Waveform tomography imaging of deep crustal faults - Application to Nankai subduction zone

R. Kamei, R. G. Pratt, T. Tsuji

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In many areas the geological interpretation of seismic images can benefit from quantitative, high resolution velocity images. Waveform Tomography can yield the appropriate images provided the input data contain large offsets and low frequencies, such as those available from a suite of Ocean Bottom Seismographs (OBSs). We provide an illustration in the Nankai subduction zone, where a full interpretation requires both the delineation of detailed crustal fault structures and a quantitative velocity map. Previous prestack migrations have revealed key structures, including a megasplay fault, and two distinctive low velocity zones. However the migration sections are negatively affected by the influence of the sea bottom topographic relief. In this study we applied acoustic Waveform Tomography to the OBS data using the traveltime tomography to provide a suitable starting model; synthetic wavefields generated from the final model reproduced wide-angle reflections from the megasplay fault. Our image clearly delineated major geological features including the megasplay fault, thrusts within the accretionary prisms, and an apparent connectivity of two low velocity zones. By comparing the image with a slice from the 3D migration volume, we confirmed the reliability of our image, and the improvement enabled by the use of wide-angle data with Waveform Tomography.

Original languageEnglish
Title of host publicationSociety of Petroleum Engineers - 73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011 - Incorporating SPE EUROPEC 2011
PublisherSociety of Petroleum Engineers
Pages5340-5344
Number of pages5
ISBN (Print)9781617829666
Publication statusPublished - Jan 1 2011
Externally publishedYes

Publication series

Name73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011
Volume7

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

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    Kamei, R., Pratt, R. G., & Tsuji, T. (2011). Waveform tomography imaging of deep crustal faults - Application to Nankai subduction zone. In Society of Petroleum Engineers - 73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011 - Incorporating SPE EUROPEC 2011 (pp. 5340-5344). (73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011; Vol. 7). Society of Petroleum Engineers.