Today's Menu: Global Seismic Tomography...
Prepared by
Harmen Bijwaard
Appetizer
Welcome to this website. You have come to the
right place for
a magical tour through the colourful world of global seismic
tomography.
In short: seismic tomography is a technique
to image the interior of the Earth with (pressure) waves that are generated
by earthquakes. The method is comparable to that of the CT scan that is used to image the interior of the human body.
In 1999 I completed
a PhD thesis on global seismic tomography at the
Faculty of Earth Sciences of Utrecht University
. Since 2000 I am involved in radiation research (including CT scan technology) at the
Dutch
National Institute for Public Health and the Environment (RIVM)
.
For recent publications look at my
curriculum vitae
or
my latest paper.
Apart from that, I also contribute to RIVM reports.
To illustrate seismic tomography imaging,
you can click the above image to start an animation of a part of my
3D global tomography model. It depicts an isosurface of 0.5% higher
than average wavespeed, showing sunken (subducted) plate material below Japan,
the Izu-Bonin arc and the Kurile Islands from the Earth's surface to the core-mantle boundary
(2900 km deep). Notice how the platelike structures in the upper part
are connected with a huge volume in the lower mantle through a
narrow 'chimney'. Earlier studies have hinted at the existence
of such a plate "graveyard" in the lowermost mantle of this region.
Main course
Some time ago I wrote
a Dutch introductory note about seismic tomography.
It was meant for a magazine for sophomore students
in the sciences ('de Vakidioot'), but no mathematical background is needed to understand it.
For those of you that do not read Dutch I have also made
an English version
.
For Earth scientists I have a
short description of my PhD project.
And for the real insiders: Here's a picture of my PhD advisor, Wim Spakman, proudly showing some
tomography images. This picture was taken at the European
Geophysical Society meeting in Nice in 1998 (after the wine tasting...).
Results of my PhD research have been presented at the following conferences:
- Third Dutch Earth Science Meeting, Veldhoven, The Netherlands,
2-3 May 1996.
- General Assembly of the European Geophysical Society, The Hague,
The Netherlands, 6-10 May 1996.
- Fall meeting of the American Geophysical Union, San Francisco,
USA, 15-19 December 1996.
(abstract)
- General Assembly of the International Association of Seismology
and Physics of the Earth's Interior (IASPEI), Thessaloniki, Greece,
18-28 August 1997.
(invited abstract)
- Shalheveth Freier First International Workshop on Advanced Methods
in Seismic Analysis, Dead Sea, Israel, 12-15 January 1998.
(abstract 1)
(abstract 2)
- General Assembly of the European Geophysical Society, Nice,
France, 20-25 April 1998.
(abstract)
- Fourth Dutch Earth Science Meeting, Veldhoven, The Netherlands,
7-8 May 1998.
(abstract)
(poster)
- The Vening Meinesz School of Geodynamics Symposium, Utrecht, The Netherlands,
20 November 1998.
(abstract)
(poster)
- The "Superplume" workshop, Wako, Japan, 28-31 January 1999.
(invited abstract)
(poster)
- General Assembly of the European Geophysical Society, The Hague,
The Netherlands, 19-23 April 1999.
(abstract 1)
(abstract 2)
- International Workshop on Tomographic Imaging of 3-D Velocity Structures and Accurate Earthquake Location, Platres, Cyprus, 5-9 July 1999.
(abstract 1)
(abstract 2)
- International Union of Geodesy and Geophysics (IUGG) 99, Birmingham, United Kingdom, 18-30 July 1999.
(invited abstract)
Main scientific publications resulting from my PhD research (for a complete list
look at my
c.v.):
- Closing the gap between regional and global travel time tomography,
H. Bijwaard, W. Spakman, and E. R. Engdahl, J. Geophys. Res., 103, B12,
30,055-30,078, 1998.
(This was the most cited Dutch Earth Sciences paper according to the CWTS study published in Elsevier. For the full study click here.)
- Tomographic evidence for a narrow whole mantle plume below Iceland,
H. Bijwaard and W. Spakman, Earth Planet. Sci. Lett., 166, 121-126, 1999.
(In May 2001 this paper ranked 23rd in the FOM top 40 of hot papers in physics)
- Fast kinematic ray tracing of first- and later-arriving global seismic
phases, H. Bijwaard and W. Spakman, Geophys. J. Int., 139, 359-369, 1999.
- Nonlinear global P-wave tomography by iterated linearized inversion,
H. Bijwaard and W. Spakman, Geophys. J. Int., 141, 71-82, 2000.
- Mesozoic subducted slabs under Siberia, R. van der Voo, W. Spakman, and
H. Bijwaard, Nature, 397, 246-249, 1999.
- Tethyan subducted slabs under India, R. van der Voo, W. Spakman, and
H. Bijwaard, Earth Planet. Sci. Lett., 171, 7-20, 1999.
- A lower mantle source for central European volcanism, S. Goes, W.
Spakman, and H. Bijwaard, Science, 286, 1928-1931, 1999.
Related (non-scientific) publications in (mostly Dutch)
newspapers/magazines:
- Aardkorst kan zeer diepe duik maken, B. Scholtens, de Volkskrant, April 12, 1997.
- Onze resolutie is echt uniek in de wereld; Aardwetenschappers brengen bovenste 3000 kilometer van de aarde in kaart, F. van Mieghem, Utrechts Universiteitsblad, March 5, 1998.
- Sunken Chunk of Earth's History Located, S. Pobojewski, UniScience News, January 21, 1999.
- Zeebodem onder Bajkal-meer, de Volkskrant, January 23, 1999.
- Verloren continent gevonden, Intermediair, February 11, 1999.
- Het oor aan de aarde, B. Scholtens, de Volkskrant, February 27, 1999.
- Iceland's Fires Tap the Heart of the Planet, R.A. Kerr, Science, May 14, 1999.
- Buitenlanders scoren voor Utrecht, U-blad, June 6, 2001.
- Toppers met stip, de meest recente hot papers, Elsevier, March 16, 2002.
For Earth Sciences links I can recommend the
tectonophysics page.
This page has also been included in the Science Lab.
Acknowledgements:
The investigations have been supported by the Netherlands Geoscience Foundation
(GOA) with financial aid from the Netherlands Organization for Scientific
Research (NWO).
Dessert
You are by now probably wondering whether you have this
website all to
yourself. Well, a number of people have been here before you, but there
are still many more that haven't ....
Note that the number of website visits is no longer updated.
Harmen Bijwaard
e-mail:harmen.bijwaard[AT]rivm.nl
This page was last updated September 1, 2008.