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Body waves from a single source area observed in noise correlations at arrival times of reflections from the 410 discontinuity

Body waves from a single source area observed in noise correlations at arrival times of... Abstract Body waves are routinely observed in cross-correlations of ambient noise records from seismic arrays worldwide but it is still poorly understood how the lack of uniform coverage of body wave sources at sea impacts reconstruction of some deep seismic phases such as for example reflections on mantle discontinuities. These difficulties presently hinder a generalization of the extraction of these phases, even though the feasibility of such techniques has been demonstrated previously. In this study we focus on the extraction of P reflections from the 410 discontinuity (Pv410P) using cross-correlations from records of quasi-linear array between Tibet and Himalaya. We demonstrate that in this geographic location and with the network geometry at hand, the noise correlations in the second microseismic peak are during most of the year dominated by a noise source in the north Pacific. The potential Pv410P phase revealed in the stacks of all data and through SVD analysis on a subset of data has an amplitude which is similar to that of cross terms of different body wave phases from the source area, so a positive identification of the Pv410P remains speculative. As the arrival times and apparent velocity of mantle reflected waves are close to those of several cross terms, other diagnostic tools are needed to identify areas and network configurations for which noise correlations can confidently be used to analyse reflections from the mid mantle discontinuities. Seismic noise, Seismic interferometry, Body waves, Composition and structure of the mantle, Asia, Numerical modelling © The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Geophysical Journal International Oxford University Press

Body waves from a single source area observed in noise correlations at arrival times of reflections from the 410 discontinuity

Pedersen, H A; Colombi, A
Geophysical Journal International , Volume Advance Article – May 23, 2018
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Publisher
Oxford University Press
Copyright
© The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society.
ISSN
0956-540X
eISSN
1365-246X
DOI
10.1093/gji/ggy191
Publisher site
See Article on Publisher Site

Abstract

Abstract Body waves are routinely observed in cross-correlations of ambient noise records from seismic arrays worldwide but it is still poorly understood how the lack of uniform coverage of body wave sources at sea impacts reconstruction of some deep seismic phases such as for example reflections on mantle discontinuities. These difficulties presently hinder a generalization of the extraction of these phases, even though the feasibility of such techniques has been demonstrated previously. In this study we focus on the extraction of P reflections from the 410 discontinuity (Pv410P) using cross-correlations from records of quasi-linear array between Tibet and Himalaya. We demonstrate that in this geographic location and with the network geometry at hand, the noise correlations in the second microseismic peak are during most of the year dominated by a noise source in the north Pacific. The potential Pv410P phase revealed in the stacks of all data and through SVD analysis on a subset of data has an amplitude which is similar to that of cross terms of different body wave phases from the source area, so a positive identification of the Pv410P remains speculative. As the arrival times and apparent velocity of mantle reflected waves are close to those of several cross terms, other diagnostic tools are needed to identify areas and network configurations for which noise correlations can confidently be used to analyse reflections from the mid mantle discontinuities. Seismic noise, Seismic interferometry, Body waves, Composition and structure of the mantle, Asia, Numerical modelling © The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Journal

Geophysical Journal International – Oxford University Press

Published: May 23, 2018

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