3D seismic imaging of the earth’s mantle

1. 3D seismic imaging of the earth’s mantle Barbara Romanowicz Department of Earth and Planetary Science U.C. Berkeley

3. Surface waves

4. Loma Prieta (CA) 1989 M 7 earthquake observed at KEV, Finland Surface waves Surface waves SS S P P

6. Global Transverse Component Stacks Shearer, 1991

8. After Park et al, 2005

9. Sumatra 12/26/04 M9.3 (0.8 to 2.2 mHz) CAN 1S5 3S2 1S4 UNM 0S12 0S9 0S8 0S13 0S7 0S10 0S0 0S11 0S5 0S5 1S3 /3S1 0S6 mHz x10 200 hours starting 10 hours before origin time

11. PRELIMINARY REFERENCE EARTH MODEL (PREM) Solid Inner Core Liquid Outer Core Lower Mantle Upper mantle 0 1210 3480 5700 6371 Radius [km] Dziewonski and Anderson, 1981

16. (Albarède and van der Hilst, 1999

17. P-wave travel time tomography Van der Hilst et al., 1998

19. S wave tomography SH SV

20. Seismic Anisotropy x = (Vsh/Vsv)2 Montagner, 2002

21. Motivation for seismic Q tomography: Faul and Jackson, 2005

22. 3D Shear Velocity Models

23. “SH models” “SV models” Gung et al., 2003

24. S velocity Model: SAW24B16

25. AB CD Hawaii Q-1 “Pacific Superplume”

26. MN ST Q-1 Elastic SAW24B16 African “superplume”

27. ISOTROPIC VELOCITY RADIAL ANISOTROPY = (VSH/VSV)2 Panning and Romanowicz, 2004

28. African Superplume dlnVs ~ -3- -12% Wang and Wen, 2005 Ni and Wen, 2005

29. Vs Vf r Depth ~ 2800 km Ishii and Tromp, 2000

30. Garnero, 1998

31. Courtillot et al., 2003

32. The Earth’s inner core

34. Data Model Anomalous splitting of core sensitive modes

35. Mantle mode Core mode

36. Hemispherical dependence of anisotropy (Tanaka and Hamaguchi, 1995)

37. Garcia and Souriau, 2002

38. Innermost Inner Core ? Ishii and Dziewonski, 2003

39. Differential rotation of the Inner Core

40. Fig. 1. Ray paths of PKP waves and example of waveform doublet used to detect temporal change of travel times through the inner core J. Zhang et al., Science 309, 1357 -1360 (2005) Published by AAAS

41. Fig. 1. Ray paths of PKP waves and example of waveform doublet used to detect temporal change of travel times through the inner core J. Zhang et al., Science 309, 1357 -1360 (2005) Published by AAAS

42. Fig. 4. Difference of BC - DF times, d(BC - DF), at station COL as a function of the time separation between the two events of the doublet J. Zhang et al., Science 309, 1357 -1360 (2005) Published by AAAS

43. STRONG MANTLE HETEROGENEITY? Map: enhanced tomographic map at The core-mantle boundary Bréger et al., EPSL, 2000

44. Current Challenges • Improving resolution of 3D structure: • Wave propagation in strongly heterogeneous 3D media/waveform inversion • Address uneven sampling (oceans) • Fine scale structure of major discontinuities • Attenuation tomography • 3D density structure • Combining information from seismology, mineral physics, geochemistry and geodynamics

45. Cartoon from Cazenave, 2002

46. Garnero, Ann. Rev. 2000 “Scenario for CMB”

47. Cartoon from Hellfrich and Wood, 2001

48. “SH models” “SV models”

49. Fukao et al., 2001

50. Transverse isotropy dln x x = Vsh/Vsv 175 km 300 km