Open AccessSEISMIC TIME‐CURVES AND DEPTH DETERMINATION.
Author(s) -
Lehmann I.
Publication year - 1937
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1937.tb03734.x
Subject(s) - geology , amplitude , constant (computer programming) , geometry , work (physics) , geodesy , geophysics , mineralogy , mathematics , physics , optics , thermodynamics , computer science , programming language
Summary –It has been shown that the slow gradual increase of velocity which is likely to occur in uniform sedimentary layers gives rise to straight time‐curves such as are usually obtained in prospecting. When depth is determined from straight time‐curves on the assumption that the velocity is constant within the layers, a good approximation to actual depths is obtained provided the increase of the velocity in the layers is small and the separate layers are not very deep. If the velocity increases strongly within a layer we may again obtain straight time‐curves, but if such time‐curves are interpreted on the assumption of constant velocity within separate layers, serious departures from true conditions will be involved. It may be possible to detect a strong gradual increase of velocity by means of amplitude observations, but depth determination remains uncertain. I am greatly indebted to Dr. E. C. Bullard, who has allowed me to become acquainted with his work while yet in progress and who has kindly let me reproduce his records. My thanks are also due to Dr. Harold Jeffreys for various advice.