A/Prof Hrvoje Tkalčić
Senior Fellow, Seismology and Mathematical Geophysics/Earth Physics
Research School
of Earth Sciences,
The Australian
National University
Canberra, ACT 0200, AUSTRALIA
tel: +61-2-6125 3213
fax: +61-2-6257 2737
Email: Hrvoje.Tkalcic @ anu.edu.au
With PhD students on the ANU campus, May 2013. From left: Surya Pachhai,
Tanja Pejić, Mallory Young and Marija Mustać.
THE SHUFFLING ROTATION OF THE EARTH'S INNER CORE
The image above illustrates the ray-paths of elastic waves of an earthquake doublet
from the South Sandwich Islands region travelling through the Earth's inner
core to station COLA in Alaska. 7 new doublets and 17 old doublets were
analysed to reconstruct the history of inner core rotation with respect to
the mantle. This led to the discovery that the rotation rate of the inner core
with respect to the mantle is variable in time. A transdimensional Bayesian inversion
was used to interpret the travel time data. Image credit: Rhys Hawkins, National Computational
Infrastructure
Article:
by H. Tkalčić, M.K. Young, T. Bodin, S. Ngo & M. Sambridge
The shuffling rotation of the Earth's inner core revealed by earthquake doublets
Nature Geoscience, DOI:10.1038/NGEO1813, 2013.
News selection:
ANU Press Release
Canberra Times
ABC News
Our Amazing Planet
Yahoo News
NBC News
Phys.org
Discovery
Sydney Herald
Tendencias
Milenio
Emol
Xinhua
Sterne-und-Weltraum.de
Metronieuws.nl
Youtube
Mk.ru
Gaianews.it
Journal-dela-science.fr
Journal-de-noticias.pr
ABC Science "StarStuff" talk show with Stuart Gary
"Science News" on Croatian National Television HTV1
"On Science" talk show on Croatian National Radio HR1
Thomas Bodin's interview for German Public Radio/SWR
Publications
Curriculum Vitae
News and media 
Opportunities for students
PHYS3070 Course material
Research Interests
The Australian Outback through my lens
A look inside a volcano: Le Piton de la Fournaise, La Reunion Island
Free Software
IRFFM (Interactive Receiver Functions Forward Modeller)
v1.1
RESEARCH HIGHLIGHTS
INNER CORE SAMPLING BY PKP WAVES VIDEO
Click on the image above to see an animation of our current spatial coverage of the inner core
by PKP waves. Uneven distribution of large earthquakes and seismic stations installed worldwide
limits this sampling. More installations are needed to help advance our understanding of the deep
Earth.
The PKP dataset and tomographic model are from Tkalčić et al.,
GJI 2002, Leykam et al., GJI 2010, and Tkalčić, GRL 2010. Green dots are station-,
while red dots are earthquake-locations. The yellow sphere is the Earth's inner core, seen through the
compressional velocity field observed for the lowermost mantle. Blue lines are fast,
and red lines are slow ray-paths through the Earth. This animation is made in collaboration with NCI's Rhys Hawkins.
Source: "The Earth's inner core - exposed by observational seismology", H. Tkalčić, in preparation
Watch another video of inner core sampling (without lowermost mantle structure) on youtube
INNER CORE AS A CONGLOMERATE OF ANISOTROPIC DOMAINS 
Click on the image above to find out more about recent research on
the inner core.
BENFORD'S LAW IN GEOSCIENCES
More about this topic under
News and media.
For more information, see research pages of
Malcolm Sambridge.
VOLCANIC EARTHQUAKES IN ICELAND WITH ANOMALOUS SEISMIC
RADIATION 
Click on the image above to find out more about recent research on
anomalous earthquakes in Iceland.
SMALL-SCALE HETEROGENEITY OR PARTIAL
MELT IN THE UPPER MANTLE POSTULATED FROM FIRST OBSERVATIONS AND MODELING
OF "PODAL" PKPPKP WAVES AND THEIR PRECURSORS
Click on the MPEG icon to watch a movie
showing PKPPKP main phase at lower frequencies, and prominent PKPPKP
precursors at higher frequencies, for an Alaskan earthquake observed at
the ILAR array. These precursors are interpreted as reflections from the
upper mantle heterogeneity between 150 and 220 km depth.
Click on
the image above to find out more about the first observations of "podal"
PKPPKP waves and their precursors.
LARGE POLARIZATION ANISOTROPY IN THE
MANTLE OBSERVED THROUGH MULTI-STEP MODELING OF RECEIVER FUNCTIONS AND SURFACE
WAVES
Click on the image above to find out more
about multi-step modeling of receiver functions and surface wave dispersion, and
the observation of large polarization anisotropy in the upper mantle.
COMPRESSIONAL VELOCITY MODEL OF THE LOWERMOST
MANTLE
Click on the
image above for more details on P wave tomography of the Earth's lowermost mantle using PKP
and PcP waves and implications for anisotropy in the inner core. You are welcome to
download TRH_KC model with plotting instructions and figures.
