Dana 21.02.2018. u 14:15 h održat će se na Geofizičkom odsjeku PMF-a sljedeće izlaganje:
Dr Petr Kolínský
(Department of Meteorology and Geophysics, Faculty of Earth Sciences, Geography and
Astronomy, University of Vienna)
Surface wave propagation across AlpArray
Pozivaju se studenti i svi zainteresirani da prisustvuju predavanju, koje će se održati u predavaoni P2 Geofizičkog odsjeka PMF-a, Horvatovac 95, Zagreb.
Records of 30 teleseismic and regional earthquakes from the two first years of the AlpArray project are studied. Fundamental modes of surface waves in the range of 20 - 160 seconds are extracted. An array technique which allows for simultaneous determination of phase velocities and true backazimuths of propagation is introduced and used for more then 500 stations across Europe. Wavefronts from single-station measurement are estimated to benchmark the results from the array measurement. Significant off-great circle deviations are found and discussed. For waves propagating from specific regions, striking wavefront distortion is observed. It is explained by diffraction at small-scale heterogeneities. By modeling the effects of the heterogeneities on the wavefield, we are able to detect and locate the respective anomalies even being thousand of kilometers far both from the earthquakes as well as from the stations. Approximate size of the heterogeneity as well as the velocity anomaly can be estimated.