Thermal-Infrared Image Analysis Application to the Real-Time Monitoring of the Explosive Activity of Etna and Stromboli Volcanoes

Starting from 1993 video-cameras were used for the monitoring of the explosive activity at Etna and Stromboli volcanoes. Using image analysis we were seeking to identify, classify and quantify the explosive events and any change of the activity trend that could precede a strong eruptive event, like paroxysmal explosion, fire fountain, lava flow. The visible-band cameras suffered of a low sensitivity that limited the early warning capability of the system at night and during poor weather. Taking into account the high-temperature of the erupted material, infrared cameras appeared the best choice to overcome this observational limitation, unfortunately at that time commercial infrared devises were still too much expensive and fragile to put in operation in such unsafe and extreme environment. In very recent time the availability of solid-state uncooled sensors made possible the use of these devices for volcano monitoring at Etna and Stromboli since their 2002 and 2003 eruptions. Presently three types of Thermal-Infrared image based surveillance systems are in operation at Etna and Stromboli. They are focused to identify, classify and quantify different types of explosive events from small strombolian explosions to large volcanic-cloud forming eruptions. VAMOS on-line image analyzer that operates detection and classification of the strombolian explosive events in real-time. The analysis include the counting of the explosions occurred at the different craters of Stromboli and the parameterization in classes of intensity for each explosion on the base of clast dispersion and kinetics energy. A week report of the trend of the volcanic activity is available at INGV web. SARATERM on-line analyzer of thermal images for recognizing, in function of the temperature, the emission of spatter, ashes or gas from the summit craters of Etna and Stromboli. This system is presently used to alert in real-time the on-duty volcanologists. Finally a network of IR cameras working in selected narrow bands of the thermal IR spectra, will be put in operation soon around Etna for the detection and discrimination of volcanic ash clouds from meteorological ones.