A5088664218- Seismic Waves and Analysis
- High-pressure geophysics and materials
- earthquake and tectonic studies
- Seismic Imaging and Inversion Techniques
- Geological and Geochemical Analysis
- Seismology and Earthquake Studies
- Geophysics and Sensor Technology
- Geological and Geophysical Studies
- Earthquake Detection and Analysis
- Geophysical Methods and Applications
- Ultrasonics and Acoustic Wave Propagation
- Geological Modeling and Analysis
- Geochemistry and Geologic Mapping
- Geophysical and Geoelectrical Methods
- Underwater Acoustics Research
- Drilling and Well Engineering
- Hydraulic Fracturing and Reservoir Analysis
- Methane Hydrates and Related Phenomena
- Advanced Fiber Optic Sensors
- Geophysics and Gravity Measurements
- Numerical methods in inverse problems
- Numerical methods in engineering
- Reservoir Engineering and Simulation Methods
- Landslides and related hazards
- Geomagnetism and Paleomagnetism Studies
Australian National University
2016-2025
Wake Forest University
2016
Atrium Health Wake Forest Baptist
2016
Academia Sinica
2014
Canberra (United Kingdom)
2013
University of Cambridge
1977-2008
Bandung Institute of Technology
1998
Massachusetts Institute of Technology
1998
Utrecht University
1989
Physics, Materials and Applied Mathematics Research (United States)
1983
Over the last three years, a major international effort has been made by Sub-Commission on Earthquake Algorithms of International Association Seismology and Physics Earth's Interior (IASPEI) to generate new global traveltime tables for seismic phases update Jeffreys & Bullen (1940). The are specifically designed convenient computational use, with high-accuracy interpolation in both depth range. iasp91 derived from radially stratified velocity model which constructed so that times consistent...
New empirical traveltime curves for the major seismic phases have been derived from catalogues of International Seismological Centre by relocating events using P readings, depth and iasp91 traveltimes, then re-associating phase picks. A smoothed set tables is extracted a robust procedure which gives estimates variance traveltimes each branch. This times used to construct range radial velocity profiles, are assessed against number different measures level fit between predictions models. These...
The response of a stratified elastic half space to general source may be represented in terms the reflection and transmission properties regions above below source. For P-SV SH waves both buried sources receivers, convenient forms found which no loss precision problems arise from growing exponential evanescent regime. These expressions have ready physical interpretation enable useful approximations developed. representation leads efficient computational procedures for models composed uniform...
Reference earth models can be retrieved from either body waves or normal-mode eigenperiods. However, there is a large discrepancy between different reference models, which arises partly the type of data set used in their construction and differences parametrization. derived body-wave observations do not give access to density, attenuation factor radial anisotropy. Conversely, normal modes cannot provide correct locations for depth seismic discontinuities, nor associated velocity jump....
We present a full seismic waveform tomography for upper-mantle structure in the Australasian region. Our method is based on spectral-element simulations of wave propagation 3-D heterogeneous earth models. The accurate solution forward problem ensures that misfits are solely due to as yet undiscovered Earth and imprecise source descriptions, thus leading more realistic tomographic images parameter estimates. To reduce computational costs, we implement long-wavelength equivalent crustal model....
abstract The connection is established between conventional matrix methods for layered media and the reflection transmission properties of a single layer. This interrelation then used to set up an iterative approach calculation coefficients in multilayered media. lends itself ray interpretation allows estimates errors involved taking truncated partial expansions be made. special effects due free surface are also considered.
Most nonlinear inverse problems can be cast into the form of determining minimum a misfit functional model parameters. This determines between observations and corresponding theoretical predictions, subject to some regularization conditions on model. When there is only one type parameter in model, methods based gradient techniques work well, especially when information rate change gradients included. In case depending multiparameter classes, simple mix parameters different character physical...
We propose a new approach to full seismic waveform inversion on continental and global scales. This is based the time–frequency transform of both data synthetic seismograms with use time- frequency-dependent phase envelope misfits. These misfits allow us provide complete quantification differences between synthetics while separating amplitude information. The result an efficient exploitation information that robust quasi-linearly related Earth's structure. Thus, are usable for continental-...
