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Volumn 278, Issue 5336, 1997, Pages 254-257

Depth extent of the Lau back-arc spreading center and its relation to subduction processes

Author keywords

[No Author keywords available]

Indexed keywords

BACKARC BASIN; BACKARC BASINS; MANGLE CONVECTION; MANTLE PROCESSES; MANTLE WEDGE; SEA FLOOR SPREADING; SEAFLOOR SPREADING; SEISMIC TOMOGRAPHY; SUBDUCTION;

EID: 0030881678     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.278.5336.254     Document Type: Article
Times cited : (193)

References (47)
  • 1
    • 0002337261 scopus 로고
    • M. Talwani and W. C. Pitman III, Eds. American Geophysical Union, Washington, DC
    • S. Uyeda, in Island Arcs, Deep Sea Trenches and Back-Arc Basins, M. Talwani and W. C. Pitman III, Eds. (American Geophysical Union, Washington, DC, 1977), pp. 1-14; M. N. Toksoz and P. Bird, in Island Arcs, Deep Sea Trenches and Back-Arc Basins, M. Talwani and W. C. Pitman III, Eds. (American Geophysical Union, Washington, DC, 1977), pp. 379-393; N. H. Sleep and M. N. Toksoz, Nature 33, 548 (1971).
    • (1977) Island Arcs, Deep Sea Trenches and Back-Arc Basins , pp. 1-14
    • Uyeda, S.1
  • 2
    • 0001641964 scopus 로고
    • M. Talwani and W. C. Pitman III, Eds. American Geophysical Union, Washington, DC
    • S. Uyeda, in Island Arcs, Deep Sea Trenches and Back-Arc Basins, M. Talwani and W. C. Pitman III, Eds. (American Geophysical Union, Washington, DC, 1977), pp. 1-14; M. N. Toksoz and P. Bird, in Island Arcs, Deep Sea Trenches and Back-Arc Basins, M. Talwani and W. C. Pitman III, Eds. (American Geophysical Union, Washington, DC, 1977), pp. 379-393; N. H. Sleep and M. N. Toksoz, Nature 33, 548 (1971).
    • (1977) Island Arcs, Deep Sea Trenches and Back-Arc Basins , pp. 379-393
    • Toksoz, M.N.1    Bird, P.2
  • 3
    • 0002830162 scopus 로고
    • S. Uyeda, in Island Arcs, Deep Sea Trenches and Back-Arc Basins, M. Talwani and W. C. Pitman III, Eds. (American Geophysical Union, Washington, DC, 1977), pp. 1-14; M. N. Toksoz and P. Bird, in Island Arcs, Deep Sea Trenches and Back-Arc Basins, M. Talwani and W. C. Pitman III, Eds. (American Geophysical Union, Washington, DC, 1977), pp. 379-393; N. H. Sleep and M. N. Toksoz, Nature 33, 548 (1971).
    • (1971) Nature , vol.33 , pp. 548
    • Sleep, N.H.1    Toksoz, M.N.2
  • 4
    • 0000252498 scopus 로고
    • J. Morgan, D. Blackman, J. Sinton, Eds. American Geophysical Union, Washington, DC
    • D. W. Forsyth, in Mantle Flow and Melt Generation at Mid-Ocean Ridges, J. Morgan, D. Blackman, J. Sinton, Eds. (American Geophysical Union, Washington, DC, 1993), pp. 1-65; D. L. Turcotte and J. P. Morgan, in ibid., pp. 155-182.
    • (1993) Mantle Flow and Melt Generation at Mid-Ocean Ridges , pp. 1-65
    • Forsyth, D.W.1
  • 7
    • 0019365445 scopus 로고
    • L. N. Huppert and C. Frohlich, J. Geophys. Res. 86, 3771 (1981); G. Bock, ibid. 92, 13863 (1987); K. M. Fischer, K. C. Creager, J. H. Jordan, ibid. 96, 14403 (1991).
    • (1981) J. Geophys. Res. , vol.86 , pp. 3771
    • Huppert, L.N.1    Frohlich, C.2
  • 8
    • 0019365445 scopus 로고
    • L. N. Huppert and C. Frohlich, J. Geophys. Res. 86, 3771 (1981); G. Bock, ibid. 92, 13863 (1987); K. M. Fischer, K. C. Creager, J. H. Jordan, ibid. 96, 14403 (1991).
    • (1987) J. Geophys. Res. , vol.92 , pp. 13863
    • Bock, G.1
  • 10
    • 0025209564 scopus 로고    scopus 로고
    • H. Zhou, Phys. Earth Planet. Inter. 61, 199 (1990); J. Geophys. Res. 101, 27791 (1996); R. van der Hilst, Nature 374, 154 (1995).
    • (1990) Phys. Earth Planet. Inter. , vol.61 , pp. 199
    • Zhou, H.1
  • 11
    • 0025209564 scopus 로고    scopus 로고
    • H. Zhou, Phys. Earth Planet. Inter. 61, 199 (1990); J. Geophys. Res. 101, 27791 (1996); R. van der Hilst, Nature 374, 154 (1995).
    • (1996) J. Geophys. Res. , vol.101 , pp. 27791
  • 12
    • 0028830376 scopus 로고
    • H. Zhou, Phys. Earth Planet. Inter. 61, 199 (1990); J. Geophys. Res. 101, 27791 (1996); R. van der Hilst, Nature 374, 154 (1995).
    • (1995) Nature , vol.374 , pp. 154
    • Van Der Hilst, R.1
  • 16
    • 0027044743 scopus 로고
    • D. Zhao, A. Hasegawa, S. Horiuchi, ibid.. 97, 19909 (1992); D. Zhao, A. Hasegawa, H. Kanamori, ibid. 99, 22313 (1994). A 3D net of nodes was set up in the Tonga-Fiji region with a horizontal grid spacing of 50 km and a vertical spacing of 25 to 50 km. Hypocentral locations of earthquakes and velocities at the grid nodes were taken as unknown parameters. The velocity at any point was calculated by linearly interpolating the velocities at the eight grid nodes surrounding that point. An efficient 3D ray tracing technique was used to calculate ray paths and travel times. A conjugate gradient algorithm [C. Paige and M. Saunders, ACM Trans. Math. Software 8, 43 (1982)] was used to solve the large sparse system of observational equations by regularizing the solution in a damped least-squares fashion [K. Aki and W. Lee, J. Geophys. Res. 81, 4381 (1976)]. The nonlinear tomographic problem was solved by iteratively conducting linear inversions. Hypocenters were relocated in the inversion process. For the local data from the 926 events (Fig. 1), raw arrival times were used in the inversion. For the teleseismic data with epicentral distances greater than 30°, we used the relative travel time residuals by removing the average of the travel time residuals for each station, to remove the effect of the structures outside the study area.
    • (1992) J. Geophys. Res. , vol.97 , pp. 19909
    • Zhao, D.1    Hasegawa, A.2    Horiuchi, S.3
  • 17
    • 0028555604 scopus 로고
    • D. Zhao, A. Hasegawa, S. Horiuchi, ibid.. 97, 19909 (1992); D. Zhao, A. Hasegawa, H. Kanamori, ibid. 99, 22313 (1994). A 3D net of nodes was set up in the Tonga-Fiji region with a horizontal grid spacing of 50 km and a vertical spacing of 25 to 50 km. Hypocentral locations of earthquakes and velocities at the grid nodes were taken as unknown parameters. The velocity at any point was calculated by linearly interpolating the velocities at the eight grid nodes surrounding that point. An efficient 3D ray tracing technique was used to calculate ray paths and travel times. A conjugate gradient algorithm [C. Paige and M. Saunders, ACM Trans. Math. Software 8, 43 (1982)] was used to solve the large sparse system of observational equations by regularizing the solution in a damped least-squares fashion [K. Aki and W. Lee, J. Geophys. Res. 81, 4381 (1976)]. The nonlinear tomographic problem was solved by iteratively conducting linear inversions. Hypocenters were relocated in the inversion process. For the local data from the 926 events (Fig. 1), raw arrival times were used in the inversion. For the teleseismic data with epicentral distances greater than 30°, we used the relative travel time residuals by removing the average of the travel time residuals for each station, to remove the effect of the structures outside the study area.
