ORCID Profile
0000-0001-9187-3138
Current Organisation
Australian National University
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Seismology and Seismic Exploration | Geophysics | Natural Hazards | Ocean Engineering | Marine Geoscience | Tectonics
Natural Hazards in Sparseland, Permanent Grassland and Arid Zone Environments | Expanding Knowledge in the Earth Sciences | Natural Hazards in Mining Environments | Mineral Exploration not elsewhere classified | Natural Hazards in Antarctic and Sub-Antarctic Environments |
Publisher: Oxford University Press (OUP)
Date: 31-07-2022
DOI: 10.1093/GJI/GGAC294
Abstract: A blanket of sedimentary and regolith material covers approximately three-quarters of the Australian continent, obscuring the crustal geology below and potential mineral resources within. Sedimentary basins also trap seismic energy increasing seismic hazard and generating noisy seismograms that make determining deeper crustal and lithospheric structure more challenging. The most fundamental question that can first be asked in addressing these challenges is how thick are the sediments? Borehole drilling and active seismic experiments using a controlled seismic source (e.g. vibroseis) provide excellent constraints, but they are limited in geographical coverage due to their expense, especially when operating in remote areas. On the other hand, passive-seismic experiments that involve the deployment of seismic receivers only (i.e. seismometers) are relatively low-cost and portable, providing a practical alternative for initial surveys. Here we utilize receiver functions obtained for both temporary and permanent seismic stations in South Australia, covering regions with a erse sediment distribution. We present a straightforward method to determine the basement depth based on the arrival time of the P-converted-to-S phase generated at the boundary between the crustal basement and sedimentary strata above. Utilizing the available borehole data, we establish a simple predictive relationship between Ps arrival time and the basement depth, which could then be applied to other sedimentary basins with some consideration. The method is found to work best for Phanerozoic sediments and offers a way to determine the sediment–basement interface in unexplored areas requiring only temporary seismic stations deployed for & 6 months.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Mary Ann Liebert Inc
Date: 15-01-2018
Abstract: The EPO-TBI study randomized 606 patients with moderate or severe traumatic brain injury (TBI) to be treated with weekly epoetin alfa (EPO) or placebo. Six month mortality was lower in EPO treated patients in an analysis adjusting for TBI severity. Knowledge of possible differential effects by TBI injury subtype and acute neurosurgical treatment as well as timing and cause of death (COD) will facilitate the design of future interventional TBI trials. We defined COD as cerebral (brain death, cerebral death with withdrawal, or death during maximal care) and non-cerebral (death following withdrawal or during maximal care, which had a non-cerebral cause). The study included 305 patients treated with EPO and 297 treated with placebo, with COD recorded in 77 (99%) out of 78 non-survivors. Median time to death in patients dying of cerebral COD was 8 days (interquartile range [IQR] 5-16) compared with 29 days (IQR 7-56) (p = 0.01) for non-cerebral COD. When assessing subgroups by admission CT scan injury findings, we found no significant differential effects of EPO compared with placebo. However, EPO appeared more effective in patients with an injury type not requiring a neurosurgical operation prior to intensive care unit (ICU) admission (odds ratio [OR] 0.29, 95% confidence interval [CI] 0.14-0.61, p = 0.001, p for interaction = 0.003) and in this subgroup, fewer patients died of cerebral causes in the EPO than in the placebo group (5% compared with 14%, p = 0.03). In conclusion, most TBI deaths were from cerebral causes that occurred during the first 2 weeks, and were related to withdrawal of care. EPO appeared to specifically reduce cerebral deaths in the important subgroup of patients with a diffuse type of injury not requiring a neurosurgical intervention prior to randomization.
