forced by a nearby weather station, and tracked surface-height and Sentinel-1 backscatter changes.

What they found

The lake sat about 3.5 m below the surface with ~1.5 billion m³ of water and drained through preexisting lake-bed fractures. DEM differencing showed a multi-metre surface drop, and Sentinel-1 backscatter jumped during March–April 2016. Fractures can advect onto the floating shelf and threaten buttressing.

The limits

What it doesn't show

This is one lake at one grounding-zone site, not a continent-wide census. Volume is likely underestimated because the GPR grid missed the southern shoreline, and the study cannot prove that these fractures currently reach the ice-shelf front or trigger collapse.

Key terms

Hydrofracture
Crack opening and downward water drainage when meltwater pressurizes a fracture in ice.
Buried lake
Meltwater ponded on ice then insulated under later snowfall so liquid water persists beneath the surface.
Grounding zone
Transition where grounded ice sheet becomes a floating ice shelf.
Ice-shelf buttressing
Resistive force of a floating shelf that slows inland ice flow into the ocean.
GPR
Ground-penetrating radar used to image buried ice, water, and fractures.

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The buried lake drained mainly by:

Common questions

How did the buried lake form?

Katabatic winds expose low-albedo blue ice, meltwater ponds in depressions, then snowfall buries and insulates the water.

How do we know it drained through fractures?

Precollapse GPR showed lake-bed discontinuities; postcollapse profiles showed large vertical discontinuities aligned with advection of those fractures.

Why does this matter for sea level?

If fractures advect onto ice shelves, they can weaken the buttress that holds back inland ice.

When did drainage likely start?

Sentinel-1 backscatter rose most between 25 March and 30 April 2016, matching the fractured southern lake bed.

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