Imaging the Ice Sheet and Uppermost Crustal Structures with a Dense Linear Seismic Array in the Larsemann Hills, Prydz Bay, East Antarctica

Abstract

Comprehensive geophysical surveys including magnetotelluric, seismic, and aerial gravity–magnetic surveys are essential for understanding the history of Antarctic tectonics. The ice sheet and uppermost structure derived from those geophysical methods are relatively low resolution. Although ice-penetrating radar can provide high-resolution reflectivity images of the ice sheet, it cannot provide constraints on subice physical properties, which are important for geological understanding of the Antarctic continent. To obtain high-resolution images of the ice sheet and uppermost crustal structure beneath the Larsemann Hills, Prydz Bay, East Antarctica, we conduct an ambient noise seismic experiment with 100 short-period seismometers spaced at 0.2 km intervals. Continuous seismic waveforms are recorded for one month at a 2 ms sampling rate. Empirical Green’s functions are extracted by cross correlating the seismic waveform of one station with that of another station, and dispersion curves are extracted using a new phase-shift method. A high-resolution shear-velocity model is derived by inverting the dispersion curves. Furthermore, body waves are enhanced using a set of processing techniques commonly used in seismic exploration. The stacked body-wave image clearly shows a geological structure similar to that revealed by the shear-wave velocity model. This study, which is the first of its kind in Antarctica, possibly reveals a near-vertical intrusive rock covered by an ice sheet with a horizontal extent of 4 km. Our results help to improve the understanding of the subice environment and geological evolution in the Larsemann Hills, Prydz Bay, East Antarctica.

Environment‐Modulated Glacial Seismicity Near Dålk Glacier in East Antarctica Revealed by Deep Clustering

“…They are concentrated near the grounding line (Figure 13b). The optimal velocities are ∼1.7 km/s, consistent with the surface wave velocity within the glacier (Fu et al., 2023).…”

Geophysical Evidence of the Collisional Suture Zone in the Prydz Bay, East Antarctica

“…velocities previously published byFu et al (2022), shown in Figures2a-2c, respectively. The stacked CRF results, generated from four earthquakes with magnitudes greater than 5.8 (indicated by purple circles in FigureS1in Supporting Information S1), are presented in Figure2b.…”

“…Seismic analysis of the Larsemann Hills seismic data yielded three seismic products: the average crustal Poisson's ratio (Zhu & Kanamori, 2000) beneath each seismic station, stacked Coherent Receiver Function (CRF) image, and shallow seismic velocities previously published by Fu et al. (2022), shown in Figures 2a–2c, respectively. The stacked CRF results, generated from four earthquakes with magnitudes greater than 5.8 (indicated by purple circles in Figure S1 in Supporting Information ), are presented in Figure 2b.…”

“…While the low Versus zone appears to be distinct from the deeper crustal deformation zone, its formation is closely associated with the fault system. The fault system in the suture zone region could be highly complex, and it may influence (O’Connell & Budiansky, 1974) or guide the formation (Fu et al., 2022) of the low Versus zone in the adjacent upper crust.…”

Shallow Ice‐Sheet Composite Structure Revealed by Seismic Imaging Near the West Antarctic Ice Sheet (WAIS) Divide Camp

“…Indeed, shear waves enable better constraints on seismic anisotropy in ice sheets compared to P waves (Diez et al., 2016). Surface wave dispersion curve inversion has been widely used for imaging the shallow structures of the Antarctic (Diez et al., 2016; Fu et al., 2021; Picotti et al., 2015; Shen et al., 2018). The derived 1D velocity models are first‐order approximations of a heterogeneous Earth.…”