Publisher: Massachusetts Medical Society
Date: 03-2018
Publisher: Elsevier BV
Date: 12-2021
Publisher: American Geophysical Union (AGU)
Date: 23-05-2014
DOI: 10.1002/2014GL059943
Publisher: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 09-2010
Publisher: Elsevier BV
Date: 02-2015
Publisher: Research Square Platform LLC
Date: 07-2021
DOI: 10.21203/RS.3.RS-121788/V2
Abstract: The Australian continental crust preserves a rich geological history, but it is unclear to what extent this history is expressed deeper within the mantle. Scattering of surface waves predominantly between 100-200 km depth by lateral gradients in seismic anisotropy, termed Quasi-Love waves, offer potential new insights. Across Australasia over 275 new scatterers are detected, and are found to be preferentially located near (1) the passive continental margins, and (2) the boundaries of major geological provinces within Australia. Such lateral anisotropic gradients imply pervasive fossilized lithospheric anisotropy within the continental interior, on a scale that mirrors the crustal geology at the surface, and a strong lithosphere that preserves this signal over billions of years. Along the continental margins, lateral anisotropic gradients may indicate either the edge of the thick continental lithosphere, or small-scale dynamic processes in the asthenosphere, such as edge-drive convection, tied to the transition from oceanic to continental lithosphere.
Publisher: Informa UK Limited
Date: 11-11-2019
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-2108
Abstract: & & Australia is an old stable continent with a rich geological history. Limitations in sub-surface seismic imaging below the Moho, however, mean that is unclear to what extent, and to what depth, this rich geological history is expressed in the mantle. Studies of seismic anisotropy, which reflect past resent mantle deformation, can offer potential insights. One commonly employed technique is shear wave splitting, in which the wave polarisation is measured. New such results from seismic arrays deployed across central Australia, reveal a pattern of anisotropy that is consistent with past deformation of the Australian lithosphere that has been preserved for over 300 million years. Another informative technique is to use scattered surface waves, called Quasi-Love waves, that can detect lateral gradients in seismic anisotropy. The first such study for the region finds that scatterers are preferentially located near (1) the passive continental margins, and (2) the boundaries of major geological provinces within Australia. Such lateral anisotropic gradients within the continental interior imply pervasive fossilized lithospheric anisotropy, on a scale that mirrors the crustal geology at the surface. Beneath the continental margins, lateral anisotropic gradients may indicate small-scale dynamic processes in the asthenosphere, such as edge-drive convection, that are tied to the margins.& &
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-6846
Abstract: & & The Australian continent, being void of plate boundaries, is often perceived as seismically quiescent. However, around 100 magnitude three or larger earthquakes are typically recorded in Australia each year, with a magnitude 6+ occurring every 8-10 years. Such intra-plate activity can pose a significant risk as they are often non-periodic, poorly understood, and sporadically recorded by sparse seismic networks across vast continents. Within Australia the distribution of intra-plate seismicity is non-uniform, but instead tends to concentrate along certain weak zones of increased activity. One such region is the eastern margin of the Gawler Craton in South Australia, one of the oldest building blocks of the continent. Recently several new temporary seismic arrays have been deployed in the region, transforming data coverage across South Australia. So far over 70 new local events have been recorded that would otherwise have gone undetected by the national network. After relocation the pattern of earthquakes becomes more spatially defined and appears to be closely tied to the edge of the Gawler Craton. Supporting evidence suggests that these events may be associated with a trans-crustal scale fault system that adds new constraints on the poorly defined craton boundary.& &
Publisher: American Geophysical Union (AGU)
Date: 09-2013
DOI: 10.1002/JGRB.50349
Publisher: Research Square Platform LLC
Date: 27-01-2021
DOI: 10.21203/RS.3.RS-121788/V1
Abstract: Australia is an old stable continent with a rich geological history. Limitations in sub-surface imaging below the Moho, however, mean that is unclear to what extent, and to what depth, this rich geological history is expressed in the mantle. Scattering of surface waves at ~150km depth by lateral gradients or boundaries in seismic anisotropy, termed Quasi-Love waves, offer potential new insights. The first such analysis for Australia and Zealandia shown here detects over 300 new scatterers that display striking geographical patterns. Around two-thirds of the scatterers are coincident with either the continental margins, or major crustal boundaries within Australia, suggesting deep mantle roots to such features. Within the continental interior such lateral anisotropic gradients imply pervasive fossilized lithospheric anisotropy, on a scale that mirrors the crustal geology at the surface, and a strong lithosphere that preserves this signal over billions of years. Along the continental margins, lateral anisotropic gradients may indicate either the edge of the thick continental lithosphere, or small-scale dynamic processes in the asthenosphere, such as edge-drive convection, tied to the transition from oceanic to continental crust/lithosphere.
