Angle-gather migration creates seismic images for different reflection angles at the reflector. We formulate an angle-gather time migration algorithm and study its properties. The algorithm serves as an educational introduction to the angle gather concept. It also looks attractive as a practical alternative to conventional common-offset time migration both for velocity analysis and for AVO/AVA ...

Angle-gather migration creates seismic images for different reflection angles at the reflector. We formulate an angle-gather time migration algorithm and study its properties. The algorithm serves as an educational introduction to the angle gather concept. It also looks attractive as a practical alternative to conventional common-offset time migration both for velocity analysis and for AVO/AVA ...

Wave-equation migration with the velocity of the primaries maps non-diffracted waterbottom multiples to an hyperbola in subsurface-offset-domain-common-image-gathers. Furthermore, for positive surface offsets, the multiples are mapped to non-positive subsurface offsets if sediment velocity is faster than water. The larger the offset in the data space, the larger the subsurface offset and the sh...

BACKGROUND In response to infection, neutrophils are quickly recruited from the blood into inflamed tissues. The interstitial migration of neutrophils is crucial for the efficient capture and control of rapidly proliferating microbes before microbial growth can overwhelm the host's defenses. However, the molecular mechanisms that regulate interstitial migration are incompletely understood. ME...

We show that diffraction stack migration can be used to estimate the distribution of near-surface faults. The assumption is that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. The processing steps are to isolate the back-scattered surface waves, and then migrate them by diffraction migration using the surface wave velocity as the migration vel...

Conventional velocity analysis applied to images produced by wave-equation migration makes use either of moveout information from space-lags, or of focusing information from timelags. However, more robust velocity estimation methods can be designed to take advantage at the same time of the moveout and focusing information provided by the migrated images. Such joint velocity estimation requires ...

Constructing the seismic image in vertical time, as opposed to depth, eliminates the inherent ambiguity of resolving the vertical P -wave velocity from surface seismic data in transversely isotropic media with a vertical axis of symmetry (VTI media). By ray tracing in the space-time (x-τ)-domain, a traveltime map is built by interpolating the traveltime information along the rays onto a regular...

Azimuthal anisotropy is common in layered basins with strong folding and fracturing effects. Traditional processing on individual azimuths usually yields images with inconsistent depths. In this paper, we propose to use an image obtained from one azimuth to constrain the image-space velocity analysis on other azimuths. This method directly tackles the differences in anisotropic parameters among...

Seismic imaging produces images of contrasts in physical parameters in the subsurface, e.g., velocity or impedance. To build such images, a background model describing the wave kinematics in the earth is necessary. In practice, the structural image and background velocity model are unknown and have to be estimated from the acquired data. Migration velocity analysis deals with estimation of the ...

The migration rate of wave-formed ripple marks was investigated using a twodimensional wave flume. Well sorted fine-grained sand (0.2 mm in diameter) was placed on a 1/20-fixed slope and an adjacent part of the horizontal flume bottom. The onshore migration rates of ripples and near-bottom orbital velocities were measured at three sites along the slope with different water depths and at one sit...