HR: 09:36h
AN: DI51B-09 [Abstracts]
TI: Self-consistent Synthetic Mantle Discontinuities From Joint Modeling of Geodynamics and Mineral Physics and Their Effects on the 3D Global Wave Field
AU: * Schuberth, B
EM: mail@bernhard-schuberth.de
AF: Dept. of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich,
Theresienstr. 41, Munich, 80333, Germany
AU: Piazzoni, A
EM: antonio.piazzoni@geophysik.uni-muenchen.de
AF: Dept. of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich,
Theresienstr. 41, Munich, 80333, Germany
AU: Bunge, H
EM: bunge@lmu.de
AF: Dept. of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich,
Theresienstr. 41, Munich, 80333, Germany
AU: Igel, H
EM: igel@geophysik.uni-muenchen.de
AF: Dept. of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich,
Theresienstr. 41, Munich, 80333, Germany
AU: Steinle-Neumann, G
EM: g.steinle-neumann@uni-bayreuth.de
AF: Bavarian Research Institute of Experimental Geochemistry and Geophysics, University of
Bayreuth, Universitätsstraße 30, Bayreuth, 95440, Germany
AU: Moder, C
EM: mail@christoph-moder.de
AF: Dept. of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich,
Theresienstr. 41, Munich, 80333, Germany
AU: Oeser, J
EM: jens.oeser@geophysik.uni-muenchen.de
AF: Dept. of Earth and Environmental Sciences, Ludwig-Maximilians-University Munich,
Theresienstr. 41, Munich, 80333, Germany
AB:
Our current understanding of mantle structure and dynamics is to a large part based on inversion of seismic data
resulting in tomographic images and on direct analysis of a wide range of seismic phases such as Pdiff, PcP,
ScS
SdS etc. For solving inverse problems, forward modeling is needed to obtain a synthetic dataset for a given set of
model parameters. In this respect, great progress has been made over the last years in the developement of
sophisticated numerical full waveform modeling tools. However, the main limitation in the application of
this new class of techniques for the forward problem of seismology is the lack of accurate predictions of
mantle heterogeneity that allow us to test hypotheses about Earth's mantle. Such predictive models should
be based on geodynamic and mineralogical considerations and derived independently of seismological
observations.
Here, we demonstrate the feasibility of joining forward simulations from geodynamics, mineral physics and
seismology
to obtain earth-like seismograms. 3D global wave propagation is simulated for dynamically consistent thermal
structures
derived from 3D mantle circulation modeling (e.g. Bunge et al. 2002), for which the temperatures are converted to
seismic velocities using a recently published, thermodynamically self-consistent mineral physics approach
(Piazzoni et al. 2007). Assuming a certain, fixed mantle composition (e.g. pyrolite) our mineralogic modeling
algorithm
computes the stable phases at mantle pressures for a wide range of temperatures by system Gibbs free energy
minimization. Through the same equations of state that model the Gibbs free energy, we compute elastic moduli
and density
for each stable phase assemblage at the same P-T conditions.
One straightforward application of this approach is the study of the seismic signature of synthetic mantle
discontinuities
arising in such models, as the temperature dependent phase transformations occuring at around 410 Km and
660 Km depth
are naturally taken into account. We study these a priori known discontinuities by analysing the synthetic global
seismic data obtained from full 3D global wave propagation through our geodynamically derived models using
the spectral element method (SPECFEM3D, Komatitsch and Tromp 2002a,b). Classical techniques from global
seismology as for example SS precursors or receiver functions are possible candidates for this task.
UR: http://www.bernhard-schuberth.de
DE: 0545 Modeling (4255)
DE: 3909 Elasticity and anelasticity
DE: 7203 Body waves
DE: 7208 Mantle (1212, 1213, 8124)
DE: 7290 Computational seismology
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting