Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise
We report on a successful application of the horizontal-to-vertical spectral ratio (H / V) method, generally used to investigate the subsurface velocity structures of the shallow crust, to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2018-03-01
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Series: | The Cryosphere |
Online Access: | https://www.the-cryosphere.net/12/795/2018/tc-12-795-2018.pdf |
Summary: | We report on a successful application of the horizontal-to-vertical spectral
ratio (H / V) method, generally used to investigate the subsurface
velocity structures of the shallow crust, to estimate the Antarctic ice sheet
thickness for the first time. Using three-component, five-day long, seismic
ambient noise records gathered from more than 60 temporary seismic stations
located on the Antarctic ice sheet, the ice thickness measured at each
station has comparable accuracy to the Bedmap2 database. Preliminary analysis
revealed that 60 out of 65 seismic stations on the ice sheet obtained clear
peak frequencies (f0) related to the ice sheet thickness in the H / V
spectrum. Thus, assuming that the isotropic ice layer lies atop a high
velocity half-space bedrock, the ice sheet thickness can be calculated by a
simple approximation formula. About half of the calculated ice sheet
thicknesses were consistent with the Bedmap2 ice thickness values. To further
improve the reliability of ice thickness measurements, two-type models were
built to fit the observed H / V spectrum through non-linear inversion.
The two-type models represent the isotropic structures of single- and
two-layer ice sheets, and the latter depicts the non-uniform, layered
characteristics of the ice sheet widely distributed in Antarctica. The
inversion results suggest that the ice thicknesses derived from the two-layer
ice models were in good concurrence with the Bedmap2 ice thickness database,
and that ice thickness differences between the two were within 300 m at
almost all stations. Our results support previous finding that the Antarctic ice
sheet is stratified. Extensive data processing indicates that the time length
of seismic ambient noise records can be shortened to two hours for reliable
ice sheet thickness estimation using the H / V method. This study extends
the application fields of the H / V method and provides an effective and
independent way to measure ice sheet thickness in Antarctica. |
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ISSN: | 1994-0416 1994-0424 |