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Elsevier, Tectonophysics, 1-4(388), p. 225-238

DOI: 10.1016/j.tecto.2004.04.031

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Imaging low-velocity anomalies with the aid of seismic tomography

Journal article published in 2004 by I. Flecha, D. Martí ORCID, R. Carbonell, J. Escuder Viruete, A. Pérez Estaún
This paper is available in a repository.
This paper is available in a repository.

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Data provided by SHERPA/RoMEO

Abstract

Theoretical considerations (Snell's law) suggest that low-velocity fanomalies are undersampled and therefore should be poorly resolved by inversion schemes based on ray-tracing methods. A synthetic study considering a 40×20 m low-velocity anomaly (300 m/s) placed at the center of a 400×50 m block with gradient background velocity model (from 3000 m/s at the surface to 4000 m/s at the base) indicates that the low ray density in ray-tracing coverage diagrams of tomographic inversion studies can be used as evidence for the existence of low-velocity anomalies. Combined normal incidence seismic reflection images and the velocity models obtained by tomographic inversions of first-arrival travel times form an efficient scheme to resolve low-velocity anomalies such as fracture zones. Furthermore, the velocity models derived from tomographic inversions are used in a wave equation datuming algorithm to account for statics caused by a strongly laterally variable shallow surface (weathering) layer and provide seismic reflection images of fracture zones (low-velocity anomaly) within a granitic pluton.