Journal of Seismology

, Volume 17, Issue 2, pp 683–705 | Cite as

Shear wave velocity models retrieved using Rg wave dispersion data in shallow crust in some regions of southern Ontario, Canada

  • Shutian Ma
  • Dariush Motazedian
  • Victor Corchete
Original Article


Many crucial tasks in seismology, such as locating seismic events and estimating focal mechanisms, need crustal velocity models. The velocity models of shallow structures are particularly important in the simulation of ground motions. In southern Ontario, Canada, many small shallow earthquakes occur, generating high-frequency Rayleigh (Rg) waves that are sensitive to shallow structures. In this research, the dispersion of Rg waves was used to obtain shear-wave velocities in the top few kilometers of the crust in the Georgian Bay, Sudbury, and Thunder Bay areas of southern Ontario. Several shallow velocity models were obtained based on the dispersion of recorded Rg waves. The Rg waves generated by an m N 3.0 natural earthquake on the northern shore of Georgian Bay were used to obtain velocity models for the area of an earthquake swarm in 2007. The Rg waves generated by a mining induced event in the Sudbury area in 2005 were used to retrieve velocity models between Georgian Bay and the Ottawa River. The Rg waves generated by the largest event in a natural earthquake swarm near Thunder Bay in 2008 were used to obtain a velocity model in that swarm area. The basic feature of all the investigated models is that there is a top low-velocity layer with a thickness of about 0.5 km. The seismic velocities changed mainly within the top 2 km, where small earthquakes often occur.


Shear wave velocity models Rg wave dispersion Southern Ontario 



This research was supported by the Natural Sciences and Engineering Research Council of Canada under the Strategic Research Networks and Discovery Grant programs. We gratefully acknowledge the constructive comments and suggestions from the Editor-in-Chief, T. Dahm, and reviewers. The seismograms and earthquake catalogs used in this article were retrieved from the Natural Resources Canada official website. The waveform records were processed using SAC2000, redseed and geotool programs.


  1. Båth M (1974) Spectral analysis in geophysics. Elsevier, Amsterdam, p 563Google Scholar
  2. Chourak M, Corchete V, Badal J, Serón FJ, Soria F (2003) Imaging of the near-surface shear-wave velocity structure of the Granada Basin (Southern Spain). Bull Seismol Soc Am 93(1):430–442CrossRefGoogle Scholar
  3. Corchete V, Chourak M, Hussein HM (2007) Shear wave velocity structure of the Sinai Peninsula from Rayleigh wave analysis. Surv Geophys 28:299–324CrossRefGoogle Scholar
  4. Dineva S, Eaton D, Ma S, Mereu R (2007) The October 2005 Georgian Bay (Canada) earthquake sequence: mafic dykes and their role in the mechanical heterogeneity of Precambrian crust. Bull Seismol Soc Am 97(2):457–473CrossRefGoogle Scholar
  5. Dziewonski A, Bloch S, Landisman M (1969) A technique for the analysis of transient seismic signals. Bull Seismol Soc Am 59(1):427–444Google Scholar
  6. Herrmann R, Ammon C (2002) Computer programs in seismology, version 3.30. Saint Louis University, MissouriGoogle Scholar
  7. Jamieson RA, Beaumont C, Nguyen MH, Culshaw NG (2007) Synconvergent ductile flow in variable-strength continental crust: numerical models with application to the western Grenville orogen. Tectonics 26. doi: 10.1029/2006TC002036
  8. Kafka AL, Reiter EC (1987) Dispersion of Rg waves in southeastern Maine: evidence for lateral anisotropy in the shallow crust. Bull Seismol Soc Am 77(3):925–941Google Scholar
  9. Kennett BLN (1983) Seismic wave propagation in stratified media. Cambridge University Press, Cambridge, pp 1–342Google Scholar
  10. Ma S (2010) Focal depth determination for moderate and small earthquakes by modeling regional depth phases sPg, sPmP, and sPn. Bull Seismol Soc Am 100(3):1073–1088CrossRefGoogle Scholar
  11. Ma S, Eaton D (2009) Anatomy of a small earthquake swarm in southern Ontario, Canada. Seismol Res Lett 80:214–223CrossRefGoogle Scholar
  12. Ma S, Eaton D (2011) Combining double-difference relocation with regional depth-phase modelling to improve hypocentre accuracy. Geophys J Int. doi: 10.1111/j.1365-246X.2011.04972
  13. Ma S, Motazedian D (2011) Depth determination of small shallow earthquakes in eastern Canada from maximum power Rg/Sg spectral ratio. J Seismol 1–23. doi: 10.1007/s10950-011-9252-9
  14. Ma S, Motazedian D (2012) Studies on the June 23 2010 north Ottawa M W 5.2 earthquake and vicinity seismicity. J Seismol. doi: 10.1007/s10950-012-9294-7
  15. Randall G (1994) Efficient calculation of complete differential seismograms for laterally homogeneous earth models. Geophys J Int 118:245–254CrossRefGoogle Scholar
  16. Rodi WL, Glover P, Li TMC, Alexander SS (1975) A fast, accurate method for computing group-velocity partial derivatives for Rayleigh and Love modes. Bull Seismol Soc Am 65(5):1105–1114Google Scholar
  17. Stein S, Wysession M (2003) An introduction to seismology, earthquakes, and earth structure. Blackwell, MaldenGoogle Scholar
  18. Waldhauser F, Ellsworth WL (2000) A double-difference earthquake location algorithm: method and application to the northern Hayward fault, California. Bull Seismol Soc Am 90(6):1353–1368CrossRefGoogle Scholar
  19. White DJ, Forsyth DA, Asudeh IA, Carr SD, Wu H, Easton RM, Mereu RF (2000) Seismic-based cross-section across the Grenville Front in Ontario. Can J Earth Sci 37(2–3):183–192CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  • Shutian Ma
    • 1
  • Dariush Motazedian
    • 1
  • Victor Corchete
    • 2
  1. 1.Department of Earth SciencesCarleton UniversityOttawaCanada
  2. 2.Department of Applied PhysicsUniversity of AlmeriaAlmeriaSpain

Personalised recommendations