In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science
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This unusual book, published to honor the late iconoclast and geologist extraordinaire Warren Bell Hamilton, comprises a diverse, cross-disciplinary collection of bold new ideas in Earth and planetary science. Some chapters audaciously point out all-too-obvious deficits in prevailing theories. Other ideas are embryonic and in need of testing and still others are downright outrageous. Some are doubtless right and others likely wrong. See if you can tell which is which. See if your students can tell which is which. This unique book is a rich resource for researchers at all levels looking for interesting, unusual, and off-beat ideas to investigate or set as student projects.
Teleseismic tomography: Equation one is wrong
Published:May 03, 2022
Bruce R. Julian, Gillian R. Foulger, 2022. "Teleseismic tomography: Equation one is wrong", In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science, Gillian R. Foulger, Lawrence C. Hamilton, Donna M. Jurdy, Carol A. Stein, Keith A. Howard, Seth Stein
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Seismic tomography methods that use waves originating outside the volume being studied are subject to bias caused by unknown structure outside this volume. The bias is of the same mathematical order and similar magnitude as the local-structure effects being studied; failure to account for it can significantly corrupt derived structural models.
This bias can be eliminated by adding to the inverse problem three unknown parameters specifying the direction and time for each incident wave, a procedure analogous to solving for event locations in local-earthquake and whole-mantle tomography. The forward problem is particularly simple: The first-order change in the arrival time at an observation point resulting from a perturbation to the incident-wave direction and time equals the change in the time of the perturbed incident wave at the point where the unperturbed ray entered the study volume. This consequence of Fermat’s principle apparently has not previously been recognized. Published teleseismic tomography models probably contain significant artifacts and need to be recomputed using the more complete theory.