Crustal structure of the Northern Victoria Land, Antarctica, from ambient seismic noise tomography

Abstract

The Northern Victoria Land is, an area of tectonically interest in Antarctica, comprised of the West Antarctic Rift System (WARS), the precambrian East Antarctic Craton and the Transantarctic Mountains (TAMs) which separates two different tectonic regions. We performed ambient noise tomography to investigate the crustal structure of this area using data from the new Transantarctic Mountains Northern Network (TAMNET) and the Korean Polar Seismic Network (KPSN), which is operated by the Incorporated Research Institutions for Seismology-Program for the Array Seismic Studies of the Continental Lithosphere (IRIS-PASSCAL) and the Korea Polar Research Institute (KOPRI), respectively. By cross-correlating 1-year ambient noise data recorded at 28 stations, we derived fundamental mode Rayleigh wave Green's functions for all possible station pairs. Rayleigh wave group velocities at periods from 2 to 30 s were determined by using the multiple-filter analysis technique. Only 100 to 300 measurements at period range between 3 to 22 s, which pass the selection criteria based on the signal-to-noise ratio and seasonal variability, were used for the travel time tomography. The group velocity maps are generally well correlated with both the surface geology and the topographic feature of the study region. The velocity maps are inverted for shear velocities applying a 1-D linearized least-square inversion technique. Relatively high velocities are observed at shallow depth in TAMs and low velocities are found in East Antarctic Craton and Ross Sea region, which seems to be related to the presence of sediment. In Ross Sea region, the velocities increase sharply to mantle value between 14 to 20 km depth, implying thin crust beneath the coastal area.