Publisher: Springer Science and Business Media LLC
Date: 09-01-2017
Publisher: American Geophysical Union (AGU)
Date: 08-2019
DOI: 10.1029/2019GC008433
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-10662
Abstract: The Macquarie Ridge Complex, located at the boundary between Indo-Australian and Pacific plates in the southwest Pacific Ocean, hosts the largest sub-marine earthquakes in the 20th century, not associated with ongoing subduction. We deployed 27 ocean-bottom seismometers, of which 15 have been recovered successfully, to understand the origin of the sub-marine earthquakes and their potential earthquake and tsunami hazards to Australia and New Zealand. Additionally, we deployed five land-based seismometers on Macquarie Island.We explore state-of-the-art processing methods to analyze the new seismic dataset from the retrieved seismic stations. One of the goals is to image the tectonic settings beneath the MRC. Here, we present a first-order tomographic model and its relevant uncertainty estimate of the region constructed from ambient noise surface waves using a probabilistic inversion framework. The tomographic image will be complemented with receiver-based imaging results such as those from P-wave coda autocorrelations and receiver functions to confirm the existence of possible geometries. The results are expected to supply a fresh understanding of the tectonic settings under the MRC and unpuzzle the origin of the significant underwater earthquakes in the 20th century.
Publisher: Oxford University Press (OUP)
Date: 28-01-2023
DOI: 10.1093/GJI/GGAD035
Abstract: In recent years, there has been a considerable expansion of deployments of portable seismic stations across Australia, which have been analysed by receiver function or autocorrelation methods to extract estimates of Moho depth. An ongoing program of full-crustal reflection profiles has now provided more than 25 000 km of reflection transects that have been interpreted for Moho structure. The Moho data set is further augmented by extensive marine reflection results. These new data sources have been combined with earlier refraction and receiver function results to provide full continental coverage, though some desert areas remain with limited s ling. The dense s ling of the Moho indicates the presence of rapid changes in Moho depth, and so, the Moho surface has been constructed using an approach that allows different weighting and spatial influence depending on the nature of the estimate. The inclusion of Moho results from continental-wide gravity inversion with low weighting helps to resolve the continent-ocean transition and to provide additional control in the least s led zones. The refined distribution indicates the presence of widespread smaller-scale variations in Moho structure. Strong lateral contrasts in crustal thickness remain, but some have become more subdued with improved s ling of critical areas. The main differences from earlier results lie in previously poorly s led regions around the Lake Eyre Basin, where additional passive seismic results indicate somewhat thicker crust though still with a strong contrast in crustal thickness to the cratonic zone to the west.
Publisher: Authorea, Inc.
Date: 08-07-2023
DOI: 10.22541/ESSOAR.168881742.29827772/V1
Abstract: Rapid plate motion, alongside pronounced variations in age and thickness of the Australian continental lithosphere, make it an excellent location to assess the relationship between seismic anisotropy and lithosphere-asthenosphere dynamics. In this study, SKS and PKS shear-wave splitting is conducted for 176 stations covering the transition from the South Australian Craton to eastern Phanerozoic Australia. Comparisons are made with models of lithospheric thickness as well as numerical simulations of mantle flow. Splitting results show uniform ENE-WSW aligned fast directions over the Gawler Craton and broader South Australian Craton, similar to the orientation of crustal structures generated during an episode of NW-SE directed compression and volcanism ~1.6 billion years ago. We propose that heat from volcanism weakened the lithosphere, aiding widespread lithospheric deformation, which has since been preserved in the form of frozen-in anisotropy. Conversely, over eastern Phanerozoic Australia, fast directions show strong alignment with the NNE absolute plate motion. Overall, our results suggest that when the lithosphere is thin ( km), lithospheric contributions are minimal and contributions from asthenospheric anisotropy dominate, reflecting shear of the underlying mantle by Australia’s rapid plate motion above. Further insights from geodynamical simulations of the regional mantle flow-field, which incorporate Australian and adjacent upper mantle structure, predict that asthenospheric material would be drawn in from the south and east towards the fast-moving continental keel. Such a mechanism, alongside interactions between the flow field and lithospheric structure, provides a plausible explanation for smaller-scale anomalous splitting patterns beneath eastern Australia that do not align with plate motion.
Publisher: American Geophysical Union (AGU)
Date: 30-05-2020
DOI: 10.1029/2019JB018438
Publisher: Elsevier BV
Date: 03-2021
Publisher: Wiley
Date: 19-07-2022
Publisher: Springer Science and Business Media LLC
Date: 04-10-2021
DOI: 10.1038/S43247-021-00276-7
Abstract: The Australian continental crust preserves a rich geological history, but it is unclear to what extent this history is expressed deeper within the mantle. Here an investigation of Quasi-Love waves is performed to detect scattering of seismic surface waves at mantle depths (between 100–200 km) by lateral gradients in seismic anisotropy. Across Australasia 275 new observations of Quasi-Love waves are presented. The inferred scattering source and lateral anisotropic gradients are preferentially located either near the passive continental margins, or near the boundaries of major geological provinces within Australia. Pervasive fossilized lithospheric anisotropy within the continental interior is implied, on a scale that mirrors the crustal geology at the surface, and a strong lithosphere that has preserved this signal over billions of years. Along the continental margins, lateral anisotropic gradients may indicate either the edge of the thick continental lithosphere, or small-scale dynamic processes in the asthenosphere below.
Publisher: Wiley
Date: 10-2021
Publisher: American Geophysical Union (AGU)
Date: 03-2013
DOI: 10.1002/JGRB.50092
Publisher: American Geophysical Union (AGU)
Date: 03-06-2020
DOI: 10.1029/2020GL087398
Publisher: American Geophysical Union (AGU)
Date: 07-2016
DOI: 10.1002/2016GC006316
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-6878
Abstract: & & & & & & & & A blanket of sedimentary and regolith material covers approximately three-quarters of the Australian continent, obscuring the crustal geology below and potential mineral resources within. Sedimentary basins also trap seismic energy increasing seismic hazard and generating noisy seismograms that make determining deeper crustal and lithospheric structure more challenging. The most fundamental question that can first be asked in addressing these challenges is how thick are the sediments? Borehole drilling and active seismic experiments provide excellent constraints, but they are limited in geographical coverage due to their expense, especially when operating in remote areas. On the other hand, passive-seismic deployments are relatively low-cost and portable, providing a practical alternative for initial surveys. Here we utilize receiver functions obtained for both temporary and permanent seismic stations in South Australia, covering regions with a erse sediment distribution. We present a straightforward method to determine the basement depth based on the arrival time of the P-converted-to-S phase generated at the boundary between the crustal basement and sedimentary strata above. Utilizing the available borehole data, we establish a simple predictive relationship between Ps arrival time and the basement depth, which could then be applied to other sedimentary basins with some consideration. The method is found to work best for Phanerozoic sediments and& offers a way to determine the sediment-basement interface in unexplored areas requiring only temporary seismic stations deployed for & 6 months.& & & & & img src=& quot ileStorageProxy.php?f=gnp.fa7d61877ed167359691461/sdaolpUECMynit/22UGE& app=m& a=0& c=82b85d02d2969cb9185a9774fa7c48d1& ct=x& n=gnp.elif& d=1& quot alt=& quot & quot width=& quot & quot height=& quot & quot & & & & / & & / & & / &
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-10875
Abstract: The Macquarie Ridge Complex (MRC) constitutes the boundary between the Indo-Australian and Pacific plates in the southwest Pacific Ocean. It accommodates the world& #8217 s most potent sub-marine earthquakes that are not associated with ongoing subduction. To better understand the nature of MRC and its associated earthquakes, we aim to explore the crustal structures using recordings from island-based stations and ocean bottom seismometers (OBS). In particular, these OBSs, which are deployed in the surroundings of Macquarie Island from October 2020 to November 2021, enable us to image the refined oceanic structures beneath the study area. In this study, we obtain the body-wave reflections by computing phase coherence autocorrelations of both ambient noise and earthquake data. Our preliminary reflection profiles by both methods reveal coherent reflected P waves that may be related to Moho and additional structures within the crust and upper mantle.
