Adjoint Tomography for the Middle East

Adjoint Tomography for the Middle East Shear-velocity event kernel for an earthquake in the strait of Hormuz recorded 2005 by several regional stations. Sensitivities are shown on a horizontal cross-section at 5 km depth and a vertical cross-section through the source and a station location down to a depth of 670 km.
<p>
We evaluate 3D models of the Middle East by computing full waveforms for a set of regional earthquakes [Savage et al., 2009]. We measure traveltime shifts between observed broadband data obtained from IRIS and synthetic seismograms for distinct seismic phases within selected time windows using a recently developed, automated measurement algorithm [Maggi et al., 2009]. Based on the measurements for our study region, we selected a best model to feature as the starting seismic model for a fully numerical 3D seismic tomography approach.
</p><p>In order to improve the initial 3D seismic model, the sensitivity to seismic structure of the traveltime measurements for all available, regional network recordings is computed. As this represents a computationally very intensive task, we take advantage of an adjoint method combined with spectral-element simulations [Tromp et al., 2005]. We calculate such sensitivity kernels for all seismic events and regional records and use them in a conjugate-gradient approach to iteratively update the 3D seismic model. This will lead to various improvements of the initial seismic structure in order to better explain regional seismic wave-forms in the Middle East for nuclear monitoring.
</p><p>References
</p><p>Maggi, A., C. Tape, M. Chen, D. Chao and J. Tromp, 2009. An Automated time-window selection algorithm for seismic tomography, Geophys. J. Int., 178, 257–281.
</p><p>Savage, B., D. Peter, B. Covellone, A. Rodgers and J. Tromp, 2009. Progress towards next generation, waveform based three-dimensional models and metrics to improve nuclear explosion monitoring in the Middle East, Proceedings of the 31th Monitoring Research Review of Ground-Based Nuclear Explosion Monitoring Technologies, LLNL-PROC-414451, 9 pages.
</p><p>Tromp, J., C. Tape and Q. Y. Liu, 2005. Seismic tomography, adjoint methods, time reversal and banana-doughnut kernels, Geophys. J. Int., 160, 195–216.
</p><p>Acknowledgements: This research is sponsored by Air Force Research Laboratory and by National Nuclear Security Administration, Contract No. FA8718-08-C-0009.</p>

Comments

No comments yet.

  •  

Welcome

Welcome to the IRIS Image Gallery – a diverse collection of photographs and visuals that encompass the range and breadth of seismology and the seismological community.

Please browse through our albums. These low and medium-resolution images can be freely used for personal and educational/academic purposes, but we request you recognize the image contributor by including in your product or presentation the credit displayed with each image.

More information is available in the Image Use Agreement.

If you have any comments, questions, or suggestions related to the IRIS Image Gallery, you can send them to gallery@iris.edu.

Photo info

  • Title: Adjoint Tomography for the Middle East
  • Description: Adjoint Tomography for the Middle East Shear-velocity event kernel for an earthquake in the strait of Hormuz recorded 2005 by several regional stations. Sensitivities are shown on a horizontal cross-section at 5 km depth and a vertical cross-section through the source and a station location down to a depth of 670 km.
    <p>
    We evaluate 3D models of the Middle East by computing full waveforms for a set of regional earthquakes [Savage et al., 2009]. We measure traveltime shifts between observed broadband data obtained from IRIS and synthetic seismograms for distinct seismic phases within selected time windows using a recently developed, automated measurement algorithm [Maggi et al., 2009]. Based on the measurements for our study region, we selected a best model to feature as the starting seismic model for a fully numerical 3D seismic tomography approach.
    </p><p>In order to improve the initial 3D seismic model, the sensitivity to seismic structure of the traveltime measurements for all available, regional network recordings is computed. As this represents a computationally very intensive task, we take advantage of an adjoint method combined with spectral-element simulations [Tromp et al., 2005]. We calculate such sensitivity kernels for all seismic events and regional records and use them in a conjugate-gradient approach to iteratively update the 3D seismic model. This will lead to various improvements of the initial seismic structure in order to better explain regional seismic wave-forms in the Middle East for nuclear monitoring.
    </p><p>References
    </p><p>Maggi, A., C. Tape, M. Chen, D. Chao and J. Tromp, 2009. An Automated time-window selection algorithm for seismic tomography, Geophys. J. Int., 178, 257–281.
    </p><p>Savage, B., D. Peter, B. Covellone, A. Rodgers and J. Tromp, 2009. Progress towards next generation, waveform based three-dimensional models and metrics to improve nuclear explosion monitoring in the Middle East, Proceedings of the 31th Monitoring Research Review of Ground-Based Nuclear Explosion Monitoring Technologies, LLNL-PROC-414451, 9 pages.
    </p><p>Tromp, J., C. Tape and Q. Y. Liu, 2005. Seismic tomography, adjoint methods, time reversal and banana-doughnut kernels, Geophys. J. Int., 160, 195–216.
    </p><p>Acknowledgements: This research is sponsored by Air Force Research Laboratory and by National Nuclear Security Administration, Contract No. FA8718-08-C-0009.</p>
  • File name: beta_kernel-event.jpg
  • Owner: Rick Callender
  • Dimensions: 1243 x 938 px

Popular tags