for Seismic Wave Propagation on Regional and Global Scales Gunnar Jahnke Department of Earth and Environmental Sciences,

Last update: 22. June 2013
Numerical Methods for Seismic Wave Propagation on Regional and Global Scales Link to thesis Regional modelling: Simulation of regional 3D models is done for fault zones, especially to investigate so calledTrapped Waves which are very sensible on fault structure at depth (for example seismograms see here). The detailed structure of a fault zone (FZ) plays an important role in problems related to fault mechanics, dynamic rupture, wave propagation and seismic hazard. FZs are thought to consist of a O(10100)m wide region of decreased seismic velocity. The small spatial scales involved make such structures difficult to image with raytheoretical methods (tomography). However, when seismic sources are located at or near such lowvelocity structure, energy is trapped inside the FZ leading to dispersive wave trains carrying information on the FZ structure. These waves can travel many kilometers inside the fault before reaching the surface and are therefore strongly altered by its properties. Candidate trapped waves have been observed above several active faults. Inversion algorithms exist which explain these observations in terms of planar fault zone structures. However, at present it is not clear how reliable these estimates are as the effects of (even small) 3D variations on trapped waves are not well understood. The goal of this study is to distinguish relevant and irrelevant effects on FZ waves due to 3D structure. To achieve this we perform numerical calculations of various FZ geometries and analyze the waveforms, spectra and envelopes of synthetic seismograms. The main results are that (1) moderate changes of the shape of FZ or (2) small scale heterogeneities or (3) depthdependent properties do not strongly affect the observed FZ waves. In contrast, strong effects are to be expected from (4) discontinuous FZ structure (e.g. offsets), which may at some point allow imaging such features at depth. The used method is a 3D highorder staggeredgrid finitedifference scheme. The Fault Zone modelling is done in collaboration with Prof. Heiner Igel (Geophysics Section, of the Department of Earth and Environmental Sciences, Ludwig  Maximilians Universität München) and Yehuda BenZion (Department of Earth Science, University of Southern California, Los Angeles). 
Global modelling:
The Simulations are done on high performance computers such as the Hitachi SR8000 Computer at the Leibniz Rechenzentrum München. The implementation is done with Fortran90 and MPI. 
with Tarje NissenMeyer and Markus Treml 
[11] Thorne, M. S., H. P. Crotwell, G. Jahnke, An educational resource for visualizing the global seismic wavefield, (PDF), SRL, 84 (4), 711717, 2013. [10] Thorne, M. S., Garnero, E.J., Jahnke, G., Igel, H., McNamara, A.K., Mega Ultra Low Velocity Zone and Mantle Flow (PDF), EPSL, 364, 5967, 2013. [9] Jahnke, G., Methods for Seismic Wave Propagation on Local and Global Scales with Finite Differences. (PDF), PhD Thesis, LMU München: Faculty of Geosciences, 2010. [8] Jahnke, G., M. S. Thorne, A. Cochard, H. Igel, Global SHwave propagation using a parallel axisymmetric finitedifference scheme: application to whole mantle scattering (PDF), Geophys. J. Int., 173(3): 815826, 2008. [7] Thorne, M. S., T. Lay, E. Garnero, G. Jahnke, H. Igel, 3D Seismic Imaging of the D" region beneath the Cocos Plate , Geophys. J. Int., 170, 635648, 2007. [6] Jahnke, G., H. Igel and Y. BenZion, Threedimensional calculations of fault zone guided waves in various irregular structures (Paper, Movies), Geophys. J. Int., 151, 416426, 2002. [5] Igel, H., G. Jahnke, and Y. BenZion, Numerical simulation of fault zone trapped waves: accuracy and 3D effects (PDF), Pure Appl. Geophys., 159, 20672083, 2002. [4] Fohrmann, M., H. Igel, G. Jahnke, Y. BenZion, Guided waves from sources outside faults: an indication for shallow fault zone structure? (PDF), Pure Appl. Geophys., 