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New challenges in mapping seismic waveforms into the Earth's mantle: anisotropy and mantle flow

English title New challenges in mapping seismic waveforms into the Earth's mantle: anisotropy and mantle flow
Applicant Giardini Domenico
Number 149121
Funding scheme Project funding
Research institution Institut für Geophysik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geophysics
Start/End 01.11.2013 - 31.10.2015
Approved amount 133'426.00
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Keywords (5)

geodynamics; Earth structure; numerical methods; anisotropy; tomography

Lay Summary (German)

Lead
Unser Ziel ist es, die Struktur und Dynamik des tiefen Erdinneren besser zu verstehen. Unsere Methoden aehneln hierbei denen der medizinischen Tomographie, wobei wir jedoch die Wellen benuetzen, die von Erdbeben ausgehend das gesamte Erdinnere durchleuchten und somit weltweit an der Oberflaeche aufgenommen werden. Durch diesen sehr rechenintensiven Prozess der Tomographie entwickeln wir dreidimensionale Modelle des Erdinneren.
Lay summary
Diese Erdmodelle gelten dann als wichtige Eckpfeiler um die Dynamik der Erde zu entziffern, inklusive Entstehungsgeschichte der Erde, Waerme- und Energie Austausch zwischen Erdkern und Erdoberflaeche, und die Urspruenge von vulkanischer Aktivitaet. Der Fokus unseres Projekts liegt in der sogenannten Anisotropie. Diese Eigenschaft von Erdmaterialien laesst seismische Wellen mit verschiedener GEschwindigkeit in verschiedene Raumrichtungen ausbreiten. Wir erstellen nun Erdmodelle, die diese Richtungsabhaengigkeit explizit beinhalten. Dies laesst direkte Rueckschluesse auf die Dynamik zu, da die Richtungsabhaengigkeit zum Beispiel durch geschichtete REgionen hervorgerufen werden kann durch Druck oder Temperaturunterschiede. Dafuer haben wir einen weltweiten seismischen Datensatz gesammelt und ein erstes Model namens "SAVANI" bereits zur Veroeffentlichung abgeschickt. Der Fokus der naechsten zwei Jahre dieser Doktorarbeit von Ludwig Auer liegt darin, lokal dieses Modell zu verfeinern (wie zum Beispiel unter Europa), sowohl mit besseren Datensaetzen als auch besseren Methoden, die numerisch den Wellencharakter hervorheben, wohingegen die traditionelle Methode auf Strahlentheorie basierte.
Direct link to Lay Summary Last update: 06.11.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
AxiSEM: Broadband 3D seismic wavefields in axisymmetric media
Nissen-Meyer T. van Driel M. Stähler S. Hosseini K. Hempel S. Auer L. Colombi A. and A (2014), AxiSEM: Broadband 3D seismic wavefields in axisymmetric media, in Solid Earth Discuss., 5, 425-445.
Mantle dynamics in the Mediterranean
Faccenna C. Becker T. W. Auer L. Billi A. Boschi L. Brun J.-P. Capitanio F. A. Funicie (2014), Mantle dynamics in the Mediterranean, in Rev. Geophys., 52(3), 283-332.
Savani: a variable-resolution whole-mantle model of anisotropic shear-velocity variations based on multiple datasets
Auer L. Boschi L. Becker T. W. Nissen-Meyer T. and Giardini D. (2014), Savani: a variable-resolution whole-mantle model of anisotropic shear-velocity variations based on multiple datasets, in J. Geophys. Res., 119(4), 3006-3034.
Hydration of marginal basins and compositional variations within the continental lithospheric mantle inferred from a new global model of shear and compressional velocity
Tesoniero A. Auer L. Boschi L. and Cammarano F., Hydration of marginal basins and compositional variations within the continental lithospheric mantle inferred from a new global model of shear and compressional velocity, in J. Geophys. Res..
Thermal structure, radial anisotropy, and dynamics of oceanic boundary layers
Auer L. Becker T. W. Boschi L. and Schmerr N., Thermal structure, radial anisotropy, and dynamics of oceanic boundary layers, in Geophys. Res. Lett..

Collaboration

Group / person Country
Types of collaboration
Université Pierre et Marie Curie France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Ludwig-Maximilians-University Munich Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
University of Southern California United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
AOGS 11th Annual Meeting (2014) Talk given at a conference Enabling Broadband Waveform Modeling and Tomography for the Deep Mantle 28.07.2014 Sapporo, Japan Nissen-Meyer Tarje; Auer Ludwig;
EGU General Assembly (2014) Poster SAVANI2: towards a waveform based image of radial shear-velocity variations underneath Europe, embedded in a global model 27.04.2014 Wien, Austria Giardini Domenico; Nissen-Meyer Tarje; Auer Ludwig;
EGU General Assembly (2014) Poster Seismic Wave Propagation in Fully Anisotropic Axisymmetric Media: Applications and Practical Considerations 27.04.2014 Wien, Austria Auer Ludwig; Nissen-Meyer Tarje;


Associated projects

Number Title Start Funding scheme
134718 New challenges in seismic mapping of the Earth's mantle: anisotropy, temperature, composition 01.11.2011 Project funding

Abstract

We propose to extend the duration of our SNF grant 200021-134718, which has allowed initial train- ing of one graduate student (Mr. L. Auer-student A) at developing models of the anisotropy het- erogeneity of the Earths mantle on the basis of seismic data and constraints from geodynamics and mineral physics. We additionally request funding for a second graduate student (Mr. M. van Driel- student B), whom we hired on independent EU funds (expiring in 2013) to carry out tasks that were part of our original SNF grant (which was only partially funded). To take advantage of the success of this project over its first two years, as well as the excellent synergistic effects to be gained from the active collaboration between the two students, we propose that SNF funds both Mr. Auer and Mr. van Driel for two additional years.Our work consists of converting diverse, comprehensive and growing databases of seismic obser- vations into three-dimensional models of anisotropic seismic wavespeeds in the mantle, and of inter- preting those in terms of convective flow and/or compositional heterogeneity. Student A has focused on the tomographic inversion of seismic data, and on the quantitative interpretation of tomography in connection with mantle dynamics. Student B has worked on the development of original software to quantify the sensitivity of seismic data to anisotropic structure using full-wavefield modelling. The software developed by student B must now be joined with the tomography tools developed by student A. An important deliverable of our project will be a new 3-D model of shear velocity and its anisotropy throughout the mantle. Model resolution will be particularly high under the eastern Mediterranean, where proprietary data from a very recent, high-density broadband seismic network are now available to us. Both locally and globally, our adaptive-resolution tomography model will be based on a wider database, and more advanced forward and inverse theory than any of its predecessors.In addition to deriving and interpreting new models of Earth’s interior, we shall embark on vali- dating our results by means of posteriori wavefield modelling, thus estimating potential uncertainties, shortcomings, and robustness with respect to satisfying the data. This will be achieved by a novel technique based on scattering approaches that is currently developed by student B.After using seismic tomography to identify anisotropic, three-dimensional models of the entire mantle, we will apply results from mineral physics to interpret those anisotropy variations in terms of lattice-, crystallographic-, or shape-preferred orientation. Once this step is taken, it will be possible to draw a connection between seismic constraints and geodynamic predictions, verify whether our new models explain surface observables like gravity, topography, and plate motions, and whether our maps of anisotropy are in agreement with the modeled pattern of convective flow. Combining our thereby gained competence in tomographic imaging, experimental mineral physics and dynamic modeling will allow us to simultaneously tune seismic images and flow models, progressively identifying a single, integrated model of the Earths mantle.
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