    • (1994) J. Geophys. Res. , vol.99 , pp. 22313
    • Zhao, D.1    Hasegawa, A.2    Kanamori, H.3
  • 18
    • 0039943513 scopus 로고
    • D. Zhao, A. Hasegawa, S. Horiuchi, ibid.. 97, 19909 (1992); D. Zhao, A. Hasegawa, H. Kanamori, ibid. 99, 22313 (1994). A 3D net of nodes was set up in the Tonga-Fiji region with a horizontal grid spacing of 50 km and a vertical spacing of 25 to 50 km. Hypocentral locations of earthquakes and velocities at the grid nodes were taken as unknown parameters. The velocity at any point was calculated by linearly interpolating the velocities at the eight grid nodes surrounding that point. An efficient 3D ray tracing technique was used to calculate ray paths and travel times. A conjugate gradient algorithm [C. Paige and M. Saunders, ACM Trans. Math. Software 8, 43 (1982)] was used to solve the large sparse system of observational equations by regularizing the solution in a damped least-squares fashion [K. Aki and W. Lee, J. Geophys. Res. 81, 4381 (1976)]. The nonlinear tomographic problem was solved by iteratively conducting linear inversions. Hypocenters were relocated in the inversion process. For the local data from the 926 events (Fig. 1), raw arrival times were used in the inversion. For the teleseismic data with epicentral distances greater than 30°, we used the relative travel time residuals by removing the average of the travel time residuals for each station, to remove the effect of the structures outside the study area.
    • (1982) ACM Trans. Math. Software , vol.8 , pp. 43
    • Paige, C.1    Saunders, M.2
  • 19
    • 0016986090 scopus 로고
    • D. Zhao, A. Hasegawa, S. Horiuchi, ibid.. 97, 19909 (1992); D. Zhao, A. Hasegawa, H. Kanamori, ibid. 99, 22313 (1994). A 3D net of nodes was set up in the Tonga-Fiji region with a horizontal grid spacing of 50 km and a vertical spacing of 25 to 50 km. Hypocentral locations of earthquakes and velocities at the grid nodes were taken as unknown parameters. The velocity at any point was calculated by linearly interpolating the velocities at the eight grid nodes surrounding that point. An efficient 3D ray tracing technique was used to calculate ray paths and travel times. A conjugate gradient algorithm [C. Paige and M. Saunders, ACM Trans. Math. Software 8, 43 (1982)] was used to solve the large sparse system of observational equations by regularizing the solution in a damped least-squares fashion [K. Aki and W. Lee, J. Geophys. Res. 81, 4381 (1976)]. The nonlinear tomographic problem was solved by iteratively conducting linear inversions. Hypocenters were relocated in the inversion process. For the local data from the 926 events (Fig. 1), raw arrival times were used in the inversion. For the teleseismic data with epicentral distances greater than 30°, we used the relative travel time residuals by removing the average of the travel time residuals for each station, to remove the effect of the structures outside the study area.
