On-ice Vibroseis: What lies beneath Ekström Ice Shelf, East Antarctica?

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On-ice Vibroseis: What lies beneath Ekström Ice Shelf, East Antarctica?

Emma C. SMITH ¹

Reinhard DREWS

²

, Todd EHLERS

²

, Dieter FRANKE

³

, Christoph GAEDICKE

³

, Coen HOFSTEDE

¹

, Gerhard KUHN

¹

, Astrid LAMBRECHT

⁴

, Christoph MAYER

⁴

, Ralf TIEDEMANN

^1,5

, and Olaf EISEN

^1,5

1

Alfred-Wegener-Institut (AWI), Germany,

²

Department of Geosciences, University of Tübingen, Germany

3

BGR, Germany,

⁴

Geodesy and Glaciology, Bavarian Academy of Sciences and Humanities, Germany,

5

Department of Geosciences, University of Bremen, Germany

O VER VI EW

1. Motivation 2. Method:

Vibroseis on Ice

3. Location and

Data

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T W O MI N U T E MAD N ESS _What?

•  ~700 km of seismic vibroseis surveys

Why?

•  Evidence of paleo-ice flow and retreat

•  Geological history of region

•  Ice-ocean interaction

•  Predictions of SLR contribution

Sub-EIS-Obs: Vibroseis on ice

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T W O MI N U T E MAD N ESS

Sub-EIS-Obs: Vibroseis on ice

a

What? a’

•  ~700 km of seismic vibroseis surveys

Why?

•  Evidence of paleo-ice flow and retreat

•  Geological history of region

•  Ice-ocean interaction

•  Predictions of SLR contribution

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T W O MI N U T E MAD N ESS Key Findings:

•  Sea-floor trough

•  Glacial debris deposits 10-60 m thick

•  Volcanic Explora wedge outcrop imaged

•  Other features of ice flow and retreat

Sub-EIS-Obs: Vibroseis on ice

a

a’

Two-way travel time (ms) ₄₀₀

600

800

1000

~50 m 2500 m

Seismic multiple

a a’

Glacial debris Truncated dipping sediment

Volcanic Explora wedge

Base glacial debris Sea floor Explora wedge

3. Location

and Data

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Motivation

T W O MI N U T E MAD N ESS MO T IV A T IO N

The sea-floor and sub-sea floor topography beneath Antarctic ice shelves holds a wealth of information:

•  Sea floor topography -> past ice dynamics

•  Sub-sea floor -> geological history

•  The shape of the cavity -> implications of ocean circulation and ice melt

So how do we „see“ beneath the ice shelf?

Seismic reflection vibroseis data collected between (2010 -2018) on Ekström ice shelf used to map the sea-floor bathymetry and sub-sea floor structures.

? ?

?

Credit: Borrowed with permission from Reinhard Drews

? ?

?

Credit: Borrowed with permission from

Reinhard Drews

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MET H O D : VI BR O SEI S

Eisen et al., Polar Sci., 2015

1500 m, 60 channels

Sweep: 10 – 220 Hz Time: 10 seconds SPs 75 – 750 m

Vibroseis on ice!

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LO C A T IO N & D A TA

Ekström Ice Shelf

Antarctic Peninsula

Ronne- Filchner Ice Shelf

Ekström Ice Shelf

Please click to view seismic

data

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LO C A T IO N & D A TA

Two-way travel time (ms) 400 600

800

Seismic multiple

x x’

~50 m

2500 m

Volcanic Explora wedge Sediment wedge

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold) ^x

x’

800

Seismic multiple

x x’

~50 m

2500 m

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LO C A T IO N & D A TA

800

Seismic multiple

x x’

~50 m

2500 m

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold) ^x

x’

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LO C A T IO N & D A TA

600

800

1000

~50 m 2500 m

Seismic multiple

x’

x

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold)

x

x’

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LO C A T IO N & D A TA

600

800

1000

~50 m 2500 m

Seismic multiple

x’

x

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold)

x

x’

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LO C A T IO N & D A TA Back to Map >

Two-way travel time (ms)

400

600

800

1000

~50 m 2000 m

Seismic multiple

x’

x

Interpretation ON Interpretation OFF

2018 ‒ SP 125 m (6 fold)

x

x’

400

600

800

1000

~50 m 2000 m

Seismic multiple

x’

x

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LO C A T IO N & D A TA Back to Map >

400

600

800

1000

~50 m 2000 m

Seismic multiple

x’

x

Interpretation ON Interpretation OFF

2018 ‒ SP 125 m (6 fold)

x

x’

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LO C A T IO N & D A TA Back to Map >

600

800

1000

~50 m

3000 m

Seismic multiple Sediment wedge

x x’

Interpretation ON Interpretation OFF

400

2018 ‒ SP 75 m (10 fold) ^x

x’

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LO C A T IO N & D A TA Back to Map >

600

800

1000

3000 m

Seismic multiple

x x’

Interpretation ON Interpretation OFF

~50 m 400

2018 ‒ SP 75 m (10 fold)

Sediment wedge

x’

x

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LO C A T IO N & D A TA Back to Map >

600

800

1000

Seismic multiple

x x’

Interpretation ON Interpretation OFF

3500 m

~50 m 400

1200

1400

1600

2014 ‒ SP 750 m (1 fold)

x

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LO C A T IO N & D A TA Back to Map >

600

800

1000

Seismic multiple

x x’

3500 m

~50 m 400

1200

1400

1600

Interpretation ON Interpretation OFF

2014 ‒ SP 750 m (1 fold)

x

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LO C A T IO N & D A TA

400

600

800

1000

~50 m

2000 m

Seismic multiple

Truncated dipping sediment

x’

x

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold)

Sediment wedge

x

x’

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LO C A T IO N & D A TA

400

600

800

1000

~50 m

2000 m

Seismic multiple

x’

x

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold)

Sediment wedge

x’

x

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LO C A T IO N & D A TA

200

400

600

800

Seismic multiple

Back to Map >

Interpretation ON Interpretation OFF

~50 m 1500 m

2017 ‒ SP 125 m (6 fold)

Sediment wedge

x x’

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LO C A T IO N & D A TA

200

400

600

800

~50 m 1500 m

Seismic multiple

x x’

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold)

Sediment wedge

x

x’

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LO C A T IO N & D A TA

800

Seismic multiple

x x’

~50 m

1500 m

Back to Map >

2017 ‒ SP 50 m (15 fold)

Interpretation ON Interpretation OFF

x

x’

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LO C A T IO N & D A TA

800

Seismic multiple

x x’

~50 m

1500 m

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 50 m (15 fold) ^x

x’

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LO C A T IO N & D A TA

200

400

600

Seismic multiple

x x’

Glacial debris

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 50 m (15 fold)

Seismic multiple

~50 m 2000 m

x

x’

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LO C A T IO N & D A TA

400

600

800

1000

~50 m

1500 m

Seismic multiple

x’

x

Back to Map >

Interpretation ON Interpretation OFF

2017 ‒ SP 125 m (6 fold)

Possible GZW

x x’

Possible GZW

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LO C A T IO N & D A TA

400

600

800

1000

~50 m

1500 m

Seismic multiple

x’

x

Back to Map >

2017 ‒ SP 125 m (6 fold)

Possible GZW

x

Interpretation ON x’

Interpretation OFF

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Antarctic Peninsul

a

Ronne- Filchner Ice Shelf

Ekström Ice Shelf

On-ice Vibroseis: What lies beneath Ekström Ice Shelf, East Antarctica?