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S-wave Velocity Structure and Radial Anisotropy of Saudi Arabia from Surface Wave Tomography

표면파 토모그래피를 이용한 사우디아라비아의 S파 속도구조 및 이방성 연구

  • Kim, Rinhui (Division of Geology and Geophysics, Kangwon National University) ;
  • Chang, Sung-Joon (Division of Geology and Geophysics, Kangwon National University) ;
  • Mai, Martin (King Abdullah University of Science and Technology (KAUST)) ;
  • Zahran, Hani (Saudi Geological Survey (SGS))
  • 김린희 (강원대학교 지질.지구물리학부) ;
  • 장성준 (강원대학교 지질.지구물리학부) ;
  • ;
  • Received : 2019.01.11
  • Accepted : 2019.02.27
  • Published : 2019.02.28

Abstract

We perform a 3D tomographic inversion using surface wave dispersion curves to obtain S-velocity model and radial anisotropy beneath Saudi Arabia. The Arabian Peninsula is geologically and topographically divided into a shield and a platform. We used event data with magnitudes larger than 5.5 and epicentral distances shorter than $40^{\circ}$ during 2008 ~ 2014 from the Saudi Geological Survey. We obtained dispersion curves by using the multiple filtering technique after preprocessing the event data. We constructed SH- and SV-velocity models and consequently radial anisotropy model at 10 ~ 60 km depths by inverting Love and Rayleigh group velocity dispersion curves with period ranges of 5 ~ 140 s, respectively. We observe high-velocity anomalies beneath the Arabian shield at 10 ~ 30 km depths and low-velocity anomalies beneath the Arabian platform at 10 km depth in the SV-velocity model. This discrepancy may be caused by the difference between the Arabian shield and the Arabian platform, that is, the Arabian shield was formed in Proterozoic thereby old and cold, while the Arabian platform is covered by predominant Paleozoic, Mesozoic, and Cenozoic sedimentary layers. Also we obtained radial anisotropy by estimating the differences between SH- and SV-velocity models. Positive anisotropy is observed, which may be generated by lateral tension due to the slab pull of subducting slabs along the Zagros belt.

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Fig. 2. Ray paths between epicenters and stations for (a) Rayleigh waves and (b) Love waves. Red circles and blue triangles indicate the locations of epicenters and stations, respectively.

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Fig. 3. Group velocity dispersion curves for (a) Rayleigh waves and (b) Love waves with a period range from 5 to 140 s.

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Fig. 4. The depth slices of SV-wave velocity perturbations from checkerboard tests. The input checkerboard models consist of 400 km × 400 km squared anomalies with amplitudes of ± 300 m/s as shown in (a). The other panels show inversion results at (b) 10, (c) 20, (d) 30, (e) 40, (f) 50 and (g) 60 km. Regions not covered by data sets are indicated in gray.

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Fig. 5. The depth slices of SH-wave velocity perturbations from checkerboard tests. The input checkerboard models consist of 400 km × 400 km squared anomalies with amplitudes of ± 300 m/s as shown in (a). The other panels show inversion results at (b) 10, (c) 20, (d) 30, (e) 40, (f) 50 and (g) 60 km. Regions not covered by data sets are indicated in gray.

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Fig. 6. The depth slices of SV-wave velocity model at (a) 10, (b) 20, (c) 30, (d) 40, (e) 50 and (f) 60 km. Regions not covered by data sets are indicated in gray.

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Fig. 7. The depth slices of SH-wave velocity model at (a) 10, (b)20, (c) 30, (d) 40, (e) 50 and (f) 60 km. Regions not covered by data sets are indicated in gray.

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Fig. 8. Radial anisotropy at (a) 10, (b) 20, (c) 30, (d) 40, (e) 50 and (f) 60 km. Most of the Arabian Peninsula is dominated by positive anisotropy. Regions not covered by data sets are in dicatedin gray.

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Fig. 1. (a) Map of the study area. The red lines indicate plate boundaries and the dashed line represents the boundary between the Arabian shield and the Arabian platform. The black arrows indicate the direction of absolute plate motions (ArRajehi et al., 2010). Stations, volcanoes and volcanic field are indicated by blue squares, red triangles and orange areas, respectively. (b) Distribution of events. The blue triangle is the center point of our model and red circles indicate events.

