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SUMMARY:Investigating Earth's deep mantle buoyancy and frequency dependent
  behavior using Earth tides - Harriet Lau\, UC Berkeley
DTSTART:20201028T160000Z
DTEND:20201028T170000Z
UID:TALK151324@talks.cam.ac.uk
CONTACT:Camilla Penney
DESCRIPTION:Earth's mantle is a key component of the Earth system: its cir
 culation drives plate tectonics\, the long-term recycling of Earth's volat
 iles\, and as such\, holds fundamental implications for the Earth's surfac
 e environment.  In order to understand this evolution\, two aspects of the
  mantle must be known: its buoyancy and how it dissipates energy.  For the
  former\, I will discuss how Earth's body tide can provide fresh and indep
 endent constraints on deep mantle buoyancy through a newly developed techn
 ique called _Tidal Tomography_.  This comes at a time when other interesti
 ng and exciting data sets sensitive to deep mantle buoyancy\, e.g.\, Stone
 ley modes\, have been brought to bear\, and we will explore our conclusion
 s in the context of other recent finds. \n\n \n\nAs a complement to this\,
  tidal data also stretch the frequency band across which we can analyze di
 ssipation of the lower mantle.  By combining a selection of normal mode an
 d tidal attenuation data – while implementing the recent advances in ane
 lastic theory relevant to phenomena – we can examine dissipation spannin
 g six orders of magnitude in frequency (from 7 minutes to 18.6 years). We 
 compare these observations with predictions from a laboratory-based model 
 of intrinsic dissipation and our modeling approach incorporates mantle par
 ameters inferred from mantle convection studies.  We find our macroscopic 
 result is consistent with experimental data and resolves a recent discord 
 between wide band attenuation derived from seismic versus geodetic data. W
 e discuss the implications of these results on grain-scale mechanisms of d
 issipation.  To arrive at these conclusions\, theoretical and observationa
 l insights from a wide range of spatio-temporal data (from the micro- and 
 planetary-scale\; from minutes to decades) and disciplines (rock physics\,
  seismology\, and geodynamics) have been combined.\n\nFurther Reading:\n\n
 "https://www.nature.com/articles/nature24452":URL\n\n"https://www.scienced
 irect.com/science/article/abs/pii/S0012821X18307180":URL\n\n*This seminar 
 will be held online. Zoom details will be sent to members of the Earth Sci
 ences department via email. Please contact the organisers if you are outsi
 de the department and would like to attend*\n\n\n
LOCATION:ONLINE - Details to be sent by email
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