Determination of intrinsic attenuation in the oceanic lithosphere-asthenosphere system

We recorded P and S waves traveling through the oceanic lithosphere-asthenosphere system (LAS) using broadband ocean-bottom seismometers in the northwest Pacific, and we quantitatively separated the intrinsic (anelastic) and extrinsic (scattering) attenuation effects on seismic wave propagation to d...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2017-12, Vol.358 (6370), p.1593-1596
Main Authors: Takeuchi, Nozomu, Kawakatsu, Hitoshi, Shiobara, Hajime, Isse, Takehi, Sugioka, Hiroko, Ito, Aki, Utada, Hisashi
Format: Article
Language:English
Subjects:
Anelasticity
Asthenosphere
Broadband
Earthquakes
Energy
Frequency dependence
Lithosphere
Ocean bottom
Plate tectonics
Plates (tectonics)
S waves
Seismic activity
Seismic energy
Seismographs
Surface waves
Tectonics
Thermomechanical properties
Wave attenuation
Wave propagation
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Summary:We recorded P and S waves traveling through the oceanic lithosphere-asthenosphere system (LAS) using broadband ocean-bottom seismometers in the northwest Pacific, and we quantitatively separated the intrinsic (anelastic) and extrinsic (scattering) attenuation effects on seismic wave propagation to directly infer the thermomechanical properties of the oceanic LAS. The strong intrinsic attenuation in the asthenosphere obtained at higher frequency (~3 hertz) is comparable to that constrained at lower frequency (~100 seconds) by surface waves and suggests frequency-independent anelasticity, whereas the intrinsic attenuation in the lithosphere is frequency dependent. This difference in frequency dependence indicates that the strong and broad peak dissipation recently observed in the laboratory exists only in the asthenosphere and provides new insight into what distinguishes the asthenosphere from the lithosphere.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aao3508