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The origin of deep ocean microseisms in the North Atlantic Ocean

Kedar, Sharon and Longuet-Higgins, Michael and Webb, Frank and Graham, Nicholas and Clayton, Robert and Jones, Cathleen (2008) The origin of deep ocean microseisms in the North Atlantic Ocean. Proceedings of the Royal Society A: Mathematical, physical, and engineering sciences, 464 (2091). pp. 777-793. ISSN 1364-5021. https://resolver.caltech.edu/CaltechAUTHORS:20121001-092904179

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Abstract

Oceanic microseisms are small oscillations of the ground, in the frequency range of 0.05–0.3 Hz, associated with the occurrence of energetic ocean waves of half the corresponding frequency. In 1950, Longuet-Higgins suggested in a landmark theoretical paper that (i) microseisms originate from surface pressure oscillations caused by the interaction between oppositely travelling components with the same frequency in the ocean wave spectrum, (ii) these pressure oscillations generate seismic Stoneley waves on the ocean bottom, and (iii) when the ocean depth is comparable with the acoustic wavelength in water, compressibility must be considered. The efficiency of microseism generation thus depends on both the wave frequency and the depth of water. While the theory provided an estimate of the magnitude of the corresponding microseisms in a compressible ocean, its predictions of microseism amplitude heretofore have never been tested quantitatively. In this paper, we show a strong agreement between observed microseism and calculated amplitudes obtained by applying Longuet-Higgins' theory to hindcast ocean wave spectra from the North Atlantic Ocean. The calculated vertical displacements are compared with seismic data collected at stations in North America, Greenland, Iceland and Europe. This modelling identifies a particularly energetic source area stretching from the Labrador Sea to south of Iceland, where wind patterns are especially conducive to generating oppositely travelling waves of same period, and the ocean depth is favourable for efficient microseism generation through the ‘organ pipe’ resonance of the compression waves, as predicted by the theory. This correspondence between observations and the model predictions demonstrates that deep ocean nonlinear wave–wave interactions are sufficiently energetic to account for much of the observed seismic amplitudes in North America, Greenland and Iceland.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1098/rspa.2007.0277 DOIArticle
http://rspa.royalsocietypublishing.org/content/464/2091/777PublisherArticle
ORCID:
AuthorORCID
Clayton, Robert0000-0003-3323-3508
Additional Information:© 2008 The Royal Society. Received 17 October 2007; Accepted 11 December 2007. The authors wish to thank Dr Robert Guza of the Scripps Institution of Oceanography and Dr. Ernesto Rodriguez of the Jet Propulsion Laboratory, California Institute of Technology, for their insights and suggestions. They also wish to thank Dr Hiroo Kanamori of the Caltech Seismological Laboratory for his helpful comments. Maps were generated using the generic mapping tools (GMTs) software package. Seismic data were analysed using Lawrence Livermore National Laboratory’s Seismic Analysis Code (SAC). Seismic data were obtained through the Incorporated Research Institutions of Seismology (IRIS) database and the Canadian National Waveform Archive (NWFA). Data from the following networks were used: Global Seismograph Network (GSN), United States National Seismic Network, the International Deployment of Accelerometers (IDA), the Canadian National Seismograph Network (CNSN), GEOFON, the Caltech Regional Seismic Network and the Berkeley Digital Seismograph Network. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration and funded through the internal Research and Technology Development Program.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
JPL Internal Research and Technology Development ProgramUNSPECIFIED
Subject Keywords:microseisms; wave–wave interaction; acoustic resonance; wave model; Stoneley waves
Issue or Number:2091
Record Number:CaltechAUTHORS:20121001-092904179
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121001-092904179
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34577
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:01 Oct 2012 21:14
Last Modified:03 Oct 2019 04:20

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