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Full wavefield decomposition of high-frequency secondary microseisms reveals distinct arrival azimuths for Rayleigh and Love waves
Citation
Gal, M and Reading, AM and Ellingsen, SP and Koper, KD and Burlacu, R, Full wavefield decomposition of high-frequency secondary microseisms reveals distinct arrival azimuths for Rayleigh and Love waves, Journal of Geophysical Research: Solid Earth, 122, (6) pp. 4660-4675. ISSN 2169-9313 (2017) [Refereed Article]
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Copyright Statement
© 2017. American Geophysical Union.
Abstract
In the secondary microseism band (0.1–1.0 Hz) the theoretical excitation of Rayleigh waves (Rg/LR), through oceanic wave-wave interaction, is well understood. For Love waves (LQ), the excitation mechanism in the secondary microseism band is less clear. We explore high-frequency secondary microseism excitation between 0.35 and 1 Hz by analyzing a full year (2013) of records from a three-component seismic array in Pilbara (PSAR), Australia. Our recently developed three-component waveform decomposition algorithm (CLEAN-3C) fully decomposes the beam power in slowness space into multiple point sources. This method allows for a directionally dependent power estimation for all separable wave phases. In this contribution, we compare quantitatively microseismic energy recorded on vertical and transverse components. We find the mean power representation of Rayleigh and Love waves to have differing azimuthal distributions, which are likely a result of their respective generation mechanisms. Rayleigh waves show correlation with convex coastlines, while Love waves correlate with seafloor sedimentary basins. The observations are compared to the WAVEWATCH III ocean model, implemented at the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), which describes the spatial and temporal characteristics of microseismic source excitation. We find Love wave energy to originate from raypaths coinciding with seafloor sedimentary basins where strong Rayleigh wave excitation is predicted by the ocean model. The total power of Rg waves is found to dominate at 0.35–0.6 Hz, and the Rayleigh/Love wave power ratio strongly varies with direction and frequency.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | microseisms, wavefield, Rayleigh Waves, Love Waves |
| Research Division: | Earth Sciences |
| Research Group: | Geophysics |
| Research Field: | Seismology and seismic exploration |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the earth sciences |
| UTAS Author: | Gal, M (Mr Martin Gal) |
| UTAS Author: | Reading, AM (Professor Anya Reading) |
| UTAS Author: | Ellingsen, SP (Professor Simon Ellingsen) |
| ID Code: | 120182 |
| Year Published: | 2017 |
| Funding Support: | Australian Research Council (DP150101005) |
| Web of Science® Times Cited: | 10 |
| Deposited By: | Earth Sciences |
| Deposited On: | 2017-08-14 |
| Last Modified: | 2018-04-26 |
| Downloads: | 178 View Download Statistics |
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