Veliko nam je zadovoljstvo pozvati vas na predavanje koje će u ponedjeljak, 17. lipnja 2024., s početkom u 12:15, održati prof. dr. sc. Hrvoje Tkalčić s Research School of Earth Sciences, The Australian National University. Sažetak predavanja i životopis su na dnu maila.
Tema predavanja je “The Earth’s inner core: a planet within the planet”. Predavanje će se održati u amfiteatru A1-1 na Prirodoslovno-matematičkom fakultetu u Splitu (R. Boškovića 33), a bit će ga moguće pratiti i on-line putem poveznice:
Sažetak predavanja kao i kratki životopis predavača u nastavku.
Sažetak predavanja:
Despite considerable progress in global seismology, mineral physics, geodynamics, paleomagnetism, computational methods and mathematical geophysics, Earth’s inner core remains enigmatic. Indeed, progress in understanding the structure and evolution of the Earth’s inner core – a metallic ball about the size of Pluto – has been impeded by the lack of geometric coverage of seismic body waves due to an uneven global distribution of earthquakes and receivers. For example, only recently have we confirmed that its innermost part contains distinct seismic anisotropy. In seeking ways forward, we started experimenting with earthquake coda correlation by comparing digital waveforms recorded at different locations many hours after the onset of large earthquakes.
Applying the coda correlation principles proved the inner core’s solidity by unambiguously detecting shear waves spreading through it. We also showed that a single seismograph and global-scale waveform cross-correlations between seismic events (inter-source correlation) could be used to scan planetary cores. Recent advances in tomography led us to the first images of the thermal convection cell at the top of the inner core. Using a growing number of global seismic stations, we observed up-to-fivefold reverberating waves from selected earthquakes along the Earth’s diameter, confirming the existence of the innermost inner core. I will review my group’s most important results and ambitions to date, with brief stops at the Earth’s centre and its various shells, the Outback, the Southern Ocean bottom, Antarctica and Mars. As I hope to demonstrate, the coda-correlation and similar innovative methods – apart from further development and the proliferation of seismic sensors – may play a central role in global and planetary seismology in the coming decades.  
Hrvoje Tkalčić is a professor and Head of Geophysics at the RSES, the Australian National University. He graduated from the University of Zagreb with the Diploma of Engineering in Physics degree, specialising in geophysics with meteorology. He gained his PhD in geophysics from UC Berkeley in 2001. He was a postdoctoral fellow at SCRIPPS/UCSD and Lawrence Livermore National Lab. His research interests include the structure and dynamics of the Earth’s interior using observational seismology and mathematical geophysics, from the crust to the Earth’s centre. Professor Tkalčić is a Director of the Warramunga Seismic and Infrasound Array in the Northern Territory, Australia, operated on behalf of the UN CTBTO and the Australian Government. He participates in improving global coverage of seismic data by deployment in remote regions of the Earth, including oceans. He has authored over 115 peer-reviewed research papers and the first book on the Earth’s inner core, published by the Cambridge University Press in 2017. He received an inaugural award from AuScope for Excellence in Research in 2016 and the Price Medal from the Royal Astronomical Society in London in 2022. He has been a Fellow of the American Geophysical Union since 2020 and a Fellow of the Australian Academy of Science since this year.

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