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New Developments in Ambient Noise Imaging

New Developments in Ambient Noise Imaging. Victor C. Tsai Seismological Laboratory, California Institute of Technology June 11 th , 2014 IRIS Workshop Sunriver, Oregon. Outline. Previous studies… Ambient noise surface waves Temporal variability in velocity structure

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New Developments in Ambient Noise Imaging

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  1. New Developments in Ambient Noise Imaging Victor C. Tsai Seismological Laboratory, California Institute of Technology June 11th, 2014 IRIS Workshop Sunriver, Oregon

  2. Outline Previous studies… • Ambient noise surface waves • Temporal variability in velocity structure New work (in the last ~2 years): • Body wave imaging • Monitoring of time variations • Improvement in theory/understanding • Multi-component correlations • Amplitudes • Imaging physical processes through ‘noise’

  3. Previous Noise Correlation Applications • Aki, BERI (1957): • Noise correlation matches surface wave Green’s function • Campillo & Paul, Science (2003): • Coda correlation similar, waveforms reasonable • Shapiro et al., Science (2005) • Tomography reasonable

  4. Time-dependent velocities • Sens-Schönfelder & Wegler, GRL 2006: • Hydrology at volcano • Brenguier et al., Science (2008): • Earthquake • Similar study shows variability with volcano deformation Parkfield earthquake time 

  5. Outline Previous studies… • Ambient noise surface waves • Temporal variability in velocity structure New work (in the last ~2 years): • Body wave imaging • Monitoring of time variations • Improvement in theory/understanding • Multi-component correlations • Amplitudes • Imaging physical processes through ‘noise’

  6. Body Wave Imaging • Most noise at surface  surface waves dominate • Does ‘noise’-based body-wave imaging work? • Simple regions: flat & cratonic • SmS: Zhan et al. 2010 • P410P, P660P: Poli et al. 2012

  7. Body Wave Imaging • Core phases (from eq. coda): ScS, PKIKP2 • Global correlations • Antipodal phases, targeted time window (no stacking) Array interferometry using all of USArray Lin et al. 2013

  8. Body Wave Imaging • Core phases (from eq. coda): ScS, PKIKP2 • Global correlations • Antipodal phases, targeted time window (no stacking) Nishida 2013 Boue et al. 2013 Lin et al. 2013

  9. Body Wave Imaging • Core phases (from eq. coda): ScS, PKIKP2 • Global correlations • Antipodal phases, targeted time window (no stacking) Nishida 2013 Boue et al. 2013 Lin & Tsai 2013 Lin et al. 2013

  10. Monitoring of Time Variations • Short timescale variability • Shallow & deep, different timescales for Tohoku • Induced seismicity, injection rate Hadziioannou et al. 2011 3 weeks

  11. Monitoring of Time Variations • Short timescale variability • Shallow & deep, different timescales for Tohoku • Induced seismicity, injection rate Minato et al. 2012

  12. Monitoring of Time Variations • Short timescale variability • Shallow & deep, different timescales for Tohoku • Induced seismicity, injection rate Lai et al., SSA 2014

  13. Monitoring of Time Variations • But one needs to be careful in interpretation… which theory is getting better at characterizing Obermann et al. 2013 Sensitivity kernel in the diffusion regime

  14. Monitoring of Time Variations • But one needs to be careful in interpretation… which theory is getting better at characterizing Apparent velocity change from frequency changes Zhan et al. 2013

  15. Multi-Component Correlations • Can R-Z corr. be useful beyond added travel time? • R-Z SPAC (Haney et al. 2012), OBS R-Z (Zha et al. 2013) • H/V amplitude ratios of NCFs: Lin et al. 2014 Phase velocity At 30s: H/V

  16. Amplitudes • Better theory for correlations • High density arrays Effect of non-const. velocity structure Menon et al. 2014

  17. Amplitudes Amplification 2Hz • Better theory for correlations • High density arrays Phase Velocity 3.3 Hz from Daniel Bowden (in prep.)

  18. Imaging Physical Processes Allstadt 2013 • Landslides • Debris Flows • Rivers • Sediment transport • Turbulent stress • Hurricanes • Sea Ice 100s 200s

  19. Imaging Physical Processes Allstadt 2013 • Landslides • Debris Flows • Rivers • Sediment transport • Turbulent stress • Hurricanes • Sea Ice 100s 200s Gimbert, Tsai, Lamb, submitted 2014

  20. Imaging Physical Processes Sufri et al., EPSL in press • Landslides • Debris Flows • Rivers • Sediment transport • Turbulent stress • Hurricanes • Sea Ice

  21. Imaging Physical Processes Sufri et al., EPSL in press • Landslides • Debris Flows • Rivers • Sediment transport • Turbulent stress • Hurricanes • Sea Ice Tsai & McNamara 2011 0.6-2.0s Spectral Power (dB)

  22. Lots of new and unexpected results in ambient noise imaging!

  23. Previous Noise Correlation Applications Aki, BERI (1957): Noise correlation matches surface wave Green’s function Campillo & Paul, Science (2003): Coda correlation similar Shapiro et al., Science (2005) tomography reasonable waveforms reasonable

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