161, 113, 2004. [3b] Igel, H., G. Brietzke, H. Igel, G. Jahnke, M. Treml, M. Ewald, H. Wang, A Cochard, G. Wang, Computational Elastic Wave Propagation: Advances in Global and Regional Seismology (PDF), High Performance Computing in Science and Engineering, Munich 2004, Springer Verlag, pp. 447, ISBN 3540443266. [3] Igel, H., NissenMeyer, T., Jahnke, G., Wave propagation in 3D spherical sections: effects of subduction zones (PDF, HTML), Phys. Earth Planet. Int., 132, 219234, 2002. [2b] Brietzke, G., H. Igel, G. Jahnke, M. Treml, M. Ewald, H. Wang, A. Cochard and G. Wang, Computational wave propagation: advances in global and regional seismology (PDF), Report for the Leibniz Rechenzentrum (LRZ), München, 2003. [2] Igel, H., G. Brietzke, M. Ewald, M. Fohrmann, G. Jahnke, T. NissenMeyer, J. Ripperger, M. Strasser, M. Treml, and G. Wang, 3D seismic wave propagation on a global and regional scale: earthquakes, fault zones, volcanoes (PDF), High Performance Computing in Science and Engineering, Munich 2002, Springer Verlag, pp. 353, ISBN 3540004742. [1] Weber, M., Ch. W. Wicks, F. Krüger, G. Jahnke, J. Schlittenhardt, 1998, Asymmetric radiation of seismic waves from an atoll  Nuclear tests in French Polynesia (Abstract), Geophys. Res. Lett., 25, 19671970. Presentations: [16] Jahnke, G., N. Gestermann, G. Hartmann, L. Ceranna, M. Henger, Seismic Identification of the 2006 North Korean Nuclear Explosion with the IMS Network  Data Analysis and Numerical Modelling, (Abstract, Meeting of the European Geosciences Union (EGU), Apr. 2007, in Vienna (Geoph. Res. Abs, Vol. 9, 08932, 2007). [15] Jahnke G., N. Gestermann, A. Schick, L. Ceranna, M. Henger, Operation of the Earthquake Alert and Information System ALISE, (German Abstract ), Meeting of the German Geophysical Society (DGG), Mar. 2006, Bremen. [14] Jahnke G., N. Gestermann, G. Hartmann, A. Schick, L. Ceranna, M. Henger, 'ALISE'  The Alert and Information System for Earthquakes in Germany, (Abstract ), Meeting of the European Geosciences Union (EGU), Apr. 2005, in Vienna (Geoph. Res. Abs, Vol. 7, 11025, 2005). [13] Canty, M., G. Jahnke, A. Nielsen, J. Schlittenhardt, Change Detection for Remote Monitoring of Underground Nuclear Testing: Comparison with Seismic and Associated Explosion Source Phenomenological Data, (Abstract, Poster), Meeting of the European Geosciences Union (EGU), Apr. 2005, in Vienna (Geoph. Res. Abs, Vol. 7, 07208, 2005). [12] Jahnke G., N. Gestermann, G. Hartmann, A. Schick, L. Ceranna, M. Henger, 'ALISE'  The Alert and Information System for Earthquakes in Germany  First Experiences, (German Abstract, Poster), Meeting of the German Geophysical Society (DGG), Mar. 2005, in Graz. [11] Gestermann, N., G. Jahnke, G. Hartmann, A. Schick, L. Ceranna, M. Henger, An Alert and Information System for Earthquakes in Germany, (German Abstract, Photo), Meeting of the German Commitee for Disaster Reduction (DKKV), Oct. 2004, Mainz. [10] Gestermann, N., G. Jahnke, G. Hartmann, L. Ceranna, M. Henger, Development of an Earthquake Information System for Germany, (Abstract), Poster, Meeting of the European Seismological Commission (ESC), Sep. 2004, Potsdam. [9] Gestermann, N., G. Jahnke, L. Ceranna, G. Hartmann, M. Henger, Automatic Detection Routines for an Earthquake Alert System, (Abstract, Poster, in German), Meeting of the German Geophysical Society (DGG), Mar. 2004, Berlin. [8] Jahnke, G., H. Igel, High Resolution Global Wave Propagation through the whole Earth: the axisymmetric PSV and SH case (Abstract), (Poster), EGS General Assembly, Apr. 2003, Nice, France (Geoph. Res. Abs., Vol. 5, 08346, 2003). [7b] Igel H., M. Fohrmann, G. Jahnke and Y. BenZion,
Guided Waves From Sources Outside Faults: An Indication For Shallow Fault Zone Structure?
(PDF),
ACES Workshop Proceedings, 173176, May 2002, Hawaii.
[6] Jahnke, G., H.
Igel,
High frequency global wave propagation with the FD method for
axi symmetric geometries (PDF,
in German), Meeting of the German Geophysical Society (DGG), Mar. 2002,
Hannover.