    • (1976) J. Geophys. Res. , vol.81 , pp. 4381
    • Aki, K.1    Lee, W.2
  • 20
    • 85041256609 scopus 로고    scopus 로고
    • D. Zhao et al., Eos (Fall Suppl.) 77, 498 (1996). The starting 1D model for the inversion was the IASP91 Earth model (25), but the crustal thickness has lateral variations according to a seismic refraction survey along the line of OBS stations (26) and the inversion of land station wave forms (75). The crustal thickness varies from 5 to 24 km, with the thickest crust beneath the Lau Ridge, Tonga arc, and Fiji Islands. Numerous previous studies (4, 5) have demonstrated the existence of the Tonga slab, which is at least 100 km thick with a P wave velocity of up to 7% faster. The slab substantially perturbs ray trajectories, such that the ray path perturbation can be over 100 km from that in the 1D Earth model (4, 9). Our primary concern in this study is the precise structure below the Lau Basin and in the mantle wedge. For this purpose, it was necessary to use a starting model incorporating the a priori slab information (8, 9) because we hoped to resolve the anomalies in the Lau Basin with a resolution of 50 to 70 km. We introduced the Tonga slab into the model using the slab geometry determined by Billington (27). The introduction of the slab into the model reduced the nonlinearity of the problem because seismic rays are traced realistically from the beginning of the inversion (8, 9). We conducted a number of inversions by changing the initial slab thickness from 50 to 150 km and the initial slab velocity from 1 to 9% faster than the normal mantle. We also conducted inversions without the slab in the starting model. All of the inversions imaged the very slow velocity anomalies beneath the Lau spreading center to about 100-km depth and the moderately slow anomalies to about 400-km depth, but there are 1 to 2.5% changes in the amplitudes of the anomalies and up to 10% changes in the final travel time residuals. The inversion with the starting model that included a 100-km-thick slab and that was 6% faster than the normal mantle resulted in the best fit of model to data. The results of this inversion are shown in Figs. 2 and 3.
    • (1996) Eos (Fall Suppl.) , vol.77 , pp. 498
    • Zhao, D.1
  • 21
    • 1842352219 scopus 로고    scopus 로고
    • note
    • To make a checkerboard in the resolution tests, we assigned positive and negative velocity anomalies with magnitudes of 5% to the 3D grid nodes. Synthetic data were calculated for the checkerboard model. Then we added random errors to the synthetic data and inverted them with the same algorithm that we used for the observed data. The inverted image of the checkerboard suggests where the resolution is good and where it is poor. The checkerboard resolution tests and other synthetic tests we conducted showed that both the high-velocity Tonga slab and the low-velocity back arc and mantle wedge were reliably resolved and that there was no trade-off between them.
  • 22
    • 0024484257 scopus 로고
    • Y. Tatsumi, J. Geophys. Res. 94, 4697 (1989); J. H. Davies and D. J. Stevenson, ibid. 97, 2037 (1992).
    • (1989) J. Geophys. Res. , vol.94 , pp. 4697
    • Tatsumi, Y.1
  • 24
    • 0026478959 scopus 로고
    • Y. Zhang and T. Tanimoto, Nature 355, 45 (1992); T. Tanimoto and D. J. Stevenson, J. Geophys. Res. 99, 4549 (1994).
    • (1992) Nature , vol.355 , pp. 45
    • Zhang, Y.1    Tanimoto, T.2
  • 27
    • 1842357171 scopus 로고    scopus 로고
    • in press
    • Y. Xu and D. Wiens, ibid., in press. To invert regional wave forms we used a nonlinear inversion method that adopts a reflectivity formalism (28) to compute the partial derivatives. This method allows the entire regional distance (400-to 1500-km range) wave form to be inverted from P wave arrival to surface waves at frequencies between 0.01 and 0.055 Hz. Broadband seismograms from earthquakes of 10 to 240 km deep that propagate almost entirely within one of the tectonic regions of the southwest Pacific were used in the wave form inversion. Parameter variances and resolution tests suggest that the results are well constrained to depths of about 200 km. The S wave velocities from the wave form inversion and the P wave velocities from the tomography would not necessarily show the same structure. The larger total heterogeneity from the wave form inversion may result from a greater effect of partial melt beneath the Lau back arc on S wave velocity than on P wave velocity (9, 29).
    • J. Geophys. Res.
    • Xu, Y.1    Wiens, D.2
  • 29
    • 0028574902 scopus 로고
    • G. Nolet and A. Zielhuis, J. Geophys. Res. 99, 15813 (1994); G. Nolet, in Processes of Deep Earth and Planetary Volatiles, K. Farley, Ed. (American Institute of Physics, New York, 1995), pp. 22-32.
