Stromboli video clips
Visual, seismic and pressure activity of an explosion
This movie (QuickTime, 1.1Mb) is part of the Laurea Thesis of Dr. Massimo Della Schiava and shows the correlation between visual, seismic and pressure activity of an explosion (date 08/13/1994, local time 20:58:31) at the NE crater of Stromboli volcano,The images were taken with a video camera (Hitachi, VM-S7200E), digitized and synchronized with seismic and infrasonic signals recorded by the seismic network of the Department of Earth Sciences of the University of Florence (coordinated by Dr. Maurizio Ripepe).
The upper trace is from a short period seismometer (Mark L4), the lower one from a pressure sensor, both located in the Fossa, 150m from the crater. The vertical ticks are 5 seconds apart.
The seismic trace is characterized by a low frequency signal (1-3 Hz) followed by a high frequency signal (5-10 Hz). During the low frequency event there is not yet any visual activity and no signal on the pressure sensor. The first onset of the infrasonic wave is correlated with the beginning of the explosion at the crater and with the high frequency signal. In this case there is a 4.5 seconds of delay between the first seismic signal and the explosion.