1. Determination of anisotropic ice fabric using seismic data Anja Diez, Olaf Eisen, Coen Hofstede, Ilka Weikusat, Ulrich Polom, Thomas Bohlen, Astrid Lambrecht, Christoph Mayer, Heinrich Miller

2. COF & elasticity tensor - Kohnen - Colle Gnifetti  Crystal orientation fabric (COF) & elasticity tensor example: vertical single maximum fabric connection: eigenvalues – elasticity tensor  Kohnen station vertical seismic profiling comparison COF – seismic – radar  Colle Gnifetti velocity analysis derivation of anisotropy 2 Overview

3. COF & elasticity tensor - Kohnen - Colle Gnifetti3 Seismic anisotropy  Ice core: COF eigenvalues: ʎ 1 < ʎ 2 < ʎ 3  Radar: linear relation to dielectric constant ɛ ‘  Seismic: dependence on elasticity tensor C ij c-axis

4.  Example: vertical single max  NMO-velocities (interval) Thomsen parameter δ, γ COF & elasticity tensor - Kohnen - Colle Gnifetti4 Depth conversion stacking velocity ≠ depth conversion velocity 20% 7%

5. COF & elasticity tensor - Kohnen - Colle Gnifetti5 Connection Measured C ij Measured eigenvalues Integration uniform distribution (Nanthikesan, 1994) C ij for different fabrics

6. COF & elasticity tensor - Kohnen - Colle Gnifetti6 COF → Elasticity tensor Data: Kohnen

7. COF & elasticity tensor - Kohnen - Colle Gnifetti  Kohnen Station Dronning Maud Land ~ 750 km southeast of Neumayer III EDML (length 2774 m)  Seismic profile, wideangle, vertical seismic profiling explosives, vibroseis  Radar 60, 600 ns pulse 7 Kohnen station

8. COF & elasticity tensor - Kohnen - Colle Gnifetti Detonation cord: depth 2580 - 100 m 40m intervals 8 VSP dataset

9. COF & elasticity tensor - Kohnen - Colle Gnifetti9 VSP-velocities

10.  Best agreement Gammon (1983) Jona (1952) Bennett (1968)  Gusmeroli (2012, JGR) Borehole sonic logging 23 kHz Best agreement: Dantl (1968) Dependency of seismic waves on frequency Comparison elasticity tensors COF & elasticity tensor - Kohnen - Colle Gnifetti10

11. COF & elasticity tensor - Kohnen - Colle Gnifetti Englacial reflections?Stacked trace 11 Stacked traces

12. COF & elasticity tensor - Kohnen - Colle Gnifetti12 Core – Seismic – Radar

13. COF & elasticity tensor - Kohnen - Colle Gnifetti  Colle Gnifetti Switzerland 4500 m a.s.l. KCI ice core (length 62 m)  Seismic data profile ElViS: P- and SH-wave  Radar data 13 Colle Gnifetti

14. COF & elasticity tensor - Kohnen - Colle Gnifetti14 ElViS reflections stacking = depth conversion velocity COF measurements

15. COF & elasticity tensor - Kohnen - Colle Gnifetti15 Depth shift  Seismics:V ElViS  KCI: V RMS,P0 V NMO density temperature COF  Bed reflection P-wave depth difference → 4 m 7%1%

16. COF & elasticity tensor - Kohnen - Colle Gnifetti16 Connecting seismics & radar Seismic V NMO Radar → depth V RMS,P0 derive interval δ

17. COF & elasticity tensor - Kohnen - Colle Gnifetti17 Deriving anisotropy

18. COF & elasticity tensor - Kohnen - Colle Gnifetti18 Conclusion ConnectionEvaluationComparisonDerivation Integration Seismics & Radar

19. COF & elasticity tensor - Kohnen - Colle Gnifetti19 Thank You! Thanks to: Pascal Bohleber, Reinhard Drews, Günther Druivenga, Jens Eichler, Sepp Kipfstuhl, Daniel Steinhage and the Kohnen logistic team

20. COF & elasticity tensor - Kohnen - Colle Gnifetti20

21. COF & elasticity tensor - Kohnen - Colle Gnifetti21 VSP-velocities Temperature correction gradient 2.3 m/s/K

22. COF & elasticity tensor - Kohnen - Colle Gnifetti Radar 22

23. COF & elasticity tensor - Kohnen - Colle Gnifetti23 COF – Seismic – Radar

24. COF & elasticity tensor - Kohnen - Colle Gnifetti24 Vibro

25. COF & elasticity tensor - Kohnen - Colle Gnifetti25 Picked velocities V NMO

26. COF & elasticity tensor - Kohnen - Colle Gnifetti26 Calculated velocities V RMS,P0

27. COF & elasticity tensor - Kohnen - Colle Gnifetti27 Girdle orientation