Infrasonic Long-Range Observations at IS42: Study Cases of Grimsvötn (Iceland), Mt. Etna and Stromboli Volcanoes (Italy)

The collaborative research UNIFI–University of the Azores (IVAR) focused on the detection and characterization of events injecting energy into the atmosphere and allowed to analyze of the Grímsvötn volcano eruptive activity (Iceland) and Mt. Etna and Stromboli volcanoes (Italy) by several Stations (among which IS42) of the CTBTO’s International Monitoring System (IMS). Grímsvötn volcano, located under the Vatnajökull glacier, is the most active Icelandic volcano. The May 2011 explosive eruption broke the ice-covering and turned into sub-aerial, ejecting ash into the atmosphere and restricting flights across Northwestern Europe and the North Atlantic region. Mt. Etna, located in Sicily Island (Italy), is Europe’s largest and most active volcano. It is typically effusive with explosive episodes, and lava fountaining activity has recently produced high eruptive plumes causing an impact on local air traffic and nearby airports and cities. Finally, Stromboli volcano (Italy), located in one of the Aeolian Islands (Italy) with the same name, is one of the most active volcanoes on Earth, with sustained explosive activity and permanent degassing. A strong explosive event characterized by two distinct explosions occurred on July 3rd, 2019. In this study, we describe a multiple-detections analysis of (a) the May 2011 Grímsvötn eruption as observed at IS42 and other infrasound stations and its correlations with on-site observations; (b) the Mt. Etna eruptive activity of the May–September 2011 and the 2016 eruptions, as observed at IS42 and other stations, compared with near-source observations; and (c) the Stromboli July 3rd, 2019 event detections from IS42 and other IMS infrasound stations. We relate those results with events listed in the CTBTO Reviewed Event Bulletin (REB) to evaluate the potential of the IMS network in detecting and identifying sources of volcanic activity. In the framework of earth-based volcanic monitoring techniques, infrasound is a unique technology with the potential to detect explosive eruptions at great distances. Furthermore, simultaneous infrasound recording in near- and far-field represents a substantial improvement in the characterization of explosive sources.