1 / 76

Spherical Earth mode and synthetic seismogram computation

This document provides an in-depth exploration of the MINEOS code package for spherical Earth mode analysis and synthetic seismogram generation. It covers mode eigenfrequency and eigenfunction calculations, with detailed algorithms for toroidal modes and the generation of Green's functions for point sources. The synthesis of seismic data, including decaying cosinusoids for different mode types (spheroidal, radial, toroidal), is discussed with applications to real data modeling. The text provides methodologies for constructing complete synthetic seismograms, emphasizing diffraction and time-reduced data analysis.

meriel
Télécharger la présentation

Spherical Earth mode and synthetic seismogram computation

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. Spherical Earth mode and synthetic seismogram computation Guy Masters CIG-2006

  2. MINEOS code package • mineos_bran: does mode eigenfrequency and eigenfunction calculation -- this is where all the work is! • eigcon: massages eigenfunctions for greens function calculation • green: computes greens functions for a point source • syndat: makes synthetics for double-couple or moment tensor sources

  3. Some background on modes

  4. Seismogram is a sum of decaying cosinusoids

  5. Spheroidal Radial Toroidal

  6. Can model real data Bolivia, T>120 sec

  7. Complete synthetics -- includes diffraction etc. Distance SH, T>5sec Reduced time

  8. Basic equations (now for the fun stuff!)

  9. Constitutive relationship

  10. Toroidal modes

  11. (W is scalar for displacement, T is scalar for traction) Note that matrix does not depend on m

  12. Algorithm for toroidal modes • Choose harmonic degree and frequency • Compute starting solution for (W,T) • Integrate equations to top of solid region • Is T(surface)=0? No: go change frequency and start again. Yes: we have a mode solution

  13. T(surface) for harmonic degree 1

  14. (black dots are observed modes)

  15. (black dots are observed modes)

  16. Complete synthetics -- includes diffraction etc. Distance SH, T>5sec Reduced time

  17. Radial and Spheroidal modes

  18. Only 14 distinct non-zero elements of A

  19. (Solution follows that of toroidal modes)

  20. (gravity term corresponds to a frequency of about 0.4mHz)

  21. Spheroidal modes

  22. Minors (at last) • To simplify matters, we will consider the spheroidal mode equations in the Cowling approximation where we include all buoyancy terms but ignore perturbations to the gravitational potential

More Related