Seismology

People in the seismology group

Faculty

Jeannot Trampert
Arwen Deuss
Hanneke Paulssen
Elmer Ruigrok
Ivan Vasconcelos

Electronics Engineer

Arie van Wettum


ICT Manager

Theo van Zessen


Group Secretary

Ildikó Csikós
Postdocs

Laura Cobden
Andreas Fichtner
Neslihan Ozmen-Eryilmaz



PhD students

Fatemeh Akbarashrafi
Suzanne Atkins
Nienke Blom
Evangelos Korkolis
Maria Koroni
Agnieszka Plonka
Simon Schneider
Sujania Talavera Soza
Wen Zhou
MSc students

Xiuying Chen
Rhys Coles
Yael Engbers
Dirk van Haeringen
Lisanne Jagt
Darrell Tang
Annisa Rachmi Trahwiwit
Madelon Smink
Caron Vossen


Alumni


PhDs and Postdocs

Jeannot Trampert

Research Interests

* Full waveform inversion and inverse theory in general

* Seismic tomography (uncertainty analysis and thermo-chemical interpretation)

  with special focus on anisotropy and density imaging

* (Numerical) wave propagation in complex media

* Advanced processing of seismic data using pattern recognition techniques

* Seismic interferometry


website: http://www.geo.uu.nl/~jeannot

e-mail: J.A.Trampert@uu.nl

phone: +31 (0)30 253 5088



Hanneke Paulssen


Research interests:

* Regional surface wave seismology
* Induced seismicity
* Deep Earth (inner core, D")

Coordination NARS network.



website: http://www.uu.nl/staff/JAMPaulssen/0

e-mail: h.paulssen@uu.nl

phone: +31 (0)30 253 5089



Arwen Deuss

Research interests:

* Normal mode based tomography
* Seismic imaging of the Earth's core
* Observation of mantle discontinuities
* Interpretation of seismology in terms of mineral physics and fluid dynamics




website: http://www.geo.uu.nl/~deuss

e-mail: A.F.Deuss@uu.nl

phone: +31 (0)30 253 5136



Ivan Vasconcelos

Research interests:

* Imaging science, inverse problems, compressive sensing applications
* Acoustic, elastic and electro-magnetic wave propagation
* Exploration seismology: nonlinear waveform imaging & monitoring (passive and active),
  image-driven acquisition design, wavefield gradiometry in acquisition and imaging
* Global seismology: seismic interferometry & redatuming, large-array imaging with
  exploration methods, elastic multiple scattering
* Radar imaging for near-surface, cryosphere and planetary science: acquisition design,
  EM gradiometry, nonlinear redatuming & imaging
* Material science for geophysics: describing micro-structure properties, effective properties
  and wave propagation at finite-frequencies




phone: +31 (0)30 253 5137

e-mail: I.Vasconcelos@uu.nl


Arie van Wettum


My main responsibility is the deployment of our seismological equipment in the different NARS projects. It involves the design and upgrade of the necessary hard and software as well as the field installation, maintenance and data processing. Programming skills are C, Assembly, Fortran, HTML, CSS and Basic, used at different platforms. Main interests are system developments to reduce space, energy and cost while reliability and quality increase.




e-mail: A.vanWettum@uu.nl

phone: +31 (0)30 253 5159



Theo van Zessen


I am responsible for all the computing facilities of the geophysics group. This implies

- Designing and maintaining High performance computing (HPC) clusters that are used

  for modeling and analyzing seismic data.

- Providing software tools for the scientific staff.

- Taking care of the storage, backup and archiving of the their data.

Furthermore, I install, configure, maintain and support the server and desktop systems for our staff and students.


e-mail: t.vanzessen@uu.nl

phone: +31 (0)30 253 5185




Ildikó Csikós



Secretary Department of Earth Sciences – Earth Sciences Office


My function is providing secretarial and management support for the Earth Sciences Office and Research groups.


website: http://www.uu.nl/staff/ICsikos/0

e-mail: I.Csikos@uu.nl

phone: +31 (0)30 253 5151



Fatemeh Akbarashrafi


An unbiased estimation of the 3-D density field is essential to separate thermal from compositional structures in the mantle. While geodynamic observables provide some information, long period seismic data are most suitable. Any waveform inversion technique needs the capability to calculate synthetic seismograms in a 3-D earth model. We propose to develop a code to calculate exact seismograms in a 3-D Earth using full mode coupling theory. This code will then be used together with a fast Monte Carlo technique to derive probability density functions of 3-D density models and elastic parameters. This work is part of the ERC project iGEO which aims to combine geophysical and geochemical observation to constrain the nature of convection inside the Earth.


