Authors / CoAuthors
Hejrani, B.
Abstract
<div>As part of the first phase (2016-2020) of the Exploring for the Future (EFTF) program, Geoscience Australia deployed 119 broad band seismic stations in northern Australia. This deployment was part of the Australian Passive Seismic Array (AusArray) Project. Data from these stations were used to image the seismic structure using various techniques, including ambient noise tomography (ANT). The first ANT model (Hejrani et al, 2020) was focused on a narrow range of frequencies and used the Hawkins and Sambridge (2019) approach to estimate dispersion curves. This new approach starts from the original work by Aki (1957) to estimate phase velocity in the frequency domain, and then takes a step further to ensure a smooth curve is achieved. In Hejrani et al., (2022), using minimum Signal-to-Noise-Ratio (SNR) threshold of 2, about 4,000 data points (out of 7,000+) were used to generate surface wave velocity maps at a resolution of 1 degree at four frequencies (sensitive to different depths). This model was subsequently updated in September 2021 by using all 7,000+ data points (no SNR threshold) of phase velocity measurements across AusArray year one to provide a 0.25 degree resolution model. All dispersion curves regardless of their quality were utilized. A number of artefacts were identified in that model, which motivated further investigations. During 2022, I developed a new automated and scalable approach to estimate dispersion curves, which was completed in December 2022. This new method starts from the original idea by Aki (1957), but takes a different approach to stabilize the dispersion curves and to avoid cycle skipping. </div><div>This record represents the preferred 2D velocity models for AusArray year one data based on the newly estimated dispersion curves and a comparison with previous models and interpretations; is an update from Hejrani et al. (2020) and should be read in conjunction. Work is currently under way to invert these 2D surface wave models to obtain 3D velocity models for the crust and mantle. Such 3D velocity models would be suitable for joint interpretations with other data such active seismic, gravity and magnetic. The code will be made publicly available at the conclusion of EFTF.</div>
Product Type
document
eCat Id
148676
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Keywords
- ( Project )
-
- EFTF – Exploring for the Future
- ( Project )
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- Australia’s Resources Framework
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- Seismology
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- Ambient Noise Tomography
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- AusArray
- theme.ANZRC Fields of Research.rdf
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- Seismology and Seismic Exploration
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- Published_External
Publication Date
2023-08-09T02:56:02
Creation Date
2023-08-05T12:00:00
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Status
completed
Purpose
This document presents an update on the EFTF extended abstract. This document represents the results of a new approach for automatic picking of dispersion curves. This is a method developed at Geoscience Australia. The results of this approach on AusArray year one data are compared with two other approaches to dispersion curves.
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geoscientificInformation
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<div>This is a document that represents a new method for automatic picking of dispersion curves and present an example for AusArray year 1 data. </div><div>Surface wave tomography maps are presented based on the estimated dispersion curves. </div><div>A comparison is presented for the dispersion curves and the surface wave maps with two other approaches. </div><div>This is an update for the EFTF extended abstract titled: Ambient Noise Tomography of Australia: application to AusArray deployment, with eCat record 135130. </div><div>The eCat record 135130 contains the Extended abstract and a model based on Hawkins and Sambridge (2019) method for picking dispersion curve. </div><div>The model in the eCat record 135130 is superseded by the model presented with this document. </div>
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[-54.75, -9.2402, 112.92, 159.11]
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Associations
Association Type - crossReference
Ambient noise tomography of Australia: application to AusArray deployment
eCat Identifier - 135130,
UUID - 97cda114-ff90-45b2-9fda-97fe319cc191
Association Type - operatedOnBy
National Geophysical Grids WMS
eCat Identifier - 140126,
UUID - 9bac39d0-827c-4ca8-9f15-f99c1c201b64
Association Type - operatedOnBy
National Geophysical Grids WCS
eCat Identifier - 146015,
UUID - e49f3b62-01c3-474c-b731-ad35c69fe72d
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