1 / 13

Introduction to Shear Wave Splitting

Introduction to Shear Wave Splitting. Erin Elliott Guofeng Yuan February 26, 2010. Outline. Concept Definitions History Applications Common Misunderstandings Conclusions . What is Shear Wave Splitting?.

muncel
Download Presentation

Introduction to Shear Wave Splitting

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to Shear Wave Splitting Erin Elliott Guofeng Yuan February 26, 2010

  2. Outline • Concept • Definitions • History • Applications • Common Misunderstandings • Conclusions

  3. What is Shear Wave Splitting? • When a polarized shear-wave enters an anisotropic medium, it splits into two quasi shear-waves (fast and slow).

  4. Shear Wave Splitting (Seismic birefringence) http://garnero.asu.edu/research_images/anis/garnero_splitting.gif

  5. History

  6. Definitions • Microcrack • Azimuthally Aligned • Polarization Diagrams

  7. Microcracks Crack density

  8. Azimuthally Aligned • the angles that the arrivals or waves make with a reference point are all equal. • The waves are approximately parallel: http://en.wikipedia.org/wiki/Azimuth

  9. Polarization Diagrams(Hodograms) • Displays a 2-D projection of the trajectory of a point moving in space. • a cross plot of two components of motion over a time window. http://www.crewes.org/ResearchLinks/ExplorerPrograms/Hodogram/Hodogram.html

  10. Applications • Possible earthquake prediction • for earthquakes M 1.7 to M 7.7 • CO2 Injection mapping • in fractured carbonate reservoirs

  11. Common Misunderstandings • Polarizations of split shear waves are orthogonal • Crack anisotropy always decreases with depth as fluid filled cracks are closed by lithostatic pressure. • Signal-to-noise ratios of shear-wave splitting above small earthquakes can be improved by stacking.

  12. Conclusion • Stress aligned fluid-saturated microcracks are the predominant cause of the nearly universal observations of azimuthally aligned shear wave splitting both in the earth’s crust and in the upper mantle.

  13. Questions?

More Related