High-Resolution Imaging of the Firn Layer in Antarctic Near the West Antarctic Ice Sheet Divide Camp
Description:
We analyze the 7-day seismic recordings from Antarctic near the West Antarctic Ice Sheet (WAIS) Divide Camp to image velocity structure of the firn layer. The WAIS array includes 76 3-component Z-Land Gen2 Fairfield seismic stations along a ~2.2 km line with station spacing of 30 m. We estimate high-resolution near-surface seismic velocities, especially at the firn layer, using ambient noise data recorded by this array. We first calculate the ambient noise cross-correlation, and use phase-matched filter to isolate different signals in the cross-correlation. Then three-station interferometry is applied to denoise the surface wave signals for accurate Rayleigh wave travel-time measurements in the 3-30 Hz frequency band. We also obtain the H/V ratios of the Rayleigh wave at 5-25 Hz by stacking the waves at a target station from different virtual sources after removing the phase difference between different station pairs, which improves the signal-to-noise ratio of H/V ratio measurement. Joint inversion of Rayleigh wave phase velocity and H/V ratios suggests that S-wave velocity (Vs) increases from ~200 m/s to ~1200 m/s in the top ~20 m with a sharp velocity interface at ~5-10 m depth, and varies slightly in the horizontal direction. The Vs gradually increase to 2000 m/s from 20 m to ~80-100 m in depth, and remains relatively homogeneous in the horizontal direction. This is likely a firn layer and the transition zone. Particle motion analysis reveals potential higher mode Rayleigh waves traveling at a phase velocity of ~2 km/s with little dispersion at ~15-30 Hz, and P-type body wave with an apparent velocity of ~4 km/s around 20 Hz. Updated results will be presented in the meeting.
Session: Single-station Passive Exploration Methods: Status and Perspectives [Poster]
Type: Poster
Date: 4/18/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Lei Qin
Student Presenter: No
Invited Presentation:
Authors
Lei Qin Presenting Author Corresponding Author qinqiu48@163.com China University of Geosciences, Wuhan |
Nori Nakata nnakata@mit.edu Lawrence Berkeley National Laboratory |
Zhendong Zhang zdzhang@mit.edu Massachusetts Institute of Technology |
Hongrui Qiu hongruiqiu@lbl.gov Lawrence Berkeley National Laboratory |
Marianne Karplus mkarplus@utep.edu University of Texas at El Paso |
Galen Kaip gkaip@utep.edu University of Texas at El Paso |
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High-Resolution Imaging of the Firn Layer in Antarctic Near the West Antarctic Ice Sheet Divide Camp
Category
General Session