Seismic structure using body wave arrivals at SOSUS hydrophone arrays

1996 ◽  
Vol 100 (4) ◽  
pp. 2639-2639
Author(s):  
Philip D. Slack ◽  
Christopher G. Fox ◽  
Robert P. Dziak
Keyword(s):  
Body Wave ◽  
Seismic Structure

scholarly journals Upper mantle seismic structure beneath central East Antarctica from body wave tomography: Implications for the origin of the Gamburtsev Subglacial Mountains

2013 ◽  
Vol 14 (4) ◽  
pp. 902-920 ◽  
Author(s):  
Andrew J. Lloyd ◽  
Andrew A. Nyblade ◽  
Douglas A. Wiens ◽  
Samantha E. Hansen ◽  
Masaki Kanao ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Body Wave ◽  
East Antarctica ◽  
Seismic Structure ◽  
Wave Tomography

scholarly journals Bayesian inference of Earth's radial seismic structure from body-wave traveltimes using neural networks

2013 ◽  
Vol 195 (1) ◽  
pp. 408-422 ◽  
Author(s):  
Ralph W. L. de Wit ◽  
Andrew P. Valentine ◽  
Jeannot Trampert
Keyword(s):  
Neural Networks ◽  
Bayesian Inference ◽  
Body Wave ◽  
Seismic Structure

Observing the signature of the magnetic field's behaviour in the radial variation of inner core anisotropy

2020 ◽  
Author(s):  
Janneke de Jong ◽  
Lennart de Groot ◽  
Arwen Deuss
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Seismic Anisotropy ◽  
Inner Core ◽  
Body Wave ◽  
Outer Core ◽  
Core Structure ◽  
Reversal Rate ◽  
Seismic Structure ◽  
The Magnetic Field

<p>The release of latent heat and lighter materials during inner core solidification is the driving force of the liquid iron flow in the outer core which generates the Earth's magnetic field. It is well known that the behaviour of the magnetic field varies over long time scales. Two clearly identifiable regimes are recognized, (i) superchrons and (ii) periods of hyperactivity (Biggin et al. 2012). Superchrons are characterized by an exceptionally low reversal rate of the magnetic pole and are associated with a low core mantle boundary (CMB) heat flux. Hyperactive periods are defined by a high reversal rate and have a high CMB heat flux.</p><p>Here we investigate whether the occurrence of these two regimes is related to radial variations in inner core seismic structure. Using seismic body-wave observations of compressional PKIKP-waves (Irving & Deuss 2011, Waszek & Deuss 2011, Lythgoe et al. 2013)., we construct a model of inner core anisotropy by comparing the difference between travel times for polar and equatorial rays. Anisotropy is the directional dependence of wave velocity and is determined by the structure of iron crystals in the inner core, hence changes in seismic anisotropy are due to changes in inner core crystal texture. We invert for radial changes in anisotropy while allowing for lateral variations and find that a model of the inner core containing five layers best fits our data. The model contains an isotropic uppermost inner core and four deeper layers with varying degrees of anisotropy.</p><p>Texture differences of the inner core iron crystals have been linked to changes in the solidification process of the inner core (Bergman et al. 2005), i.e. the motor of outer core flow. Therefore, the observed anisotropy variation, caused by variations of inner core solidification, might be related to changes in the behaviour of the magnetic field. Using an inner core growth model (Buffett et al. 1996) we convert depth to time for a range of inner core nucleation ages between 3.0 and 0.5 Ga (Olsen 2016). We find a remarkable correlation between the solidification time of the seismically observed layers and the occurrence of the magnetic regimes for two inner core ages; one with a nucleation at 1.4 Ga and one at 0.6 Ga, corresponding to an average CMB heat flux of 7.6 TW and 16.7 TW respectively.</p><p>Although we currently cannot differentiate between these two inner core ages considering our results alone, they do show that a relation between inner core structure and the behaviour of the magnetic field is possible, and suggest that seismic observations of inner core structure might provide new and independent insights into the magnetic field and its history.</p>

Blunt-body wave drag reduction using focused energy deposition

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 460-467 ◽  
Author(s):  
David Riggins ◽  
H. F. Nelson ◽  
Eric Johnson
Keyword(s):  
Drag Reduction ◽  
Energy Deposition ◽  
Blunt Body ◽  
Body Wave ◽  
Wave Drag ◽  
Wave Drag Reduction
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