Chercheurs

Sciences de la Terre / KENNETT, BRIAN L.N.

brian

Position

Director and Professor of Seismology
Director, ANSIR National Research Facility
Research School of Earth Sciences,
Australian National University
Canberra, Australia

Past President, International Association of Seismology and Physics of the Earth's Interior (IASPEI)

Thèmes de recherche

The development of interpretational techniques for seismic records, with the object of extracting detailed information about the nature of the structure within the Earth, and the character of seismic sources.

a) The Structure of the Earth

* Structure of the Upper Mantle

o Velocity and attenuation structure from refracted body waves
o Nature of heterogeneity in upper mantle
+ Pervasive presence of medium-scale heterogeneity
+ 3-D structure in transition zone beneath Australian region
+ exploiting velocities, attenuation, anisotropy
o Development of systematic studies of a Australian region using arrays of portable broad-band instruments
# SKIPPY experiment 1993-1996 - whole continent
# KIMBA 1997-1998 more detailed experiment in Kimberley WA
# QUOLL 1999 - south-eastern Australia
+ surface wave tomography
+ body wave studies
+ attenuation (body wave and surface waves)
+ anisotropy (SKS splitting, direct S and surface waves
+ receiver function studies

* Structure of whole Earth

o 1-dimensional Earth models from travel times
+ iasp91 - improved earthquake locations and hence empirical travel times
+ ak135 - fit to a wide range of empirical travel times, improved core model and S model
+ have formed the reference models for recent high-resolution travel- time tomography
+ allowed the exploitation of S wave times for tomography (by eliminating baseline discrepancy in earlier models)
o 3-dimensional hear wavespeed variation
+ combining S and SKS information to provide better resolution of lower mantle
o 3-dimensional variation of bulk-sound and shear wavespeeds
+ exploit data set with common source/receiver for both P and S about 1 million times for each exploiting together to produce 3-D images of variation of bulk-sound and shear velocities.
+ The combination of two wavespeed imagesallows the delineation of different heterogeneity regimes
o Relation of Seismic Structure and underlying processes

b) Seismic Wave Propagation

* Systematic treatment of stratified media
o Development of a representation of the seismic wavefield which is both physically based and numerically stable
o Approximations to seismic response tuned to different classes of seismic phases
o Forms basis of most work on anisotropic stratification

* Operator development for heterogeneous media
o Extension of stratified media techniques via operators
o Representations through coupled wavenumbers
o Stochastic wave propagation

* Guided waves in heterogeneous media
o Coupled mode techniques for surface waves in varying waveguides including transmission and reflection (2-D)
o Synthetic seismograms for transmission through heterogeneous regions applied to analysis of surface wave tomography
o Coupled mode and plane wave method for description of surface in 3-D varying media

c) Inverse Theory

Nearly all seismic observations are indirect and the properties of the interior of the Earth have to be deduced from analysis of extensive data sets with relatively subtle dependence on the distribution of seismic wave velocities. There is therefore a major need to develop improved algorithms for the solution of such 'inverse problems'.

* Development of methods for multi-parameter inverse problems

o Application of subspace expansion techniques to geophysical problems
o Dual wavespeed tomography (bulk-sound and shear from P and S times)

* Earthquake location

o Nonlinear methods for earthquake location exploiting multi-phase information.

d) Applied Seismology:

* Discrimination of underground nuclear explosions re Comprehensive Test Ban Treaty

o the iasp91 travel times have been adopted as the standard for event location in the International Data Centre for the Comprehensive Test Ban Treaty
o a shift to ak135 to improve later phases is under discussion
o studies of the regional wavefield and the influence of lateral heterogeneity
o improved regional discriminants incorporating corrections for the influence of the free surface
o techniques for characterising later seismic phases, using arrays or single stations, to improve location accuracy

* Reflection Seismology

o Techniques for multiple suppression for multi-component land records
o The importance of the shear wavespeed in marine work with hard seafloor
o Techniques for processing deep-crustal reflection profiles

Prix et récompenses

1972 : University of Cambridge Smith's Prize, for original essay on "The Scattering of Seismic Waves"

1979 : Van Weelden Award of the European Association of Exploration Geophysicists for paper "The suppression of surface multiples on seismic records" presented at Dublin, June 1978

