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Seismic imaging of the Waltham Canyon fault, California: comparison of ray‐theoretical and Fresnel volume prestack depth migration

Bulletin of the Seismological Society of America

By:
, , , and
DOI: 10.1785/0120110338

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Abstract

Near‐vertical faults can be imaged using reflected refractions identified in controlled‐source seismic data. Often theses phases are observed on a few neighboring shot or receiver gathers, resulting in a low‐fold data set. Imaging can be carried out with Kirchhoff prestack depth migration in which migration noise is suppressed by constructive stacking of large amounts of multifold data. Fresnel volume migration can be used for low‐fold data without severe migration noise, as the smearing along isochrones is limited to the first Fresnel zone around the reflection point. We developed a modified Fresnel volume migration technique to enhance imaging of steep faults and to suppress noise and undesired coherent phases. The modifications include target‐oriented filters to separate reflected refractions from steep‐dipping faults and reflections with hyperbolic moveout. Undesired phases like multiple reflections, mode conversions, direct P and S waves, and surface waves are suppressed by these filters. As an alternative approach, we developed a new prestack line‐drawing migration method, which can be considered as a proxy to an infinite frequency approximation of the Fresnel volume migration. The line‐drawing migration is not considering waveform information but requires significantly shorter computational time. Target‐oriented filters were extended by dip filters in the line‐drawing migration method. The migration methods were tested with synthetic data and applied to real data from the Waltham Canyon fault, California. The two techniques are applied best in combination, to design filters and to generate complementary images of steep faults.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Seismic imaging of the Waltham Canyon fault, California: comparison of ray‐theoretical and Fresnel volume prestack depth migration
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120110338
Volume
103
Issue:
1
Year Published:
2013
Language:
English
Publisher:
Seismological Society of America
Publisher location:
El Cerrito, CA
Contributing office(s):
Earthquake Science Center
Description:
13 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of the Seismological Society of America
First page:
340
Last page:
352
Country:
United States
State:
California
Other Geospatial:
Waltham Canyon