[i] We show that ocean temperature profiles can be accurately recovered using only acoustic methods employed at the sea surface. Using a towed air gun array and a hydrophone streamer, thermohaline boundaries are ensonified at a suite of frequencies and angles, yielding travel time trajectories and reflectivities. These data are inverted via full waveform inversion to estimate sound speed and, s...

This report presents the final results from this contract to analyze the seismicity of the Yakima Fold and Thrust Belt (YFTB) region, Washington (Figure 1). The contract work involved the following: Apply conventional seismic tomography, using the public domain code simul2000 (Thurber and Eberhart-Phillips, 1999), to the YFTB region (121.25°W to 117.5°W and 45.5°N to 47.5°N) dataset of approxim...

[1] We report measurements of long-period P wave polarization (Ppol) in Australia and Tahiti made by combining modeling of the polarization deviation and harmonic analysis. The analysis of the deviation of the horizontal polarization of the P wave as a function of event back azimuth may be used to obtain information about (1) sensor misorientation, (2) dipping discontinuities, (3) seismic aniso...

We elaborate the main points of the wave-equation migration velocity analysis method introduced in a previous report. We analyze its strengths and limitations, and illustrate them using a synthetic example. The inversion results confirm our original expectations, especially with regard to stability and robustness. The main difficulty in recovering a complete velocity perturbation is related to ...

I present a parallel matrix-free framework for frequency-domain seismic modeling, imaging and inversion. The framework provides basic building blocks for designing and testing optimization-based formulations of both linear and non-linear seismic inverse problems. By overloading standard linear-algebra operations, such as matrixvector multiplications, standard optimization packages can be used t...

Thermal convection in the Antarctic and Greenland ice sheets has been dismissed on the grounds that radio-echo stratigraphy is undisturbed for long distances. However, the undisturbed stratigraphy lies, for the most part, above the density inversion in polar ice sheets and therefore does not disprove convection. An echo-free zone is widespread below the density inversion, yet nobody has cited t...

Seismic data recovery from data with missing traces on otherwise regular acquisition grids forms a crucial step in the seismic processing flow. For instance, unsuccessful recovery leads to imaging artifacts and to erroneous predictions for the multiples, adversely affecting the performance of multiple elimination. A non-parametric transform-based recovery method is presented that exploits the c...

In this paper, we propose a frozen Gaussian approximation (FGA)-based multilevel particle swarm optimization (MLPSO) method for seismic inversion of highfrequency wave data. The method addresses two challenges in it: First, the optimization problem is highly non-convex, which makes hard for gradient-based methods to reach global minima. This is tackled by MLPSO which can escape from undesired l...

The difficulties of imaging beneath salt bodies where illumination is poor are well known. In this paper, we present an angle-domain least-squares inversion scheme that regularizes the seismic image, tending to smooth along specified dips. This smoothing is accomplished using steering filters. We show the results of using the regularized inversion with smoothing along the angle axis and along b...