The 15 March 2007 explosive crisis at Stromboli volcano, Italy: Assessing physical parameters through a multidisciplinary approach

Abstract

[1] Basaltic volcanoes are dominated by lava emission and mild explosive activity. Nevertheless, many basaltic systems exhibit, from time to time, poorly documented and little-understood violent explosions. A short-lived, multiblast explosive crisis (paroxysmal explosion) occurred on 15 March 2007 during an effusive eruptive crisis at Stromboli (Italy). The explosive crisis, which started at 20:38:14 UT, had a total duration of $5 min. The combined use of multiparametric data collected by the permanent instrumental networks (seismic, acoustic, and thermal records) and a field survey carried out immediately after the event enabled us to constrain the eruptive dynamics and quantify physical parameters. The eruption consisted of three major pulses: In the first, lithic blocks and ash were ejected at speeds of 100-155 m/s and 130-210 m/s, respectively. The high solid load of the eruptive jet resulted in the partial collapse of the column with the formation of a small-volume pyroclastic density current. The second, 12 s long pulse emitted 2.2-2.7 Â 10 7 kg of tephra (mass discharge rate = 1.9-2.3 Â 10 6 kg/s), forming a 3 km high convective plume, dispersing tephra up to the west coast, and a dilute density current with limited dispersal downslope of the craters. A final, 30 s long phase formed a scoria flow with a volume of 1.5-1.7 Â 10 4 m 3 (mass discharge rate = 5.9-6.7 Â 10 5 kg/s), a total runout of $200 m, and a velocity of 45 m/s. The total gas volume involved in the explosion was 1.3-1.9 Â 10 4 m 3 with an initial overpressure of 7.9 AE 0.4 MPa. We compared the 15 March 2007 event with historical paroxysms, in particular with that of 5 April 2003, which was remarkably similar.

New Advances in Dial-Lidar-Based Remote Sensing of the Volcanic CO2 Flux

“…As longer-term volcanic gas records increase in number and quality, full empirical evidence is finally emerging for increased CO 2 flux emissions prior to eruption of mafic to intermediate volcanoes (Aiuppa, 2015). Precursory plume CO 2 flux increases have been now detected at several volcanoes, including Etna (Aiuppa et al, 2008;Patanè et al, 2013), Kilauea (Poland et al, 2012), Redoubt (Werner et al, 2013), Turrialba (de Moor et al, 2016a), and Poas (de Moor et al, 2016b).At Stromboli (in Italy), however, CO 2 flux observations have been particularly valuable for interpreting, and eventually predicting, the volcano's behavior (Aiuppa et al, 2010a Stromboli, the "regular" mild strombolian activity is occasionally interrupted by larger-scale vulcanian-style explosions, locally referred as "major explosions" or (in the most extreme events) "paroxysms" (Rosi et al, 2006(Rosi et al, , 2013Andronico and Pistolesi, 2010;Pistolesi et al, 2011;Pioli et al, 2014). These explosions, although short-lived (tens of seconds to a few minutes), represent a real hazard for local populations, tourists and volcanologists, since they produce fallout of coarse pyroclastic materials over wide dispersal areas (Rosi et al, 2013).…”

“…At Stromboli (in Italy), however, CO 2 flux observations have been particularly valuable for interpreting, and eventually predicting, the volcano's behavior (Aiuppa et al, 2010a Stromboli, the "regular" mild strombolian activity is occasionally interrupted by larger-scale vulcanian-style explosions, locally referred as "major explosions" or (in the most extreme events) "paroxysms" (Rosi et al, 2006(Rosi et al, , 2013Andronico and Pistolesi, 2010;Pistolesi et al, 2011;Pioli et al, 2014). These explosions, although short-lived (tens of seconds to a few minutes), represent a real hazard for local populations, tourists and volcanologists, since they produce fallout of coarse pyroclastic materials over wide dispersal areas (Rosi et al, 2013).…”

Radon mapping, automatic measurements and extremely high 222Rn emissions during the 2002–2007 eruptive scenarios at Stromboli volcano

“…This activity may be occasionally replaced by lava flows and more energetic explosions with the eruption of larger volumes of scoria-bombs, blocks and ash, named "paroxysms". Their onset is usually accompanied by the ejection of eruptive columns with the projection of blocks of several tons that may reach the villages on the coast of the island (Barberi et al, 1993;Rosi et al, 2006;Pistolesi et al, 2011). However, flank slumping and related tsunamis occurred during several recent lava effusions (namely in 1879, 1916, 1919, 1930, 1944 and 1954, according to Barberi et al, 1993).…”

Syn-eruptive, soft-sediment deformation of deposits from dilute pyroclastic density current: triggers from granular shear, dynamic pore pressure, ballistic impacts and shock waves

“…Interestingly, the high deposition rates combined with possible fluidized state of the flow can trap gases in the deposits that subsequently escape as degassing pipes within seconds after deposition (Komorowski et al, 2013). These can occur as fines-depleted pipes, a few centimeters in length and diameter (Pistolesi et al, 2011;Smith and Kokelaar, 2013), or large decimeter-meter scale depressions at the surface of deposits (Charbonnier and Gertisser, 2008). The high deposition rates also trigger simple load casts (Mattsson and Tripoli, 2011).…”