e-mail: F.Akbarashrafi@uu.nl

phone: +31 (0)30 253 5087



Suzanne Atkins


Properties of the mantle, such as composition, temperature and viscosity have a major effect on the evolution of mantle flow patterns. These properties also determine density and elasticity, which in turn cause variations in seismic wave speeds. However, at present, these parameters are poorly known, limiting the development of geodynamical mantle flow models, and the interpretation of velocity variations in the mantle. My project aims to provide new estimates for these parameters by training artificial neural networks to recognise the initial input parameters used in mantle flow models from the synthetic seismograms produced from these flow models. Once the network has been trained, it will hopefully be able to recognise the initial input parameter that would start a model identical to the Earth by using observed seismograms.


e-mail: S.E.Atkins@uu.nl

phone: +31 (0)30 253 5138



Nienke Blom


I work on density tomography, a PhD project that started in October 2013. Density drives convection in the Earth on all scales, and in the mantle acts as an important discriminator between thermal and compositional heterogeneities. Yet, the density structure in the Earth remains largely unknown. The goal of this project is to explore the ability of Waveform Inversion to constrain 3D density variations on regional to global scales. More specifically, I work on the incorporation of additional types of information (such as gravity and mineral physics data) along with the seismic waveforms, and the efficient use of hard constraints. This is done in collaboration with Andreas Fichtner (UU, ETH Zürich).
Previously, I have worked with Arwen Deuss on inner core seismic structure.


website: http://www.geo.uu.nl/~blom

e-mail: N.A.Blom@uu.nl

phone: +31 (0)30 253 5087



Evangelos Korkolis


I am developing an acoustic emission monitoring and ultrasound imaging system for the rotary shear apparatus at the High Pressure and Temperature (HPT) laboratory at Utrecht University. This system can detect transient phenomena that occur during sliding experiments that simulate fault slip at earthquake nucleation velocities. Analysis of such transients will hopefully further our understanding of the microphysical basis of rate and state friction laws. My work is part of André Niemeijer's SEISMIC project, funded by the European Research Council.



website: http://www.uu.nl/staff/Ekorkolis

e-mail: E.Korkolis@uu.nl

phone: +31 (0)30 253 4965



Laura Cobden


I love to learn about the dynamics and composition of the deep Earth, especially in the lower mantle. Seismology is our most powerful tool for acquiring in-situ observations of the Earth's interior, but in order to convert from seismic to physical structure, we need to understand the relationship between seismic observables and thermodynamic parameters. This is a non-trivial task, and in my research I collaborate with seismologists, geodynamicists, statisticians and mineral physicists to try to understand and quantify what constraints seismic data allow us to place on the thermal and chemical properties of the deep Earth. In recent years I have worked mainly on the core-mantle boundary region and in future I plan to focus also on the mantle transition zone.


website: http://www.geo.uu.nl/~laura

e-mail: L.J.Cobden@uu.nl

phone: +31 (0)30 253 5085



Andreas Fichtner


My research is centered around the development and the application of numerical wave propagation methods to seismic tomography. Specifically I am working on a full waveform inversion of the European upper mantle, probabilitic waveform tomography and the sampling problem in high-dimensional model spaces.




website: http://www.geo.uu.nl/~fichtner

e-mail: A.Fichtner@uu.nl

phone: +31 (0)30 253 5948



Maria Koroni


Much is known about the physical processes of solid-state convection in the Earth's mantle, but the parameters that enter their mathematical description are not very well established. Once these parameters are determined, the thermo-chemical evolution of our planet can self-consistently be modelled. The state-of-the-art is to roughly estimate these parameters and qualitatively compare the modelling to some relevant geophysical, geochemical or geological observations. This comparison is not comprehensive and never explains all observables. To constrain geodynamic models, it is essential to image the 3D variations of density in the mantle and to map the topography of mantle discontinuities, especially at 660 km depth and at the core-mantle boundary. In this project, we propose to use full waveform adjoint tomography for imaging. We will seek to define optimal measurements which enhance the recovery of discontinuities and density. To map the discontinuities, we will use an existing spectral element code. For the recovery of density, we will need to develop a full-coupling normal mode code which treats gravity exactly.