Publisher: Springer Science and Business Media LLC
Date: 15-03-2018
Publisher: American Geophysical Union (AGU)
Date: 09-2023
DOI: 10.1029/2023GC011066
Publisher: American Geophysical Union (AGU)
Date: 14-06-2021
DOI: 10.1029/2021EO159537
Abstract: Our crew braved rough Southern Ocean seas, endured pandemic precautions, and adapted plans on the fly for the chance to observe a possible subduction zone in the making below the Macquarie Ridge.
Publisher: Geological Society of London
Date: 2011
DOI: 10.1144/SP356.12
Publisher: Elsevier BV
Date: 09-2023
Publisher: American Geophysical Union (AGU)
Date: 02-2018
DOI: 10.1002/2017JB015176
Publisher: Elsevier BV
Date: 10-2014
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-6989
Abstract: & & Australia is an old stable continent with a rich geological history. Limitations in sub-surface imaging below the Moho, however, mean that is unclear to what extent, and to what depth, this rich geological history is expressed in the mantle. Scattering of surface waves at ~150km depth by lateral gradients or boundaries in seismic anisotropy, termed Quasi-Love waves, offer potential new insights. The first such analysis for Australia and Zealandia is performed with over 300 new scatterers detected that display striking geographical patterns. Around two-thirds of the scatterers are coincident with either the continental margins, or major crustal boundaries within Australia, suggesting deep mantle roots to such features. Within the continental interior such lateral anisotropic gradients imply pervasive fossilized lithospheric anisotropy, on a scale that mirrors the crustal geology at the surface, and a strong lithosphere that preserves this signal over billions of years. Along the continental margins, lateral anisotropic gradients may indicate either the edge of the thick continental lithosphere, or small-scale dynamic processes in the asthenosphere, such as edge-drive convection, tied to the transition from oceanic to continental crust/lithosphere.& &
Publisher: Springer Science and Business Media LLC
Date: 16-09-2019
Publisher: Springer Science and Business Media LLC
Date: 27-07-2020
DOI: 10.1038/S41467-020-17522-9
Abstract: Subduction zones are pivotal for the recycling of Earth’s outer layer into its interior. However, the conditions under which new subduction zones initiate are enigmatic. Here, we constructed a transdisciplinary database featuring detailed analysis of more than a dozen documented subduction zone initiation events from the last hundred million years. Our initial findings reveal that horizontally forced subduction zone initiation is dominant over the last 100 Ma, and that most initiation events are proximal to pre-existing subduction zones. The SZI Database is expandable to facilitate access to the most current understanding of subduction zone initiation as research progresses, providing a community platform that establishes a common language to sharpen discussion across the Earth Science community.
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2023
End Date: 2026
Funder: Cooperative Research Centres, Australian Government Department of Industry
View Funded ActivityStart Date: 2020
End Date: 2022
Funder: Australian Research Council
View Funded ActivityStart Date: 2019
End Date: 2021
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2019
End Date: 02-2023
Amount: $404,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2020
End Date: 12-2023
Amount: $626,000.00
Funder: Australian Research Council
View Funded Activity