A new dawn for Australian ocean-bottom seismography

Goncharov, Alexey; Cooper, A.; Chia, Peter; O'Neil, Paul

doi:10.1190/tle35010099.1

Cited by 5 publications

(1 citation statement)

References 2 publications

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“…For stationary-receiver surveys, coarse 3D passive/active-source OBS experiments begin to emerge in academia (Morgan et al, 2016;Goncharov et al, 2016;Heath et al, 2019;Arai et al, 2019). Sparse areal OBS deployments provide the necessary flexibility to design long-offset acquisition geometries, such that energetic diving waves and post-critical reflections could sample the deepest targeted-structures (lower crust, Moho, upper mantle).…”

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confidence: 99%

GO_3D_OBS – The Nankai Trough-inspired benchmark geomodel for seismic imaging methods assessment and next generation 3D surveys design (version 1.0)

Górszczyk

Operto

2020

Preprint

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Abstract. Detailed reconstruction of deep crustal targets by seismic methods remains a long-standing challenge. One key to address this challenge is the joint development of new seismic acquisition systems and leading-edge processing techniques. In marine environments, controlled-source seismic surveys at regional scale are typically carried out with sparse arrays of ocean bottom seismometers (OBSs), which provide incomplete and down-sampled subsurface illumination. To assess and minimize the acquisition footprint in high-resolution imaging process such as full waveform inversion, realistic crustal-scale benchmark models are clearly required.The deficiency of such models prompts us to build one and release it freely to the geophysical community. Here we introduce GO_3D_OBS – a 3D high-resolution geomodel representing a subduction zone, inspired by the geology of the Nankai Trough. The 175 km x 100 km x 30 km model integrates complex geological structures with a visco-elastic isotropic parametrization. It is defined in form of a uniform Cartesian grid containing 33.6e9 degrees of freedom for a grid interval of 25 m. The size of the model raises significant high-performance computing challenges to tackle large-scale forward propagation simulations and related inverse problems. We describe the workflow designed to implement all the model ingredients including 2D structural segments, their projection into the third dimension, stochastic components and physical parametrisation. Various wavefield simulations we present clearly reflect in the seismograms the structural complexity of the model and the footprint of different physical approximations. This benchmark model shall help to optimize the design of next generation 3D academic surveys – in particular but not only long-offset OBS experiments – to mitigate the acquisition footprint during high-resolution imaging of the deep crust.

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confidence: 99%

GO_3D_OBS – The Nankai Trough-inspired benchmark geomodel for seismic imaging methods assessment and next generation 3D surveys design (version 1.0)

Górszczyk

Operto

2020

Preprint

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Australian national ocean bottom seismograph fleet advances conventional exploration

et al. 2017

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A fleet of new Australian ocean bottom seismographs (OBSs) have broadband frequency range, and similar instruments are available at only five or six institutions globally. These OBSs are multi-purpose devices able to record passive-source seismic data (earthquakes, ambient noise) as well as active-source (airgun generated) data and, at the same time, to monitor seismic survey noise and whale calls for environmentally responsible exploration. OBS data collected during commercial seismic surveys in Australian waters prove that it is possible to image the velocity distribution of the whole crust and upper mantle from analysis of both reflected and refracted phases generated by an industry-standard broadband airgun array. This means that valuable information on a regional scale can be obtained as a by-product of commercial seismic surveys. Three-component recording capability of OBSs allows analysis of S-waves in addition to the P-waves that are conventionally used in marine reflection surveys.

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Broad-band ocean bottom seismometer noise properties

Janiszewski

Eilon

Russell

et al. 2022

Geophysical Journal International

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Summary We present a new compilation and analysis of broadband ocean bottom seismometer noise properties from 15 years of seismic deployments. We compile a comprehensive dataset of representative four-component (seismometer and pressure gauge) noise spectra and cross-spectral properties (coherence, phase, and admittance) for 551 unique stations spanning 18 US-led experiments. This is matched with a comprehensive compilation of metadata parameters related to instrumentation and environmental properties for each station. We systematically investigate the similarity of noise spectra by grouping them according to these metadata parameters to determine which factors are the most important in determining noise characteristics. We find evidence for improvements in similarity of noise properties when grouped across parameters, with groupings by seismometer type and deployment water depth yielding the most significant and interpretable results. Instrument design, that is the entire deployed package, also plays an important role, although it strongly covaries with seismometer and water depth. We assess the presence of traditional sources of tilt, compliance, and microseismic noise to characterize their relative role across a variety of commonly used seismic frequency bands. We find that the presence of tilt noise is primarily dependent on the type of seismometer used (covariant with a particular subset of instrument design), that compliance noise follows anticipated relationships with water depth, and that shallow, oceanic shelf environments have systematically different microseism noise properties (which are, in turn, different from instruments deployed in shallow lake environments). These observations have important implications for the viability of commonly used seismic analysis techniques. Finally, we compare spectra and coherences before and after vertical channel tilt and compliance noise removal to evaluate the efficacy and limitations of these now standard processing techniques. These findings may assist in future experiment planning and instrument development, and our newly compiled noise dataset serves as a building block for more targeted future investigations by the marine seismology community.

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A new dawn for Australian ocean-bottom seismography

Cited by 5 publications

References 2 publications

GO_3D_OBS – The Nankai Trough-inspired benchmark geomodel for seismic imaging methods assessment and next generation 3D surveys design (version 1.0)

GO_3D_OBS – The Nankai Trough-inspired benchmark geomodel for seismic imaging methods assessment and next generation 3D surveys design (version 1.0)

Australian national ocean bottom seismograph fleet advances conventional exploration

Broad-band ocean bottom seismometer noise properties

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