e-mail: M.Koroni@uu.nl

phone: +31 (0)30 253 5138



Neslihan Ozmen-Eryilmaz


My main research interests are the computation of acoustic wave field propagation, and efficient solution of the nonlinear inverse scattering problems for advanced imaging. Though in the past I\u2019ve worked in medical applications, in this project we will focus on developing new seismic imaging techniques, capable of monitoring fluids flowing in the subsurface. The potential to image fluid bulk modulus and density has been demonstrated using full waveform inversion in poro-elastic media, but robust imaging is still highly problematic. I use poro-elastic wave propagation code in combination with multi-phase flow calculations to produce synthetic seismic data. I also investigate techniques for adapting adjoint full waveform tomography to fluids, and for applying new data-driven methods to create virtual sources inside an unknown medium.


e-mail: N.Ozmen@uu.nl

phone: +31 (0)30 253 5085



Agnieszka Plonka


Lateral density variations are the source of mass transport in the Earth on all scales - and particularly, they are driving the convective motion in the mantle. They are also essential to discriminate between compositional and thermal heterogeneities. However, classic seismic observables and gravity provide only weak constraints with strong trade-offs, and so the density structure of the Earth remains largely unknown. My goal is to understand the effect of 3D density heterogeneities on seismic data. I study those effects systematically using numerical wave propagation in order to design measurements which are sensitive to density and nearly insensitive to other Earth model parameters.


e-mail: A.I.Plonka@uu.nl

phone: +31 (0)30 253 5087



Simon Schneider


I am also part of the 2016 ERC project ATUNE, where I will work with Earth’s free oscillations or normal modes. The goal of this project is to develop a new set of methods to measure Earth’s elastic and anelastic parameters and perform a fully coupled direct spectrum inversion for both velocity and attenuation structure, generating a comprehensive model of Earth’s mantle from crust to core. In this project I will examine the importance of toroidal modes and spheroidal-toroidal mode coupling on elastic and anelastic parameters, using splitting function measurements.


e-mail: S.A.Schneider@uu.nl

phone: +31 (0)30 253 5138



Sujania Talavera Soza


Robust estimates of the Earth’s temperature, composition and partial melt are hard to obtain from seismic tomography models based only on wave velocities. Seismic attenuation, or loss of the waves’ energy, will add crucial information and allow us to answer elemental questions regarding the existence of water and melt within the mantle. For the first time, the ERC project ATUNE will use long-period free oscillations or normal modes to model 3D attenuation variations in the mantle. Within this project I will measure elastic and anelastic splitting functions, which are depth-averaged models of how one particular mode ‘sees’ the Earth. In particular, anelastic splitting functions have not systematically been measured before for mantle sensitive modes.


e-mail: S.A.TalaveraSoza@uu.nl

phone: +31 (0)30 253 5087



Elmer Ruigrok


Wavefields induced by earthquakes are highly complicated, both due to refined source characteristics and complex structure. As a consequence, the resulting vibrations, recorded at the Earth's surface, are hard to fully understand. Yet, it are the complicated arrivals that are key to further unravelling Earth's structure and its dynamics. I work on array methods to turn complicated seismic measurements into interpretable data. In the past, I focused on methods that use the data for unveiling Earth structure. Currently, I focus on obtaining source characteristics, especially from induced seismicity.



e-mail: E.N.Ruigrok@uu.nl

phone: +31 (0)30 253 5085




Wen Zhou


I will investigate the effects of fault rheology on microseismic signatures. My research in the laboratory will concentrate on the factors that control the evolution of slip and slip velocity at the nucleation stage of slip as characterized by the recorded seismic signals. The laboratory results will be compared to records of microseismic activity from oil, gas, or geothermal fields to further investigate the relationship between fault rock properties and the nature of the seismic signal.


e-mail: w.zhou@uu.nl

phone: +31 (0)30 253 2103



PhD and Postdoc alumni
Dolors Alsina 1996 Jay Pulliam 1996
Caroline Beghein 2003 Joe Resovsky 2003
Ebru Bozdag 2009 Florian Rickers 2013
Andrew Curtis 1997 Axel Röhm 1999
Frédéric Deschamps 2005 Martin Schimmel 1997
Harm Dorren 1995 Anne Sieminski 2008
Stéphanie Godey 2002 Jesper Spetzler 2001
Sonja Greve 2012 Benoît Tauzin 2010
Renate Hartog 2002 Andrew Valentine 2016
Paul Käufl 2015 Karin Visser 2008
Wouter Kimman 2011 Denise de Vos 2016
Dirk Kraaijpoel 2003 Robbert van Vossen 2007
Sergei Lebedev 2008 Ralph de Wit 2015
Anthony Lomax 1997 Tedi Yudistira 2015
Alison Malcolm 2007 Xiaomei Zhang 2009
Ueli Meier 2008
Ilaria Mosca 2010
Everhard Muyzert 1998
Filip Neele 1995
Tijn Passier 1996
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