### 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
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Cynthia J. Sellers
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**
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*Woods Hole Oceanogr. Inst., Woods Hole, MA 02543
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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.]