Acknowledgement

Supported by : 기상청

References

  1. ArRajehi, A., McClusky, S., Reilinger, R., Daoud, M., Alchalbi, A., Ergintav, S., Gomez, F., Sholan, J., Bou-Rabee, F., Ogubazghi, G., Haileab, B., Fisseha, S., Asfaw, L., Mahmoud, S., Rayan, A., Bendik, R., and Kogan, L., 2010, Geodetic constraints on present-day motion of the Arabian plate: Implications for Red Sea and Gulf of Aden rifting, Tectonics, 29, TC3011, doi:10.1029/2009TC002482. https://doi.org/10.1029/2009TC002482
  2. Bath, M., 1974, Spectral Analysis in Geophysics, Elsevier, 580.
  3. Baumgardner, J. R., and Frederickson, P. O., 1985, Icosahedral Discretization of the Two-Sphere, SIAM J. Numer. Anal., 22(6), 1107-1115. https://doi.org/10.1137/0722066
  4. Bosworth, W., Huchon, P., and McClay, K., 2005, The Red Sea and Gulf of Aden Basins, J. Afr. Earth Sci., 43, 334-378. https://doi.org/10.1016/j.jafrearsci.2005.07.020
  5. Brigham, E. O., 1988, The fast Fourier Transform and its applications, Prentice Hall, 448.
  6. Brown, G. F., 1972, Tectonic Map of the Arabian Peninsula, US Geological Survey.
  7. Camp, V. E., and Roobol, M. J., 1992, Upwelling asthenosphere beneath western Arabia and its regional implications, J. Geophys. Res., 97, 15255-15271. https://doi.org/10.1029/92JB00943
  8. Chang, S. J., Merino, M., Van der Lee, S., Stein, S., and Stein, C. A., 2011, Mantle flow beneath Arabia offset from the opening Red Sea, Geophys. Res. Lett., 38(4), L04301, doi:10.1029/2010GL045852. https://doi.org/10.1029/2010GL045852
  9. Chang, S. J., and Van der Lee, S., 2011, Mantle plumes and associated flow beneath Arabia and East Africa, Earth Planet. Sci. Lett., 302, 448-454. https://doi.org/10.1016/j.epsl.2010.12.050
  10. Coleman, R. G., 1977, Ophiolites: Ancient Oceanic Lithosphere? Springer-Verlag, 229.
  11. Dziewonski, A., Bloch, S., and Landisman, M., 1969, Technique for the analysis of transient seismic signals, Bull. Seis. Soc. Am., 59(1), 427-444.
  12. Falcon N., 1974. Southern Iran: Zagros Mountains. In: Spencer, A., Ed., Mesozoic-Cenozoic Orogenic Belts, 4, Geol. Soc. Spec. Publ. 199-211. https://doi.org/10.1144/GSL.SP.2005.004.01.11
  13. Garfunkel, Z., and Beyth, M., 2006, Constraints on the structural development of Afar imposed by kinematics of the major surrounding plates, Geol. Soc. Spec. Publ., 259, 23-42. https://doi.org/10.1144/GSL.SP.2006.259.01.04
  14. Herrmann, R. B., and Ammon, C. J., 2002, Computer Programs in Seismology, Version 3.30, Saint Louis University, St. Lousis, Missouri.
  15. Kennett, B. L. N., Sambridge, M. S., and Williamson, P. R., 1988, Subspace methods for large inverse problems with multiple parameter classes, Geophys. J. Int., 94(2), 237-247. https://doi.org/10.1111/j.1365-246X.1988.tb05898.x
  16. Koulakov, I., Burov, E., Cloetingh, S., El Khrepy, S., Al-Arifi, N., and Bushenkova, N., 2016, Evidence for anomalous mantle upwelling beneath the Arabian Platform from travel time tomography inversion, Tectonophysics, 667, 176-188. https://doi.org/10.1016/j.tecto.2015.11.022
  17. McClusky, S., Reilinger, R., Mahmoud, S., Ben Sari, D., and Tealeb, A., 2003, GPS constraints on Africa (Nubia) and Arabia plate motions, Geophys. J. Int., 155, 126-138. https://doi.org/10.1046/j.1365-246X.2003.02023.x
  18. Sepehr, M., and Cosgrove, J. W., 2004, Structural framework of the Zagros fold-thrust belt, Iran, Mar. Pet. Geol., 21(7), 829-843. https://doi.org/10.1016/j.marpetgeo.2003.07.006
  19. Stocklin, J., 1968, Structural history and tectonics of Iran: a review, Am. Assoc. Pet. Geol. Bull., 52(7), 1229-1258.
  20. Stoeser, D. B., and Camp, V. E., 1985, Pan-African Microplate Accretion of the Arabian Shield, Geol. Soc. Am. Bull., 96(7), 817-826. https://doi.org/10.1130/0016-7606(1985)96<817:PMAOTA>2.0.CO;2
  21. Tang, Z., Julia, J., Zahran, H., and Mai, P. M., 2016, The lithospheric shear-wave velocity structure of Saudi Arabia: young volcanism in an old shield, Tectonophysics, 680, 8-27. https://doi.org/10.1016/j.tecto.2016.05.004
  22. Tang, Z., Mai, P. M., Chang, S. J., and Zahran, H., 2018, Evidence for crustal low shear-wave speed in western Saudi Arabia from multi-scale fundamental-mode Rayleigh-wave group-velocity tomography, Earth Planet. Sci. Lett., 495, 24-37. https://doi.org/10.1016/j.epsl.2018.05.011