CaltechAUTHORS
  A Caltech Library Service

Dynamic origins of seismic wavespeed variation in D"

Bower, Dan J. and Gurnis, Michael and Sun, Daoyuan (2013) Dynamic origins of seismic wavespeed variation in D". Physics of the Earth and Planetary Interiors, 214 (1). pp. 74-86. ISSN 0031-9201. http://resolver.caltech.edu/CaltechAUTHORS:20130222-112422781

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20130222-112422781

Abstract

The D″ discontinuity is defined by a seismic velocity increase of 1–3% about 250 km above the core–mantle boundary (CMB), and is mainly detected beneath locations of inferred paleosubduction. A phase change origin for the interface can explain a triplicated arrival observed in seismic waveform data and is supported by the recent discovery of a post-perovskite phase transition. We investigate the interaction of slabs, plumes, and the phase change within D″ in 2-D compressible convection calculations, and predict waveform complexity in synthetic seismic data. The dynamic models produce significant thermal and phase heterogeneity in D″ over small distances and reveal a variety of behaviors including: (1) distinct pPv blocks separated by upwellings, (2) notches at the top of a pPv layer caused by plume heads, (3) regions of Pv embedded within a pPv layer due to upwellings. Advected isotherms produce complicated thermal structure that enable multiple crossings of the phase boundary. Perturbations to S, SdS, and ScS arrivals (distances <84 degrees) are linked to the evolutionary stage of slabs and plumes, and can be used to determine phase boundary height and velocity increase, volumetric wavespeed anomaly beneath the discontinuity, and possibly the lengthscale of slab folding near the CMB. Resolving fine-scale structure beneath the interface requires additional seismic phases (e.g., Sd, SKS) and larger distances (>80 degrees).


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.pepi.2012.10.004DOIArticle
http://www.sciencedirect.com/science/article/pii/S0031920112001732PublisherArticle
ORCID:
AuthorORCID
Gurnis, Michael0000-0003-1704-597X
Sun, Daoyuan0000-0003-4461-4664
Additional Information:© 2012 Elsevier B.V. Received 31 May 2012. Received in revised form 7 October 2012. Accepted 8 October 2012. Available online 23 October 2012. Edited by George Helffrich. We thank the Computational Infrastructure for Geodynamics (CIG) for distributing CitcomS, Don Helmberger for helpful discussions, and Jennifer M. Jackson for comments. We also thank Allen K. McNamara and an anonymous reviewer for constructive comments. This work was supported by NSF Grant EAR-0855815, and D.S. was supported by a CIW/DTM postdoctoral fellowship. Figures were produced using GMT (Wessel and Smith, 1998).
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-0855815
CIW/DTM postdoctoral fellowshipUNSPECIFIED
Subject Keywords:D″ triplication; Core–mantle boundary; Post-perovskite; Plumes; Slabs; Mantle convection
Record Number:CaltechAUTHORS:20130222-112422781
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130222-112422781
Official Citation:Dan J. Bower, Michael Gurnis, Daoyuan Sun, Dynamic origins of seismic wavespeed variation in, Physics of the Earth and Planetary Interiors, Volume 214, January 2013, Pages 74-86, ISSN 0031-9201, 10.1016/j.pepi.2012.10.004. (http://www.sciencedirect.com/science/article/pii/S0031920112001732)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37081
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:22 Feb 2013 19:37
Last Modified:02 Oct 2017 18:53

Repository Staff Only: item control page