Traveltime tomographic inversion with simultan
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  • journal_title:Geophysics
  • Contributor:Ari Tryggvason ; Cedric Schmelzbach ; Christopher Juhlin
  • Publisher:Society of Exploration Geophysicists
  • Date:2009-
  • Format:text/html
  • Language:en
  • Identifier:10.1190/1.3240931
  • journal_abbrev:Geophysics
  • issn:0016-8033
  • volume:74
  • issue:6
  • firstpage:WCB25
  • section:TRAVELTIME TOMOGRAPHY
摘要

We have developed a first-arrival traveltime inversion scheme that jointly solves for seismic velocities and source and receiver static-time terms. The static-time terms are included to compensate for varying time delays introduced by the near-surface low-velocity layer that is too thin to be resolved by tomography. Results on a real data set consisting of picked first-arrival times from a seismic-reflection 2D/3D experiment in a crystalline environment show that the tomography static-time terms are very similar in values and distribution to refraction-static corrections computed using standard refraction-statics software. When applied to 3D seismic-reflection data, tomography static-time terms produce similar or more coherent seismic-reflection images compared to the images using corrections from standard refraction-static software. Furthermore, the method provides a much more detailed model of the near-surface bedrock velocity than standard software when the static-time terms are included in the inversion. Low-velocity zones in this model correlate with other geologic and geophysical data, suggesting that our method results in a reliable model. In addition to generally being required in seismic-reflection imaging, static corrections are also necessary in traveltime tomography to obtain high-fidelity velocity images of the subsurface.