Understanding the SO2 Degassing Budget of Mt Etna's Paroxysms: First Clues From the December 2015 Sequence

The persistent open-vent activity of Mt. Etna volcano, in Sicily, is frequently punctuated by some of the most spectacular paroxysmal basaltic explosions in nature. Although magmatic gas is unquestionably the driver of these events, direct measurements of a paroxysm’s gas flux budget have remained challenging and limited in number, to date. A particularly violent paroxysmal sequence took place on Etna on December 2015, intermittently involving four of its summit craters, especially the Voragine (VOR) that had previously displayed no activity for several years. Here, we characterize the volcano’s SO2 degassing budget prior to, during and after this paroxysmal sequence, using ground-based (UV-Camera) and satellite (OMI) observations, complemented with thermal (thermal cameras and MODIS) measurements from both ground and space. We make use of the high spatial resolution of UV-cameras to resolve SO2 emissions from the erupting VOR crater for the first time, and to characterize temporal switches in degassing activity from VOR to the nearby New Southeast Crater (NSEC). Our data show that onset of paroxysmal activity on December 3-5 was marked by visible escalation in VOR SO2 fluxes (4700-8900 tons/day), in satellite-derived thermal emissions (2000 MW vs. ~2-11 MW July-November 2015 average), and in OMI-derived daily SO2 masses (5.4±0.7 to 10.0±1.3 kilotonnes, kt; 0.5 kt was the average in the pre-eruptive period). Switch in volcanic activity from VOR to NSEC on December 6 was detected by increasing SO2 fluxes at the NSEC crater (up to 3460±350 tons/day), and by decaying SO2 emissions at VOR, until activity termination on December 19. Taken together, our observations infer the total degassed SO2 mass for the entire VOR paroxysmal sequence at 21,000±2730 t, corresponding to complete degassing of ~1.9±0.3 Mm3 of magma, or significantly less than the measured erupted magma volumes (5.1-12 Mm3). From this mismatch, we propose that a sizeable fraction of the erupted magma during the paroxysms was stored and degassed in the volcano’s shallow plumbing system well before eruption.

[1]  P. Allard.  Endogenous magma degassing and storage at Mount Etna , 1997 .

[2]  H. Shinohara.  Volatile flux from subduction zone volcanoes: Insights from a detailed evaluation of the fluxes from volcanoes in Japan , 2013 .

[3]  S. Carn,et al.  Characterising volcanic cycles at Soufriere Hills Volcano, Montserrat: Time series analysis of multi-parameter satellite data , 2015 .

[4]  Mike Burton,et al.  Open-path FTIR spectroscopy of magma degassing processes during eight lava fountains on Mount Etna , 2015 .

[5]  R. Wright,et al.  Satellite observations reveal little inter-annual variability in the radiant flux from the Mount Erebus lava lake , 2008 .

[6]  L. Keszthelyi,et al.  Calculation of lava effusion rates from Landsat TM data , 1998 .

[7]  D. Eatough,et al.  The Conversion of SO2 to Sulfate in the Atmosphere , 1994 .

[8]  A. Harris,et al.  Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? , 2002 .

[9]  Bruno Ando,et al.  An advanced video-based system for monitoring active volcanoes , 2006, Comput. Geosci..

[10]  S. Carn,et al.  A global catalogue of large SO 2 sources and emissions derived from theOzone Monitoring Instrument , 2016 .

[11]  M. Pompilio,et al.  Dynamics of magmas at Mount Etna , 2013 .

[12]  Salvatore Gambino,et al.  Mount Etna 1993–2005: Anatomy of an evolving eruptive cycle , 2006 .

[13]  M. James,et al.  Hawaiian and Strombolian Eruptions , 2015 .

[14]  E. Parfitt,et al.  A discussion of the mechanisms of explosive basaltic eruptions , 2004 .

[15]  Tommaso Caltabiano,et al.  SO2 flux measurements at Mount Etna (Sicily) , 1994 .

[16]  Mike Burton,et al.  The SO2 camera: A simple, fast and cheap method for ground‐based imaging of SO2 in volcanic plumes , 2006 .

[17]  Sonia Calvari,et al.  Eruptive processes leading to the most explosive lava fountain at Etna volcano: The 23 November 2013 episode , 2014 .

[18]  D. Suckling,et al.  Thigmotaxis Mediates Trail Odour Disruption , 2017, Scientific Reports.

[19]  J. Phillips,et al.  Degassing processes during lava dome growth: Insights from Santiaguito lava dome, Guatemala , 2011 .

[20]  Mike Burton,et al.  Spectroscopic evidence for a lava fountain driven by previously accumulated magmatic gas , 2005, Nature.

[21]  Boris Behncke,et al.  The 2011-2012 summit activity of Mount Etna: Birth, growth and products of the new SE crater☆ , 2014 .

[22]  Mike Burton,et al.  Effects of a volcanic plume on thermal imaging data , 2006 .

[23]  Mauro Coltelli,et al.  Doppler radar sounding of volcanic eruption dynamics at Mount Etna , 2004 .

