VOLCANOLOGY


The Laboratory of Experimental Geophysics is equipped to carry out research and teaching in the field of Geophysics devoted to the study of the dynamics of explosive, mostly strombolian type, active volcanoes.

Since 1987, the Laboratory is active, with permanent headquarters office at the traffic light at Old San Vincenzo Stromboli for research and monitoring of the volcano Stromboli, which is in fact a perfect natural laboratory for the study of the dynamics of explosive volcanic, as it is characterized by a persistent and regular activities. The multiparametric approach to the study and monitoring of the processes that occur in volcanic systems proved to be crucial for a better understanding and interpretation of the dynamics at work and the definition of the possible risk scenarios related.

The results of the calculations are interpreted according to an explosive dynamic model that is based on the latest research results in the field of Strombolian explosive dynamics , which makes them a very useful tool in the surveillance for the purposes of Civil Protection. According to the currently accepted model ( Kazahaya et al., 1994 and Stevenson and Blake, 1998), the magma rich in gas, salt to density difference, Degas and descends along the walls of the magma conduit with continuous cycles. An increase of the amount of gas in the system causes a decrease of the average density and a local increase of the effective viscosity, so to create the conditions suitable to trap gas bubbles. When a gas bubble in overpressure goes back inside the magma conduit, it expands and the change in volume generates a seismic signal in the long period VLP. The amplitude of this signal is proportional to the volume of gas in expansion. After reaching the surface magma - air, the pressure difference between the internal pressure of the bubble and the external one, triggers the explosion generating a pressure wave. The greater the internal overpressure, the greater the variation of the pressure generated and then that of the infrasonic signal is recorded to the acoustic sensors. In proportion with the internal overpressure, the gas and the lava fragments date back to the surface with greater or lesser velocity of the gas. This speed variation is the cause of a greater or lesser time delay between the signal infrasonic and thermal linked to the escape of gas and lava fragments. All explosions are accompanied by signs of deformational inflation and deflation, indices of a system that collects and releases.

 

 

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