[1] Seismic reflection profiles shot across the Cascadia forearc show that a 5–15 km thick band of reflections, previously interpreted as a lower crustal shear zone above the subducting Juan de Fuca plate, extends into the upper mantle of the North American plate, reaching depths of at least 50 km. In the extreme western corner of the mantle wedge, these reflectors occur in rocks with P wave ve...

Small geological features manifest themselves in seismic data in the form of diffracted waves, which are fundamentally different from seismic reflections. Using two field data examples and one synthetic example, we demonstrate the possibility of separating seismic diffractions in the data and imaging them with optimally chosen migration velocities. Our criterion for separating reflection and di...

Seismic acquisition footprint generally consists of modulations in recorded amplitudes that are spatially correlated to the surface locations of sources and receivers used in a survey. These amplitude variations obscure the true reflection response of the subsurface. In this study, synthetic seismic data were produced using numerical modelling code written in MATLAB. An “exhaustive” dataset was...

I show that, by estimating local event slopes in prestack seismic reflection data, it is possible to accomplish all common time-domain imaging tasks, from normal moveout to prestack time migration, without the need to estimate seismic velocities or any other attributes. Local slopes contain complete information about the reflection geometry. Once they are estimated, seismic velocities and all o...

The existence of multiple reflections brings difficulty to seismic data processing and interpretation in reflection exploration. Parabolic Radon transform is widely used attenuation because it easily implemented, highly robust efficient. However, finite acquisition aperture causes energy diffusion the domain, which leads residuals. In this paper, we propose a sparse parabolic with nonconvex Lq1...

The current emphasis in seismic stratigraphy has This process of wavelet extraction, followed by the focussed on velocity inversion and the generation of derivation of the reflectivity sequence, allows the the pseudo-acoustic log from the seismic trace. ideal pre-conditioning for seismic velocity inverThere are several published methods on wavelet sion. extraction which invariably make assumpti...

I present the theory of interferometric imaging (II). Interferometric imaging is any algorithm that images crosscorrelated data for the reflectivity or source distribution. As examples, I show that II can image arbitrary reflectivity distributions by migrating ghost reflections in passive seismic data, generalize the receiver-function imaging method used by seismologists, and migrate free-surfa...

Shallow high resolution 2-D and 3-D seismic reflection techniques are assisting in the subsurface delineation of a surface collapsc feature (sinkhole) at Weeks Island. Louisiana. Seismic reflection surveys were conducted in March 1994. Data from walkaway noise tests were used to assist selection of field recording parameters. The top of the salt dome is about 180 ft below ground surface at the ...

The registration of PP and PS images is a process of correlating corresponding seismic reflections in the two images. We use dynamic image warping to automatically estimate a smooth field of vertical shifts. In warping the PS-image with this shift field, we move reflections in the PS-image to match these in the PP-image. The shift field can also be used to compute the Vp/Vs ratio. Examples for ...