1981 : University of Cambridge Adam's Prize for essay "Seismic Wave Propagation in Stratified Media"

1988 : Fellow, American Geophysical Union

1994 : Fellow, Australian Academy of Sciences

1996 : Associate, Royal Astronomical Society

2003 : Centenary Medal, Commonwealth of Australia
for "Service to Australian society and science in geophysics"

2005 : Jaeger Medal for Australian Earth Sciences, Australian Academy of Sciences

2005 : Fellow, Royal Society (London)

2006 : Murchison Medal, The Geological Society of London

Publications

Books

Kennett B.L.N. (1983), Seismic Wave Propagation in Stratified Media, pp x+342, Cambridge University Press.

Kennett B.L.N. (1991), IASPEI 1991 Seismological Tables, pp vii+167, Research School of Earth Sciences, ANU (compiler & editor), distributed by Bibliotech, Canberra.

Kennett B.L.N. (1998), Seismic Wave Propagation and Seismic Tomography, pp vi+116, Research School of Earth Sciences, ANU (ISBN 0-7315-3304-6)

Kennett B.L.N., The Seismic Wavefield
volume I: Introduction and Theoretical Development, pp x+370, (2001)
volume II: Interpretation of Seismograms on Regional and Global Scales, pp xii+534, (2002)
Cambridge University Press

Articles 2004

184 Yoshizawa K. & Kennett B.L.N. (2004), Multi-mode surface wave tomography for the Australian region using a 3-stage approach incorporating finite frequency effects, J. Geophys. Res., 109, B02310, doi:10.1029/2002JB002254 [PDF]

Rawlinson N. & Kennett B.L.N. (2004), Rapid estimation of relative and absolute delay times across a network by adaptive stacking, Geophys. J. Int., 157, 332-340. [PDF]

Kennett B.L.N. & Gorbatov, A. (2004), Seismic heterogeneity in the mantle - Strong shear wave signature of slabs, Phys. Earth. Planet. Inter., 146, 88-100. [PDF]

Kennett B.L.N. (2004), Consistency regions in nonlinear inversion, Geophys. J. Int., 157, 583-588. [PDF]

Hong T.-K., Kennett B.L.N. & R.-S. Wu (2004), Effects of the density perturbation in scattering, Geophys. Res. Lett., 31(13), L13602, doi:10.1029/2004GL019933. [PDF]

Miller M.S., Kennett B.L.N. & Lister G.S. (2004), Imaging changes in morphology, geometry and physical properties of the subducting Pacific plate along the Izu-Bonin-Mariana arc, Earth Planet. Sci. Lett., 224, 363-370. [PDF]

Poupinet G. & Kennett B.L.N. (2004), On the observation of high frequency PKiKP and its coda in Australia, Phys. Earth. Planet. Inter., 146, 497-511. [PDF]

Kennett B.L.N., Fishwick S., Reading A.M. & Rawlinson N. (2004) Contrasts in mantle structure beneath Australia: relation to Tasman Lines?, Aust. J. Earth Sci., 51, 563-569. [PDF]

Hong T.-K. & Kennett B.L.N. (2004), Scattering of elastic waves in media with a random distribution of fluid-filled cavities: theory and numerical modeling, Geophys. J. Int., 159, 961-977. [PDF]

Kennett B.L.N., Fishwick S. & Heintz M. (2004) Lithospheric structure in the Australian region - a synthesis of surface wave and body wave studies, Exploration Geophysics, 35, 242-250. [PDF]

Debayle E., Kennett B. & Priestley K. (2005) Global azimuthal seismic anisotropy: the unique plate-motion deformation of Australia, Nature, 433, 509-512. [PDF]

Hong T.-K., Wu R.-S. & Kennett B.L.N. (2005) Stochastic features of scattering, Phys. Earth. Planet. Inter., 148, 131-148. [PDF]

Fishwick S., Kennett B.L.N. & Reading A.M. (2005) Contrasts in lithospheric structure within the Australian Craton, Earth Planet Sci. Lett., 231, 163-176. [PDF]

Tokoyuni G, Takenaka H., Wang Y. & Kennett B.L.N. (2005) Quasi-spherical approach for seismic wave modeling in a 2D slice of a global Earth model with lateral heterogeneity, Geophys. Res. Lett., 32, L09305, doi:10.1029/2004GL022180. [PDF]

