The initial phases of the 2008–2009 Mount Etna eruption: A multidisciplinary approach for hazard assessment

Abstract

[1] Between 2007 and early 2008, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) monitoring networks on Etna volcano recorded a recharging phase that climaxed with a new effusive eruption on 13 May 2008 and lasted about 14 months. A dike-forming intrusion was accompanied by a violent seismic swarm, with more than 230 events recorded in the first 6 h, the largest being M L = 3.9. In the meanwhile, marked ground deformation was recorded by the permanent tilt and GPS networks, and sudden changes in the summit area were detected by five continuously recording magnetic stations. Poor weather conditions did not allow direct observation of the eruptive events, but important information was provided by infrared satellite images that detected the start of lava fountains from the eruptive fissure, feeding a lava flow. This flow spread within the Valle del Bove depression, covering 6.4 km on the southeastern flank of the volcano in a few hours. The seismicity and deformation pattern indicated that the dike-forming intrusion was propagating northward. It produced a dry fracture field, which generated concern for the possibility that the eruptive fissures could expand downslope toward populated areas. Monitoring and modeling of the multidisciplinary data, together with the simulations of ash dispersal and lava flows, allowed us both to infer the eruptive mechanisms and to provide correct interpretation of the ongoing phenomena, furnishing useful information for civil defense purposes. We describe how this approach of feedback between monitoring and research provides critical support to risk evaluation.

Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006–2009

“…Some facts should be pointed out. First, a stagnant and non-convective magma body does not necessarily fit with enhanced seismic activity and ash emission in spring 2006 (www.ingv.ct.it and observation of ash emission by N. Bobrowski in April 2006 andBonaccorso et al, 2011). Second, the authors have just one data point for the whole month of April 2006, which could have led to a misleading interpretation.…”

“…7 by including our visual observations and geophysical data published by e.g. Bonforte et al (2008), Aloisi et al (2009), Aiuppa et al (2010, Bonaccorso et al (2011).…”

“…(Bonforte et al, 2008;Bonaccorso et al, 2011) which was interpreted as a period of new magma uprise. For our data set that could mean that magma reached in April 2006 the level where a significant amount of bromine starts to be exsolved.…”

A year of lava fountaining at Etna: Volumes from SEVIRI

“…The recent availability of mid-and thermal-infrared data at a frequency of 15 minutes from geostationary platforms, such as GOES, MTSAT and Meteosat Second Generation, have allowed the construction of lava discharge rate time series during such short-lived fountain-fed effusive events [Bonaccorso et al, 2011a;Calvari et al, 2011;Gouhier et al, 2012;Vicari et al, 2011]. The same time-series can be used to yield volume and intensity, with the continuous presence of the satellite sensor in a fixed-position geostationary orbit meaning that data are always available for the targeted location.…”

Why Does a Mature Volcano Need New Vents? The Case of the New Southeast Crater at Etna

“…Geodetic measurements on the summit part of Etna are possible only in the summer, due to the snow cover during the rest of the year that prevents the access to the highest GPS points. The ground deformation here analyzed has been previously described in terms of displacements of the measurement stations (Bonforte et al, 2008Bonaccorso et al, 2011Bonaccorso et al, , 2015. Conversely, here we calculate the horizontal strain tensor components by the GridStrain routine developed by Pesci and Teza (2007), already used for investigating the surface deformation of the eastern flank of Etna by Alparone et al (2011).…”