ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

1pAO8. Simultaneous reconstruction of velocity structure and boundary geometry in crosshole tomography.

Subramaniam D. Rajan

Henry Laible

Cynthia J. Sellers

Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

In recent years, crosshole tomography has been used to infer the velocity structure in the earth's interior, ocean sediments, and in sea ice. In all cases, velocity estimates were obtained from travel time data for the earliest arrival. In many instances, the field measurements contain not only the information about this direct path but also about paths that have interacted with the boundaries. If one were to use the information contained in such boundary reflected paths, the resolution of the estimates could be considerably improved. This, however, implies that one knows the boundary geometry, which is generally not the case. An approach that one can take is to jointly estimate the boundary geometry and the velocity structure in the material. Different approaches that can be used to implement this idea and evaluate the method using synthetic data and field data are presented. [Work supported by ONR.]