[4b] Igel, H., Jahnke, G., Käser, M., BenZion, Y., Wave propagation simulation on regional scales: algorithms and applications (PDF), (Abstract), ACES Workshop Proceedings, Oct. 2000, Tokyo and Hakone, Japan. [4] Jahnke, G., Igel, H., BenZion, Y., 3D seismic wave propagation in fault zones  can trapped waves be used for a better resolution of the structure of a fault? (PDF), General Assembly of the European Seismological Commission (ESC), Sep. 2000, Lisbon, Portugal. [3] Jahnke, G., Igel, H., BenZion, Y., Three Dimensional Wave Propagation in Seismic Fault Zone Models (HTML), Meeting of the German Geophysical Society (DGG), Feb. 2000, München. [2] Jahnke, G., Igel, H., BenZion, Y., Threedimensional wave propagation in fault structures with material interfaces and depthdependent properties (PDF), AGU Fall Meeting, Dec. 1999, San Francisco. [1] Jahnke, G., M.
Weber,
Reflexionen im tiefen Erdmantel unter Neu Kaledonien (Abstract,
Poster, in German),
Meeting of the German Geophysical Society (DGG), Mar. 1998, Göttingen.
Publications using the SHaxi code: [A8] Hwang, Y. K., J. Ritsema, P. E. van Keken, S. Goes, E. Styles,
Wavefront healing renders deep plumes seismically invisible
(PDF), Geophys. J. Int. (2011) 187, 273277.
Work of the Seismology Group of the Arizona State University using the AxiSymmetric Codes: [A7] Thorne, M. S., E. J. Garnero, A. K. McNamara, G. Jahnke, H. Igel, Broadband SPdKS waveforms reveal ULVZ ridge in the central Pacific (PDF), AGU Fall Meeting, Dec. 2008, San Francisco. [A6] Thorne, M. S., S. Rost, G, Jahnke, H. Igel, Analysis of Pdiff coda using the axisymmetric finite difference method (PDF), AGU Fall Meeting, Dec. 2007, San Francisco. [A5] Thorne, M. S., Thorne, L., Garnero, E., Jahnke, G., Igel, H., 3D seismic imaging of the D'' region beneath the Cocos Plate (Abstract), (Poster.png, 1.6MB), Eos Trans. AGU, 85(47), Fall Meet. Suppl., Abstract U41A0717, 2004. [A4] Thorne, M. S., Garnero, E., Jahnke, G., Treml, M., Igel, H., Investigating the CoreMantle Boundary and ULVZ Topography with Synthetic FD Seismograms for 3D AxiSymmetric Geometries: Predictions and Data (Abstract), (Poster.png, 580kB), Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract U51B0003, 2003. [A3] Treml, M., G. Jahnke, T. NissenMeyer, H. Igel, E. Garnero, A Hybrid FiniteDifference Method for Global Wave Propagation (Abstract), DGGAnnual Meeting, Jena, Germany, 2003. [A2] Treml, M., S. Goes, G. Jahnke, T. NissenMeyer, H. Igel, Synthetic Seismic Wave Propagation through thermal Mantle Plumes (Abstract), EGSAGUEGU General Assembly, Nice, France, 2003. [A1] Schmerr,
N., Garnero, E., Igel, H., Treml, M., Jahnke, G., Probing
the nature of 410 and 660km discontinuities beneath hotspots using
the SSprecursors
(Abstract),
(Poster.png, 900kB),
Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract S21E0356, 2003.
Misc: Diplom Thesis: Analysis of weak seismic signals from small aperture arrays 
possibilities and limits Skript: Musterlösungen
zur Vorlesung Digitale Signalverarbeitung in der Seismologie I und II,
(PDF),
basierend auf der
gleichnamigen Vorlesung von Gerhard Müller, zusammengestellt von Gunnar Jahnke.
Fun Stuff: SHAxi snapshot at IRIS Image Gallery. Cover illustration: Introduction to Seismology (Textbook, P. Shearer, 2009). PSVaxiAnimation bei Focus Terra Mikes Animations of Earth and Moon quakes (SHaxi and PSVaxi)
3D Seismic Wave Propagation on a Global and Regional Scale: Earthquakes, Fault
Zones, Volcanoes
(2001)

SPICE is a European network and stands for "Seismic wave Propagation and Imaging in Complex media". It maintains a CodeLibrary of wave propagation and other algorithms. You can get some of my Finite Difference codes from the SPICE codelibray. Already included are:

Tutorial: Understanding seismic radiation patterns