Miller M.S., Gorbatov A. & Kennett B.L.N. (2005) Heterogeneity within the subducting Pacific plate beneath the Izu-Bonin-Mariana arc: evidence from tomography using 3D ray-tracing inversion techniques, Earth Planet Sci. Lett., 235, 331-342. [PDF]

Heintz M. & Kennett B.L.N. (2005) Continental scale shear-wave splitting analysis: Investigation of seismic anisotropy underneath the Australian continent, Earth Planet Sci. Lett., 236, 106-119. [PDF]

Yoshizawa K & Kennett B.L.N. (2005) Sensitivity kernels for finite frequency surface waves, Geophys. J. Int., 162, 910-926. doi: 10.1111/j.1365-246X.2005.02679.x. [PDF]

Furumura T & Kennett B.L.N. (2005) Subduction zone guided waves and the heterogeneity structure of the subducted plate, J. Geophys. Res., 110(B10), B10302, doi:10.129/2004JB003486. [PDF]

Kennett B.L.N. & Cummins P.R. (2005) Relationship of the seismic source and subduction zone structure for the 2004 Dec 26 Sumatra-Andaman Earthquake, Earth Planet. Sci. Lett., 239, 1-8. [PDF]

Rawlinson N., Reading A.M. & Kennett B.L.N. (2006) Lithospheric structure of Tasmania from teleseismic tomography: implications for Phanerozoic evolution of Eastern Australia, J. Geophys. Res., 111, B02301, doi:10.129/2005JB003803. [PDF]

Miller M.S., Kennett B.L.N. & Toy V. (2006) Spatial and temporal evolution of the subducting Pacific plate structure along the western Pacific margin, J. Geophys. Res., 111, B02401, doi:10.129/2005JB003705. [PDF]

Miller, M.S., Kennett, B.L.N., A. Gorbatov(2006), Morphology of the distorted subducted Pacific slab beneath the Hokkaido corner, Phys. Earth Planet. Inter., 156, 1-11. [PDF]

Miller, M.S., Kennett, B.L.N. (2006), Evolution of mantle structure beneath the Northwest Pacific: evidence from seismic tomography and paleogeographic reconstructions, Tectonics, 25, TC4002, doi: 10.1029/2005TC001909. [PDF]

Miller M. S., A. Gorbatov, B. L. N. Kennett (2006), Three-dimensional visualization of a near-vertical slab tear beneath the southern Mariana arc, Geochem. Geophys. Geosyst., 7, Q06012, doi:10.1029/2005GC001110 [PDF].

Rawlinson N., Kennett B.L.N. & Heintz M. (2006), Insights into the structure of the upper mantle beneath the Murray Basin from 3-D teleseismic tomography, Aust. J. Earth. Sci., 53, 595-604. [PDF]

Heintz M. & Kennett B.L.N. (2006), The apparently isotropic Australian upper mantle Geophys. Res. Lett., 33, L15319. [PDF]

Kennett B.L.N. (2006a), Nonlinear methods for seismic event location in a global context, Phys. Earth Planet. Inter., 158, 46-54. [PDF]

Kennett B.L.N. (2006b), On seismological reference models and the perceived nature of heterogeneity, Phys. Earth Planet. Inter., 159, 129-139. [PDF]

Kennett B.L.N. (2006c), Developments in passive seismic techniques through the ANSIR National Research Facility, Expl. Geophys., 37, 278-285. [PDF]

Visser, K., Lebedev, S., Trampert, J., Kennett, B.L.N. (2007), Global Love wave overtone measurements, Geophys. Res Lett., 34, L03302, doi:10.1029/2006GL028671.

Reading, A.M., Kennett,B.L.N., Goleby B.R. (2007), Global New constraints on the seismic structure of West Australia: Evidence for terrane stabilization prior to the assembly of an ancient continent?, Geology, 35, 379-382, doi:10.1130/G23341A.1.

Schweitzer, J., Kennett, B.L.N., (2007), Comparison of location procedures: The Kara Sea event of 16 August 1997, Bull. Seism. Soc. Am., 97, 389-400; doi:10.1785/0120040017