The principal source of information about the structure of the core comes from seismology and the spherically averaged structure is now quite well known. Both long-period (free oscillation) and short-period (body wave) seismology have contributed to our understanding of core structure. A detailed review of work through the early 1970s can be found in Jacobs (1975) so we concentrate on later developments in this article.
The basic structure of the core was known by the late 1930s. Using travel time information, Lehmann had postulated a high velocity inner core in 1936 and the distribution of compressional velocity throughout the core was quite accurately determined by both H. Jeffreys and B. Gutenberg in the late 1930s. Modern travel time analyses use many thousands of measurements. For example, travel time measurements of core phases collected by the I.S.C. are plotted in Fig. 1. The branches of PKP are clearly defined as are SKS and, to a lesser extent, SKKS (which are essential to...
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© 1989 Van Nostrand Reinhold
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Masters, G. (1989). Earth's core: structure . In: Geophysics. Encyclopedia of Earth Science. Springer, Boston, MA. https://doi.org/10.1007/0-387-30752-4_12
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