The main topic of these lectures is seismic traveltime inversion in 2- and 3-dimensional heterogeneous media. A typical problem is to infer the (isotropic) compressional-wave slowness (reciprocal of velocity) distribution of a medium, given a set of observed first-arrival traveltime between sources and receivers of known location within the medium. This problem is common for crosshole seismic transmission tomography imaging a 2-D region between vertical boreholes in oil field applications. We also consider the problem of inverting for wave slowness when the absolute traveltimes are not known, as is normally the case in earthquake seismology.

"Manuscript date: November 1990." "UCRL-LR-105358." Includes bibliographical references.