    • (1994) J. Geophys. Res. , vol.99 , pp. 15813
    • Nolet, G.1    Zielhuis, A.2
  • 30
    • 0006939117 scopus 로고
    • K. Farley, Ed. American Institute of Physics, New York
    • G. Nolet and A. Zielhuis, J. Geophys. Res. 99, 15813 (1994); G. Nolet, in Processes of Deep Earth and Planetary Volatiles, K. Farley, Ed. (American Institute of Physics, New York, 1995), pp. 22-32.
    • (1995) Processes of Deep Earth and Planetary Volatiles , pp. 22-32
    • Nolet, G.1
  • 31
    • 0027063496 scopus 로고
    • A. B. Thompson, Nature 358, 295 (1992); H. Staudigel and S. D. King, Earth Planet Sci. Lett. 109, 517 (1992).
    • (1992) Nature , vol.358 , pp. 295
    • Thompson, A.B.1
  • 37
    • 0030437840 scopus 로고    scopus 로고
    • L. M. Parson and I. C. Wright, Tectonophysics 263, 1 (1996); B. Taylor, K. Zellmer, F. Martinez, A. Goodliffe, Earth Planet. Sci. Lett. 144, 35 (1996).
    • (1996) Tectonophysics , vol.263 , pp. 1
    • Parson, L.M.1    Wright, I.C.2
  • 39
    • 0003034347 scopus 로고
    • J. L. Smellie, Ed. Geological Society, London
    • J. A. Pearce et al., in Volcanism Associated with Extension at Consuming Plate Margins, J. L. Smellie, Ed. (Geological Society, London, 1992), pp. 53-75; J. W. Hawkins, in Active Margins and Marginal Basins of the Western Pacific, B. Taylor and J. Natland, Eds. (American Geophysical Union, Washington, DC, 1995), pp. 125-173.
    • (1992) Volcanism Associated with Extension at Consuming Plate Margins , pp. 53-75
    • Pearce, J.A.1
  • 40
    • 84983241985 scopus 로고
    • B. Taylor and J. Natland, Eds. American Geophysical Union, Washington, DC
    • J. A. Pearce et al., in Volcanism Associated with Extension at Consuming Plate Margins, J. L. Smellie, Ed. (Geological Society, London, 1992), pp. 53-75; J. W. Hawkins, in Active Margins and Marginal Basins of the Western Pacific, B. Taylor and J. Natland, Eds. (American Geophysical Union, Washington, DC, 1995), pp. 125-173.
    • (1995) Active Margins and Marginal Basins of the Western Pacific , pp. 125-173
    • Hawkins, J.W.1
  • 43
    • 1842395758 scopus 로고
    • thesis, Cornell University, Ithaca, NY
    • S. Billington, thesis, Cornell University, Ithaca, NY, (1980).
    • (1980)
    • Billington, S.1
  • 45
    • 0028255121 scopus 로고
    • B. L. N. Kennett, Seismic Wave Propagation in Stratified Media (Cambridge Univ. Press, Cambridge, 1983); G. E. Randall, Geophys. J. Int. 118, 245 (1994).
    • (1994) Geophys. J. Int. , vol.118 , pp. 245
    • Randall, G.E.1
  • 47
    • 1842310863 scopus 로고    scopus 로고
    • note
    • We thank M. Bevis, W. Crawford, K. Draunidalo, S. Escher, T. Fatai, H. Gilbert, S. Helu, K. Koper, M. McDonald, J. McGuire, B. Park-Li, G. Prasad, E. Roth, A. Sauter, P. Shore, and L. Vuetibau for their assistance during the seismic experiment and at the data-processing stage and G. Abers and an anonymous referee for thoughtful reviews, which improved the manuscript. Broadband seismographs were obtained from the PASSCAL program of the Incorporated Research Institutions in Seismology (IRIS). Supported by the NSF under grants EAR-9219675, OCE-9314446, and EAR-9614502. This paper is Southern California Earthquake Center publication 386.


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