[24]  Giorgio Lacanna,et al.  Exploring the explosive‐effusive transition using permanent ultra‐violet cameras , 2017 .

[25]  Boris Behncke,et al.  The exceptional activity and growth of the Southeast Crater, Mount Etna (Italy), between 1996 and 2001 , 2006 .

[26]  Maurizio Ripepe,et al.  Infrasound reveals transition to oscillatory discharge regime during lava fountaining: Implication for early warning , 2013 .

[27]  S. Self,et al.  The October 1902 plinian eruption of Santa Maria volcano, Guatemala , 1983 .

[28]  Michael J. Garay,et al.  MISR observations of Etna volcanic plumes , 2012 .

[29]  Robert Wright,et al.  Space-based estimate of the volcanic heat flux into the atmosphere during 2001 and 2002 , 2004 .

[30]  J. Martí,et al.  Years to weeks of seismic unrest and magmatic intrusions precede monogenetic eruptions , 2016 .

[31]  Mike Burton,et al.  2001 flank eruption of the alkali- and volatile-rich primitive basalt responsible for Mount Etna's evolution in the last three decades , 2004 .

[32]  D. Lenschow,et al.  Sulfur dioxide in the tropical marine boundary layer: dry deposition and heterogeneous oxidation observed during the Pacific Atmospheric Sulfur Experiment , 2009 .

[33]  S. Carn,et al.  A decade of global volcanic SO2 emissions measured from space , 2017, Scientific Reports.

[34]  M. Spalla,et al.  Numerical simulations of an ocean‐continent convergent system: Influence of subduction geometry and mantle wedge hydration on crustal recycling , 2010, 1106.4679.

[35]  R. Hervig,et al.  Explosive basaltic volcanism from Cerro Negro volcano: Influence of volatiles on eruptive style , 1997 .

[36]  R. Carluccio,et al.  The continuing story of Etna's New Southeast Crater (2012–2014): Evolution and volume calculations based on field surveys and aerophotogrammetry , 2015 .

[37]  Gaetana Ganci,et al.  The initial phases of the 2008–2009 Mount Etna eruption: A multidisciplinary approach for hazard assessment , 2011 .

[38]  S. Carn,et al.  Extending the long‐term record of volcanic SO2 emissions with the Ozone Mapping and Profiler Suite nadir mapper , 2015 .

[39]  Daniele Andronico,et al.  Relationship between tremor and volcanic activity during the Southeast Crater eruption on Mount Etna in early 2000 , 2003 .

[40]  H. Rymer,et al.  Balancing bulk gas accumulation and gas output before and during lava fountaining episodes at Mt. Etna , 2015, Scientific reports.

[41]  Takeo Kanade,et al.  An Iterative Image Registration Technique with an Application to Stereo Vision , 1981, IJCAI.

[42]  M. Ripepe,et al.  Synergy of multiple geophysical approaches to unravel explosive eruption conduit and source dynamics – A case study from Stromboli , 2007 .

[43]  D. Coppola,et al.  Magmatic degassing, lava dome extrusion, and explosions from Mount Cleveland volcano, Alaska, 2011–2015: Insight into the continuous nature of volcanic activity over multi-year timescales , 2017 .

[44]  D. Andronico,et al.  Lava fountains during the episodic eruption of South–East Crater (Mt. Etna), 2000: insights into magma-gas dynamics within the shallow volcano plumbing system , 2011 .

[45]  Hiren Jethva,et al.  Impact of the ozone monitoring instrument row anomaly on the long-term record of aerosol products , 2017 .

[46]  I. Watson,et al.  Multiparameter quantification of gas release during weak Strombolian eruptions at Pacaya Volcano, Guatemala , 2010 .

[47]  B. Chouet,et al.  Seismic source dynamics of gas‐piston activity at Kı̄lauea Volcano, Hawai‘i , 2015 .

[48]  Philippe Labazuy,et al.  An unloading foam model to constrain Etna’s 11–13 January 2011 lava fountaining episode , 2011 .

[49]  J. Taddeucci,et al.  High‐speed imaging of Strombolian eruptions: Gas‐pyroclast dynamics in initial volcanic jets , 2015 .

[50]  Donald B. Campbell,et al.  Mercury's moment of inertia from spin and gravity data , 2012 .

[51]  S. Carn,et al.  Improving global detection of volcanic eruptions using the Ozone Monitoring Instrument (OMI) , 2016 .

[52]  Mike Burton,et al.  Volcanic Gas Emissions from the Summit Craters and Flanks of Mt. Etna, 1987–2000 , 2004 .

[53]  G Tamburello,et al.  Spatially resolved SO2 flux emissions from Mt Etna , 2016, Geophysical research letters.

[54]  Mauro Coltelli,et al.  Discovery of a Plinian basaltic eruption of Roman age at Etna volcano, Italy , 1998 .

[55]  J. L. Palma,et al.  Open-vent volcanism and related hazards: Overview , 2013 .

[56]  M. Ripepe,et al.  Enhanced volcanic hot-spot detection using MODIS IR data: results from the MIROVA system , 2015, Special Publications.

