دورية أكاديمية
Full seismic waveform tomography for upper-mantle structure in the Australasian region using adjoint methods
| العنوان: | Full seismic waveform tomography for upper-mantle structure in the Australasian region using adjoint methods |
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| المؤلفون: | Fichtner, Andreas, Kennett, Brian, Igel, Heiner, Bunge, Hans-Peter |
| المصدر: | Geophysical Journal International |
| بيانات النشر: | Blackwell Publishing Ltd |
| المجموعة: | Australian National University: ANU Digital Collections |
| مصطلحات موضوعية: | Keywords: adjoint method, algorithm, amplitude, body wave, computer simulation, data inversion, heterogeneity, mantle structure, nonlinearity, numerical model, optimization, S-wave, seismic tomography, source parameters, upper mantle, wave field, wave propagation, Australia, Computational seismology, Inverse theory, Numerical solutions, Surface waves and free oscillations |
| الوصف: | We present a full seismic waveform tomography for upper-mantle structure in the Australasian region. Our method is based on spectral-element simulations of seismic wave propagation in 3-D heterogeneous earth models. The accurate solution of the forward problem ensures that waveform misfits are solely due to as yet undiscovered Earth structure and imprecise source descriptions, thus leading to more realistic tomographic images and source parameter estimates. To reduce the computational costs, we implement a long-wavelength equivalent crustal model.We quantify differences between the observed and the synthetic waveforms using time-frequency (TF) misfits. Their principal advantages are the separation of phase and amplitude misfits, the exploitation of complete waveform information and a quasi-linear relation to 3-D Earth structure. Fréchet kernels for the TF misfits are computed via the adjoint method. We propose a simple data compression scheme and an accuracy-adaptive time integration of the wavefields that allows us to reduce the storage requirements of the adjoint method by almost two orders of magnitude.To minimize the waveform phase misfit, we implement a pre-conditioned conjugate gradient algorithm. Amplitude information is incorporated indirectly by a restricted line search. This ensures that the cumulative envelope misfit does not increase during the inversion. An efficient pre-conditioner is found empirically through numerical experiments. It prevents the concentration of structural heterogeneity near the sources and receivers.We apply our waveform tomographic method to ≈1000 high-quality vertical-component seismograms, recorded in the Australasian region between 1993 and 2008. The waveforms comprise fundamental- and higher-mode surface and long-period S body waves in the period range from 50 to 200 s. To improve the convergence of the algorithm, we implement a 3-D initial model that contains the long-wavelength features of the Australasian region. Resolution tests indicate that our algorithm converges ... |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | unknown |
| تدمد: | 0956-540X |
| العلاقة: | http://hdl.handle.net/1885/38572Test; https://openresearch-repository.anu.edu.au/bitstream/1885/38572/5/gji-179-1703.pdf.jpgTest; https://openresearch-repository.anu.edu.au/bitstream/1885/38572/7/01_Fichtner_Full_seismic_waveform_2009.pdf.jpgTest |
| DOI: | 10.1111/j.1365-246X.2009.04368.x |
| الإتاحة: | https://doi.org/10.1111/j.1365-246X.2009.04368.xTest http://hdl.handle.net/1885/38572Test https://openresearch-repository.anu.edu.au/bitstream/1885/38572/5/gji-179-1703.pdf.jpgTest https://openresearch-repository.anu.edu.au/bitstream/1885/38572/7/01_Fichtner_Full_seismic_waveform_2009.pdf.jpgTest |
| رقم الانضمام: | edsbas.6AD5DB84 |
| قاعدة البيانات: | BASE |
| تدمد: | 0956540X |
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| DOI: | 10.1111/j.1365-246X.2009.04368.x |