Abstract
Abstract. 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.
Highlights
The Antarctic ice sheet is the largest on the Earth, covering over 98 % of Antarctic continent
Because of the various factors contributing to uncertainty in the Bedmap2 database such as data coverage, basal roughness, and ice thickness measurement and gridding error, the Bedmap2 ice thickness is not exactly accurate with uncertainty varying from site to site
As the accuracy of the H / V method is at the same scale as the uncertainty of the Bedmap2 ice thickness at the 57 stations, the Bedmap2 ice thicknesses are adequate to verify the results derived from the H / V method
Summary
The Antarctic ice sheet is the largest on the Earth, covering over 98 % of Antarctic continent. As a fundamental parameter of the Antarctic ice sheet, ice sheet thickness is significant for dynamic ice sheet modeling of mass balance and sea level changes (Budd et al, 1991; Gogineni et al, 2001; Bamber et al, 2001; Hanna et al, 2013). Seismic waves become more complex when traveling through an ice sheet with thicknesses ranging from hundreds to thousands of meters. Accurate ice sheet thickness is a critical metric for recognizing and denoising seismic multiples trapped inside the ice sheet when imaging crustal and mantle structures below the ice sheet (Lawrence et al, 2006; Hansen et al, 2009, 2010). Given the importance of Antarctic ice sheet structures, many geophysical methods, such as drilling, gravity modeling, radio echo sounding (RES) and active seismic ap- A better understanding of ice sheet thickness and structures can improve the study of the geological structure underneath the ice sheet in Antarctica.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
