S (Solid Earth Sciences ) » S-IT Science of the Earth's Interior & Techtonophysics
[S-IT24] Attenuation from crust to core: in situ experiments, observaions and implications
Sun. May 26, 2019 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)
convener:Konishi Kensuke(Institute of Earth Sciences, Academia Sinica), Ikuo Katayama(Department of Earth and Planetary Systems Science, Hiroshima University), Takashi Yoshino(Institute for Planetary Materials, Okayama University), Alexandre Schubnel(CNRS)
Most tomographic studies have been focused upon drawing maps of seismic velocity (SV) structures based on seismic data, with the ultimate goal of learning more about the structure and the composition of the mantle. Another key physical property that is accessible from seismic data is seismic attenuation (SA). Due to complications in isolating its intrinsic causes - e.g. local physical changes - and its extrinsic contributions - mainly scattering and other wave-propagation effects - SA has been underutilized. Yet, advances in waveform inversion have in association with recent enhancements of data permitted for a finer, more comprehensive determination of SA, opening the way to structural interpretations.
Difficulties in classifying and modelling the possible causes of intrinsic SA - e.g. temperature, melt, volatiles, and grain size - have also been raised. Increasingly, theoretical and experimental mineral physics have come to document the relationship between the behavior of SA and an assortment of other phenomena - most particularly, partial melt. These results can subsequently be used interpret seismological observations.
Seismic attenuation is critically implicated in structure, composition, and in fine mantle dynamics at the local, regional, and global scales. It may be used to constrain the existence of water in the transition zone; the presence of melt in various regions - for instance around subduction zones; and in the temperature field of the deep mantle - which would, in turn, help to resolve the chemical contribution to SV observed in this region.
In this session, we would like to discuss aspects of mantle attenuation, with the aim of sharing the current state of all relevant fields of study. We welcome contributions from different fields - in particular, from seismology, mineral physics, and geodynamics, as these may advance our mutual comprehension of SA and its implications; and lay the groundwork for future research and applications thereof.
*Anselme F. E. Borgeaud1,2, Frederic Deschamps1, Kensuke Konishi1, Kenji Kawai2, Robert J. Geller2 (1.Institute of Earth Sciences, Academia Sinica, 2.Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo)