@article {13655, title = {Seismic Observations with broadband instruments at Thira Volcano (Greece)}, journal = {Bulletin of the Geological Society of Greece}, volume = {XXXX}, year = {2007}, pages = {1250-1261}, abstract = {Two arrays equipped with broadband sensors were installed for a period of 10 months, in order to study the seismic activity in the area of Santorini (Thira) volcano. During these periods, about 330 earthquakes were recorded and located within a radius of 50 km from the center of the caldera. An iterative damped traveltime inversion procedure yielded a local 1-D\ Ρ-wave velocity model and improved locations with an accuracy better than 5 Km in both horizontal and vertical components for 135 earthquakes. Those are mainly distributed within a depth range 5-18 Km, in the vicinity of the submarine Kolumbo Reef (NE of Santorini Island). Signal analysis of the recorded volcanic earthquakes including typical Fourier transformations and several operations in the time-frequency domain, allowed their dominant frequency determination and their classification into three groups based on waveform appearance and frequency content: (1) highfrequency events; (2) low-frequency events; and (3) volcanic tremor. Frequencytime analysis of tremor, detected at three stations, revealed two kinds of harmonic tremor with one sharp peak, at 3-5 Hz and 8.5-10 Hz.}, url = {https://ejournals.epublishing.ekt.gr/index.php/geosociety/article/view/16844}, author = {A. Kolaitis and Papadimitriou, P. and Kassaras, I. and Makropoulos, K.} }