<i>An Introduction to the Theory of Seismology</i>

Bullen, K. È.

doi:10.1063/1.3051239

Cited by 214 publications

(305 citation statements)

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“…As discussed by Bullen (1963), incident P/SV energy will reflect from the free surface primarily as SV waves for a fairly wide range of incident angles, roughly 2-60 ø, while incident P waves will reflect primarily as P for nearly vertical incidence. Calculations of horizontal eigenfunctions for Rayleigh waves in a layered half-space also show that the P/SV ratio is generally less than 1 (e.g., Aki and Richards, 1980).…”

Section: Discussionmentioning

confidence: 99%

On the variability of aftershock ground motions in the San Fernando Valley

Hough

Dietel

Glassmoyer

et al. 1995

Geophysical Research Letters

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Section: Discussionmentioning

confidence: 99%

On the variability of aftershock ground motions in the San Fernando Valley

Hough

Dietel

Glassmoyer

et al. 1995

Geophysical Research Letters

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“…The problem is complicated by the suspected presence of the D" layer at the base of the mantle; its variable mechanical and chemical properties make it difficult to separate the effects of D" and CMB topography [Anderson, 1989;Bullen, 1963;Doornbos, 1980;Gubbins, 1989;Gudmundsson et al, 1990;Clayton, 1991, 1992;Haddon, 1982;Hager et al, 1985;Hager and Richards, 1989;Jacobs, 1987a;Jeanloz, 1990;Knittle and Jeanloz, 1991;Loper, 1991;Morelli and Dziewonski, 1987]. Determinations of the amplitude and phase of the free-core nutation lead to an estimate of 0.5 km of excess ellipticity at the CMB [Babcock and Wilkins, 1988;Gwinn et al, 1986;Herring et al, 1985;Kinoshita and Suchay, 1990;Reid and Moran, 1988;Wahr, 1988].…”

Section: Topooraphy Of the Core-mantle Boundarymentioning

confidence: 99%

Topographic Core-Mantle Coupling and Fluctuations in the Earth's Rotation

Hide¹,

Clayton

Hager

et al. 2013

Relating Geophysical Structures and Processes: The Jeffreys Volume

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Astronomically-determined irregular fluctuations in the Earth's rotation vector on decadal time scales can be used to estimate the fluctuating torque on the lower surface of the Earth's mantle produced by magnetohydrodynamic flow in the underlying liquid metallic core. A method has been proposed for testing the hypothesis that the torque is due primarily to fluctuating dynamic pressure forces acting on irregular topographic features of the core-mantle boundary and also on the equatorial bulge. The method exploits (a) geostrophically-constrained models of fluid motions in the upper reaches of the core based on geomagnetic secular variation data, and (b) patterns of the topography of the CMB based on the mantle flow models constrained by data from seismic tomography, determinations of long wavelength anomalies of the Earth's gravitational field and other geophysical and geodetic data According to the present study, the magnitude of the axial component of the torque implied by determinations of irregular changes in the length of the day is compatible with models of the Earth's deep interior characterized by the presence of irregular CMB topography of effective "height" no more than about 0.5km (about 6% of the equatorial bulge) and strong horizontal variations in the properties of the D" layer at the base of the mantle. The investigation is now being extended to cover a wider range of epochs and also the case of polar motion on decadal time scales produced by fluctuations in the equatorial components of the torque. lNTRODUCfiONElectric currents generated in the Earth's liquid metallic core are responsible for the main geomagnetic field and its secular changes [see Jacobs, 1987ab;Melchior, 1986;Moffatt, 1978a] are produced by dynamo action involving irregular magnetohydrodynamic flow in the core. Concomitant dynamical stresses acting on the overlying mantle are invoked in the interpretation of the so-called "decadal" fluctuations in the rotation of the "solid Earth" (mantle, crust and cryosphere). Studies of these rotational manifestations of core motions bear directly on investigations of the structure, composition and dynamics of the Earth's deep interior

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“…Algorithms are needed for automatically detecting the onset of a strong earthquake and thence shutting down a nuclear reactor at high risk. General references providing basic seismological background include Aki and Richards [1], Bullen and Bolt [10], and Bolt [5].…”

Section: Problemsmentioning

confidence: 99%