High‐quality P and S travel times are now available from careful reprocessing of data reported to international agencies. A restricted set has been extracted for which comparable ray coverage is achieved , used a joint inversion produce three‐dimensional model shear bulk sound velocities represented in terms 2° × cells 18 layers depth through the mantle. About 10 6 each combined 312,549 summary rays wave type. Linearizing about ak135 reference model, 583,200 coupled tomographic equations...
Genetic algorithm (GA) inversion, a nonlinear global optimization technique, has been applied to determine crustal and uppermost mantle velocity structure from teleseismic receiver functions. With new modelling in which not only the S wave but also layer thickness V P /V ratio are model parameters, GA function inversion is able recover with reasonable accuracy whole crust, particularly well for surface crust‐mantle boundary. Structural functions network of broadband seismic stations eastern...
Abstract The propagation of Lg waves in complex media can be described either by means a modal superposition scheme with numerical integration through the heterogeneity or using ray diagrams. Rays are set off at equal horizontal intervals stratified zone adjacent to heterogeneity, phase velocities appropriate particular modes. constructive interference pattern medium is modified horizontally varying region give graphic illustration effects. method agrees well calculations but may...
Three seismic refraction profiles have been recorded on the East Pacific Rise near Siqueiros fracture zone. These interpreted using both travel-time analysis and waveform amplitude studies with aid of synthetic seismograms. For profile at Crest a pronounced low velocity zone has found about 2 km below seabed. The P-wave velocities increase quite rapidly from 5 s-1 sea floor to 6·7 lid Mantle arrivals this indicate 7·7 s-1. A second profile, 2·9 My old crust shows shallow region strong...
Since 2004 more than 7000 km of full-crustal reflection profiles have been collected across Australia to give a total 11 000 km, providing valuable new constraints on crustal structure. A further set hitherto unexploited results comes from 150 receiver functions distributed the continent, mostly portable sites. These data sets provide dramatic increase in coverage compared with previous studies, and reveal complex structure Australian continent considerable detail. comprehensive model for...
The propagation of surface waves in a laterally varying medium can be described by representing the wavetrain as superposition modal contributions for reference structure. As guided propagate through heterogeneous zone coefficients needed to describe vary with position, leading interconversions between modes and reflection into backward travelling modes. evolution terms may set first-order differential equations which allow coupling both forward waves; these depend on differences actual...
AbstractA 581 km vibroseis-source, deep seismic reflection survey was acquired through the Capricorn Orogen of Western Australia and, for first time, provides an unprecedented view crustal architecture West Australian Craton. The has imaged three principal suture zones, as well several other lithospheric-scale faults. zones separate four seismically distinct tectonic blocks, which include Pilbara Craton, Bandee Seismic Province (a previously unrecognised block), Glenburgh Terrane Gascoyne...
Surface wave tomography for Australian crustal structure has been carried out using group velocity measurements in the period range 1–32 s extracted from stacked correlations of ambient noise between station pairs. Both Rayleigh and Love maps are constructed each vertical transverse component Green's function estimates noise. The full suite portable broadband deployments permanent stations on continent have used with over 250 all up to 7500 paths. provide a useful link various shorter‐term...
The mantle component of the Australian Seismological Reference Model (AuSREM) has been constructed from Australian-specific sources, primarily exploiting wealth seismic sources at regional distances around Australia recorded portable and permanent stations on continent. AuSREM is designed to bring together existing information Australia, both body wave surface studies provide a synthesis in form 3-D model that can basis for future refinement. grid based with 0.5° sampling latitude longitude,...
Ice streams are major regulators of sea level change. However, standard viscous flow simulations their evolution have limited predictive power due to incomplete understanding involved processes. On the Greenland ice sheet, borehole fiber-optic observations reveal a brittle deformation mode that is incompatible with over length scales similar resolution modern sheet models: englacial quake cascades unobservable at surface. Nucleating near volcanism-related impurities promote grain boundary...
We present a new three‐dimensional model for the SV wave hetero‐geneities and azimuthal anisotropy in upper mantle of Australasian region. The is constrained by waveforms 2194 Rayleigh waves seismograms with dense ray coverage that ensure lateral resolution order few hundred kilometers. use higher modes allows structure down to depths at least 400 km. In 200 km model, seismic velocities are lower on eastern Phanerozoic margin continent compared Precambrian central western cratons, agreement...