The fidelity of depth seismic imaging depends on the accuracy of the velocity models used for wavefield reconstruction. Models can be decomposed in two components corresponding to large scale and small scale variations. In practice, the large scale velocity model component can be estimated with high accuracy using repeated migration/tomography cycles, but the small scale component cannot. When ...

Alison E. Malcolm,1 Bjørn Ursin2 and Maarten V. de Hoop3 1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA. E-mail: [email protected] 2Norwegian University of Science and Technology (NTNU), Department of Petroleum Engineering and Applied Geophysics, S. P Andersensvei 15A, NO-7491 Trondheim, Norway 3Center for Computational and App...

An initial study is performed in which dynamically focused Gaussian beams are investigated for seismic imaging. Focused Gaussian beams away from the source and receiver plane allow the narrowest and planar portions of the beams to occur at the depth of a specific target structure. To match the seismic data, quadratic phase corrections are required for the local slant stacks of the surface data....

Wavefield extrapolation by spatially variable phase shift is currently a migration tool of importance. In this paper, we present a new prestack seismic migration algorithm using the Gabor transform with application to the Marmousi acoustic dataset. The imaging results show a very promising depth imaging algorithm, which is competitive with the best depth imaging algorithms. The Gabor depth imag...

The nature of failure in earthquakes is one of the most fundamental questions in geophysics. We approach this problem using near-source seismic recordings of strongground motion to image the rupture process of earthquakes. We apply the technique to three well-recorded earthquakes in California and interpret the results in terms of earthquake rupture dynamics. To calculate theoretical seismogram...

Benchmarks of our “production” codes show that Pentium-based multi-processors computers running the Linux operating system are attractive options for SEP’s next computational server(s). A four-processor SGI 1400 L (500 Mhz Pentium III Xeon) has consistently performed as well as, or better than, our SGI Origin 200 (180 Mhz R10000). We used the Portland Group’s pgf90 compiler to compile our bench...

A novel imaging process, referred to as vector image isochron (VII) migration, is specifically designed to reduce artifacts caused by arrays with limited apertures. By examining the assumptions behind generalized Radon transform (GRT) migration, a new approach is found which identifies and suppresses array artifacts, based on the array geometry and the migration earth model. The new method work...

Detailed seismic modeling and imaging of Earth’s deep interior is providing key information about lower-mantle structures and processes, including heat flow across the core-mantle boundary, the configuration of mantle upwellings and downwellings, phase equilibria and transport properties of deep mantle materials, and mechanisms of core-mantle coupling. Multichannel seismicwave analysismethods t...

Geophysical inverse problems typically involve a trade off between data misfit and some prior. Pareto curves trace the optimal trade off between these two competing aims. These curves are commonly used in problems with two-norm priors where they are plotted on a log-log scale and are known as L-curves. For other priors, such as the sparsity-promoting one norm, Pareto curves remain relatively un...