Bulletin of the Seismological Society of America
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Bulletin of the Seismological Society of America; April 1971; v. 61; no. 2; p. 429-456
© 1971 Seismological Society of America
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by BUCHBINDER, G. G. R.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

A velocity structure of the Earth's core

GOETZ G. R. BUCHBINDER

SEISMOLOGY DIVISION EARTH PHYSICS BRANCH DEPARTMENT OF ENERGY, MINES AND RESOURCES, OTTAWA, ONTARIO, Canada

Abstract

Travel times and amplitudes of PKP, P2KP and higher multiple K phases are determined from a worldwide distribution of short-period seismograms. The sources are one explosion in Novaya-Zemlya and seven earthquakes, consisting of one intermediate focus event in the New Hebrides, and deep-focus events in Fiji, Java, Kermadec Islands, and Peru. The data are used to determine a new velocity model of the lowest mantle and the core. In the new velocity model 132, the velocity of the bottom of the mantle is 13.44 km/sec; the core mantle boundary is placed at 2892 ± 2 km. The velocity model of the core produces the PKP caustic B1 at 143° and the P2KP caustic B2 at –125°. A velocity discontinuity of 0.01 km/sec at a depth of 4550 km represents the top of the transition zone to account for the earliest forerunners of PKP. To account for the later forerunners a second discontinuity of 0.02 km/sec is placed at a depth of 4850 km. Since the forerunner data could not be resolved into branches, neither discontinuity is well defined.

The top of the inner core boundary is placed at a depth of 5145 km with an uncertainty of at least 10 km and represents a discontinuity of 0.576 km/sec. Older core models have transition zone discontinuities an order of magnitude larger than those of model 132 with a discontinuity at the inner core boundary of about 1 km/sec. The smaller velocity discontinuities are a result of interpreting the amplitudes and travel times of PKP so that the turning points D and G are located at 120° and 140°, respectively, rather than at 110° and 125° as in previous interpretations.

Amplitude ratios of PKP phases yield an inner core Q of about 400 and amplitude ratios of P3KP, P4KP and P5KP result in an outer core Q of about 4000.




This article has been cited by other articles:


Home page
 Bulletin of the Seismological Society of AmericaHome page
J. Schlittenhardt
Array analysis of core-phase caustic signals from underground nuclear explosions: Discrimination of closely spaced explosions
Bulletin of the Seismological Society of America, February 1, 1996; 86(1A): 159 - 171.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
D. S. Sharrock, I. G. Main, and A. Douglas
Observations of Q from the northwest Pacific subduction zone recorded at teleseismic distances
Bulletin of the Seismological Society of America, February 1, 1995; 85(1): 237 - 253.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
A. C. CHANG and J. R. CLEARY
Precursors to PKKP
Bulletin of the Seismological Society of America, August 1, 1978; 68(4): 1059 - 1079.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
C. WRIGHT
The origin of short-period precursors to PKP
Bulletin of the Seismological Society of America, June 1, 1975; 65(3): 765 - 786.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
G. G. R. BUCHBINDER
Diffraction from the PKP caustic B
Bulletin of the Seismological Society of America, February 1, 1974; 64(1): 33 - 43.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
G. G. R. BUCHBINDER and G. POUPINET
Problems related to PcP and the core-mantle boundary illustrated by two nuclear events
Bulletin of the Seismological Society of America, December 1, 1973; 63(6-1): 2047 - 2070.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
G. G. R. BUCHBINDER, C. WRIGHT, and G. POUPINET
Observations of PKiKP at distances less than 110{degrees}
Bulletin of the Seismological Society of America, October 1, 1973; 63(5): 1699 - 1707.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
A. QAMAR
Revised velocities in the Earth's core
Bulletin of the Seismological Society of America, June 1, 1973; 63(3): 1073 - 1105.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
J. H. WHITCOMB
Asymmetric P'P': An alternative to P'dP' reflections in the uppermost mantle (0 to 110 km)
Bulletin of the Seismological Society of America, February 1, 1973; 63(1): 133 - 143.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
R. D. ADAMS
Multiple inner core reflections from a Novaya Zemlya explosion
Bulletin of the Seismological Society of America, August 1, 1972; 62(4): 1063 - 1071.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
R. DATT and T. G. VARGHESE
Array detection and location of core shadow events
Bulletin of the Seismological Society of America, February 1, 1972; 62(1): 231 - 245.
[Abstract] [PDF]

Home page
 Bulletin of the Seismological Society of AmericaHome page
C. WRIGHT
Array studies of seismic waves arriving between P and PP in the distance range 90{degrees} to 115{degrees}
Bulletin of the Seismological Society of America, February 1, 1972; 62(1): 385 - 400.
[Abstract] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1971 by the Seismological Society of America.