Hrvoje Tkal¿i¿ is professor and head of Geophysics at the Australian National University, where he is director of the Warramunga Seismic and Infrasound Monitoring Facility. Recipient of the Price Medal of the Royal Astronomical Society, he is a fellow of the Australian Academy of Science and the American Geophysical Union, recognized for his fundamental contributions to the study of Earth’s interior. His books include The Earth’s Inner Core.