ALBERT

Description: On 27 February 2007, at 12.49 GMT, a new eruption of Stromboli took place with the effusion of a lava flow from a fracture cutting the flank of the NE cone, which rapidly reached the sea. The eruption had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th of February. Short-term precursors were an increase in the rate of occurrence of small landslides within the “Sciara del Fuoco” scar on the North-western flank of the volcano. A new effusive vent opened at 18.30 GMT on the Sciara del Fuoco at an height of 400 m asl. The new lava emission caused the sudden termination of the summit flow and initiated a period of non-stationary lava outpouring which ended on 2 April, 2007. The eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases. On the 15th of March, the increase in lava outpouring, monitored by a thermal camera, heralded by 9 min the occurrence of a violent paroxysmal explosion with the formation of an impulsive eruption column and the emission of small pumices mingled with black scoriae. The pumice had a bulk composition similar to that of the lava and of the black scoriae, but with a distinct lower content of phenocrysts. A similar feature has been repeatedly observed during the major explosive paroxysms of Stromboli. Short term precursors of the paroxysm were recorded by strainmeter and tiltmeter stations. The volcano monitoring activity has been made by a joint team of researchers from the INGV sections of Catania, Napoli, Palermo and Rome, along with researchers from the Universities of Florence, Pisa, Roma Tre, and Palermo. The scientific activity was coordinated by a Synthesis Group made up by scientists responsible for the different monitoring techniques of INGV and Universities and by the volcanic experts of Commissione Nazionale Grandi Rischi of the Prime Minister Office (Civil Protection Department). The group made a daily evaluation of the state of the volcano and transmitted its recommendations to the Civil Protection Department (DPC). Several prevention measures were adopted by DPC, the main of which were the evacuation of the coast zone when strong acceleration of the Sciara del Fuoco slope motion (occurred twice) could led to a dangerous tsunami by flank collapse (as last occurred on 30 December 2002) and four days before the 15 March paroxysm when access was prohibited to the part of the volcano above 290 m asl.

Description: Published

Description: 123–130

Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce

Description: JCR Journal

Description: reserved

Description: On 27 February 2007, at 12.49 GMT, a new eruption of Stromboli took place with the effusion of a 15 lava flow from a fracture cutting the flank of the NE cone, which rapidly reached the sea. The eruption 16 had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th 17 of February. Short-term precursors were an increase in the rate of occurrence of small landslides within 18 the “Sciara del Fuoco” scar on the North-western flank of the volcano. A new effusive vent opened at 19 18.30 GMT on the Sciara del Fuoco at an height of 400 m asl. The new lava emission caused the 20 sudden termination of the summit flow and initiated a period of non-stationary lava outpouring which 21 ended on 2 April, 2007. The eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases. On the 15th 22 of March, the increase in 23 lava outpouring, monitored by a thermal camera, heralded by 9 minutes the occurrence of a violent 24 paroxysmal explosion with the formation of an impulsive eruption column and the emission of small 25 pumices mingled with black scoriae. The pumice had a bulk composition similar to that of the lava and 26 of the black scoriae, but with a distinct lower content of phenocrysts. A similar feature has been 27 repeateadly observed during the major explosive paroxysms of Stromboli. Short term precursors of the 28 paroxysm were recorded by strainmeter and tiltmeter stations. The volcano monitoring activity has 29 been made by a joint team of researchers from the INGV sections of Catania, Napoli, Palermo and 30 Rome, along with researchers from the University of Florence, Pisa, Roma Tre, and Palermo. The 31 scientific activity was coordinated by a Synthesis Group made up by the responsibles of the different 32 monitoring techniques of INGV and Universities and by the volcanic experts of Commissione Nazionale Grandi Rischi of the Prime Minister Office (Civil Protection Department). 33 The group made a 34 daily evaluation of the state of the volcano and transmitted its recommendations to the Civil Protection 35 Department (DPC). Several prevention measures were adopted by DPC, the main of which were the 36 evacuation of the coast zone when strong acceleration of the Sciara del Fuoco slope motion (occurred 37 twice) could led to a dangerous tsunami by flank collapse (as last occurred on 30 December 2002) and 38 four days before the 15 March paroxysm when access was prohibited to the part of the volcano above 39 290m asl

Description: In press

Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce

Description: 3.5. Geologia e storia dei sistemi vulcanici

Description: JCR Journal

Description: open

Description: On 28 December 2002, the persistent Strombolian activity at Stromboli was interrupted by the sudden onset of lava emission onto the Sciara del Fuoco slope, a horseshoe-shaped depression on the NW flank of the volcano. The effusive episode went on until 22 July 2003 and produced a cumulative volume of lavas of 11×106 m3 ranking the event as the largest occurred in the past 30 years. The eruptive vents were mainly located in the NE sector of the Sciara del Fuoco depression, at an elevation of 550–600 m a.s.l. On 30 December, the eastern portion of the Sciara del Fuoco collapsed producing a tsunamigenic landslide. On 5 April 2003, a paroxysmal eruption occurred at the summit craters during which crystal-poor pumiceous products were emitted. The paroxysm did not interrupt the lava emission. The Strombolian activity at the summit craters gradually resumed starting from March 2003 and fully recovered by the end of July. Periodic sampling of the lava at the active vents was carried out during the entire effusive event. All the analysed samples are shoshonitic basalts (SiO2 48.5–50.4 wt.%; K2O 2.1–2.4 wt.%) in the range of composition observed in the products erupted during the past 20 years. They bear about 50 vol.% zoned crystals of plagioclase An90–60, diopside–augite and olivine Fo70–73 in a compositionally homogeneous shoshonitic groundmass. Bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations. Sr and Nd isotope ratios are close to those of the crystal-rich scoriae erupted in the previous years. Despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit, the data show that the switch from Strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products. Slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 April eruption are likely accounted by limited mixing between the fresh, volatile-rich, crystal-poor, magma erupted as pumice during the paroxysm, and the volatile-poor, crystal-rich magma feeding the lava flow. The uniform composition of the erupted lava indicates the presence of a large volume of well-mixed, crystal-rich, homogeneous magma residing in the shallow plumbing system of the volcano. Two possible trigger mechanism of the effusive event are here proposed: (i) a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation, degassing and mixing with the crystal-rich shallow magma which re-homogenised the system. These processes eventually led to the rise of the magma at a higher level and failure of the conduit walls. (ii) The onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades. The process of progressive refilling, initiated after the 1985 effusive eruption, ultimately culminated on 28 December 2002 with the failure of the conduit wall and the opening of vents 100–150 m below the summit craters

Description: Published

Description: 263-284

Description: JCR Journal

Description: reserved