TY - JOUR
T1 - Distribution of preferred ice crystal orientation determined from seismic anisotropy
T2 - Evidence from Jakobshavn Isbræ and the North Greenland Eemian Ice Drilling facility, Greenland
AU - Vélez, José A.
AU - Tsoflias, Georgios P.
AU - Black, Ross A.
AU - Van der Veen, Cornelis J.
AU - Anandakrishnan, Sridhar
N1 - Funding Information:
This work was made possible by the National Science Foundation and CReSIS (grant no. ANT-0424589) at the University of Kansas in collaboration with Penn State Ice and Climate Exploration (L. Peters, K. Riverman, A. Muto, K. Christianson, and D. Voigt). We would like to express appreciation to J. P. Steffensen, D. Dahl-Jensen, and all the staff members at NEEM for their support in this investigation. Partial student funding for this investigation was provided by NASA’s Harriet Jenkins Pre-Doctoral Fellowship program. Finally, we would like to make a special mention of appreciation to A. Hoch for his support in this investigation.
Publisher Copyright:
© 2016 Society of Exploration Geophysicists.
PY - 2015/3/6
Y1 - 2015/3/6
N2 - Preferred crystal orientation fabrics (COFs) within an ice sheet or glacier are typically found from ice cores. We conducted experiments at the North Greenland Eemian Ice Drilling (NEEM) facility ice core location, where COF data were available at Jakobshavn Isbræ west Greenland, to test if COF can be determined seismically. We used observations of anisotropic seismic wave propagation on multioffset gathers and englacial imaging from a 2D reflection profile. Anisotropy analysis of the NEEM data yielded mean c-axes distributed over a conical region of 30° to 32° from vertical. No internal ice seismic reflectors were imaged. Direct COF measurements collected in the ice core agreed with the seismic observations. At Jakobshavn Isbræ, we used a multioffset gather and a 2D reflection profile, but we lacked ice core data. Englacial reflectors allowed the determination of ice column interval properties. Anisotropy analysis found that the upper 1640 m of the ice column consisted of cold (~-10°C) and mostly isotropic ice with c-axes distributed over a conical region of 80° from vertical. The lower 300 m of the ice column was characterized by warm (> -10°C) ice with COF.These observations were consistent with complex ice fabric development and temperature estimations over the same region of Jakobshavn Isbræ. This study demonstrated that the ice sheet and glacier ice anisotropy information can be gained from seismic field observations.
AB - Preferred crystal orientation fabrics (COFs) within an ice sheet or glacier are typically found from ice cores. We conducted experiments at the North Greenland Eemian Ice Drilling (NEEM) facility ice core location, where COF data were available at Jakobshavn Isbræ west Greenland, to test if COF can be determined seismically. We used observations of anisotropic seismic wave propagation on multioffset gathers and englacial imaging from a 2D reflection profile. Anisotropy analysis of the NEEM data yielded mean c-axes distributed over a conical region of 30° to 32° from vertical. No internal ice seismic reflectors were imaged. Direct COF measurements collected in the ice core agreed with the seismic observations. At Jakobshavn Isbræ, we used a multioffset gather and a 2D reflection profile, but we lacked ice core data. Englacial reflectors allowed the determination of ice column interval properties. Anisotropy analysis found that the upper 1640 m of the ice column consisted of cold (~-10°C) and mostly isotropic ice with c-axes distributed over a conical region of 80° from vertical. The lower 300 m of the ice column was characterized by warm (> -10°C) ice with COF.These observations were consistent with complex ice fabric development and temperature estimations over the same region of Jakobshavn Isbræ. This study demonstrated that the ice sheet and glacier ice anisotropy information can be gained from seismic field observations.
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U2 - 10.1190/GEO2015-0154.1
DO - 10.1190/GEO2015-0154.1
M3 - Article
AN - SCOPUS:84953378200
VL - 81
SP - WA111-WA118
JO - Geophysics
JF - Geophysics
SN - 0016-8033
IS - 1
ER -