[57]  W. Hocking,et al.  A Multi-diagnostic Investigation of Mesospheric Bore Phenomenon , 2003 .

[58]  C. Oppenheimer,et al.  A reassessment of current volcanic emissions from the Central American arc with specific examples from Nicaragua , 2006 .

[59]  A. Harris,et al.  Lava discharge rates from satellite‐measured heat flux , 2009 .

[60]  Christoph Kern,et al.  Network for Observation of Volcanic and Atmospheric Change (NOVAC)—A global network for volcanic gas monitoring: Network layout and instrument description , 2010 .

[61]  S. Carn,et al.  Multi-decadal satellite measurements of global volcanic degassing , 2016 .

[62]  Roberto de Bonis,et al.  The Use of Surveillance Cameras for the Rapid Mapping of Lava Flows: An Application to Mount Etna Volcano , 2017, Remote. Sens..

[63]  Taku Urabe,et al.  Relation between single very‐long‐period pulses and volcanic gas emissions at Mt. Asama, Japan , 2011 .

[64]  Arlin J. Krueger,et al.  Retrieval of large volcanic SO2 columns from the Aura Ozone Monitoring Instrument: Comparison and limitations , 2007 .

[65]  Mike Burton,et al.  Quantification of the gas mass emitted during single explosions on Stromboli with the SO2 imaging camera , 2009 .

[66]  Clive Oppenheimer,et al.  Sulfur Degassing From Volcanoes: Source Conditions, Surveillance, Plume Chemistry and Earth System Impacts , 2011 .

[67]  A. Harris,et al.  Thirty years of satellite‐derived lava discharge rates at Etna: Implications for steady volumetric output , 2011 .

[68]  M. Manga,et al.  Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin , 2012 .

[69]  B. Houghton,et al.  The influence of conduit processes on changes in style of basaltic Plinian eruptions: Tarawera 1886 and Etna 122 BC , 2004 .

[70]  Mike Burton,et al.  SO2 flux monitoring at Stromboli with the new permanent INGV SO2 camera system: A comparison with the FLAME network and seismological data , 2015 .

[71]  E. Cottrell,et al.  Ten years of satellite observations reveal highly variable sulphur dioxide emissions at Anatahan Volcano, Mariana Islands , 2015 .

[72]  P. Bhartia,et al.  Impact of the ozone monitoring instrument row anomaly on the long-term record of aerosol products , 2017 .

[73]  S. Carn,et al.  Daily monitoring of Ecuadorian volcanic degassing from space , 2008 .

[74]  Andrea Cannata,et al.  Insights into magma and fluid transfer at Mount Etna by a multiparametric approach: A model of the events leading to the 2011 eruptive cycle , 2013 .

[75]  M. Burton,et al.  Degassing dynamics of basaltic lava lake at a top-ranking volatile emitter: Ambrym volcano, Vanuatu arc , 2016 .

[76]  Division on Earth,et al.  Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing , 2017 .

[77]  Can Li,et al.  New-generation NASA Aura Ozone Monitoring Instrument (OMI) volcanic SO 2 dataset: algorithm description, initial results, and continuation with the Suomi-NPP Ozone Mapping and Profiler Suite (OMPS) , 2016 .

[78]  A. Harris,et al.  Automated volcanic eruption detection using MODIS , 2001 .

[79]  A. Freundt,et al.  The Masaya Triple Layer: a 2100 year old basaltic multi-episodic Plinian eruption from the Masaya Caldera Complex (Nicaragua) , 2009 .

[80]  D. Andronico,et al.  Alert system to mitigate tephra fallout hazards at Mt. Etna Volcano, Italy , 2007 .

[81]  Mike Burton,et al.  SO2 flux from Stromboli during the 2007 eruption: Results from the FLAME network and traverse measurements , 2009 .

[82]  A. McGonigle,et al.  Passive vs. active degassing modes at an open-vent volcano (Stromboli, Italy) , 2012 .

[83]  Massimo Pompilio,et al.  Magma dynamics within a basaltic conduit revealed by textural and compositional features of erupted ash: the December 2015 Mt. Etna paroxysms , 2017, Scientific Reports.

[84]  Duncan J. Wingham,et al.  Importance of seasonal and annual layers in controlling backscatter to radar altimeters across the percolation zone of an ice sheet , 2006 .

[85]  David Y. Hollinger,et al.  Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over four flux towers in the United States , 2011 .

[86]  Placido Montalto,et al.  Patterns in the recent 2007–2008 activity of Mount Etna volcano investigated by integrated geophysical and geochemical observations , 2010 .

[87]  A. Harris,et al.  Evolution of lava flow-fields at Mount Etna, 27–28 October 1999, observed by Landsat 7 ETM+ , 2001 .

[88]  M. Neri,et al.  Topographic Maps of Mount Etna’s Summit Craters, updated to December 2015 , 2017 .

[89]  H. Gonnermann,et al.  Explosive volcanism may not be an inevitable consequence of magma fragmentation , 2003, Nature.

[90]  Simona Scollo,et al.  Monitoring the December 2015 summit eruptions of Mt. Etna (Italy): Implications on eruptive dynamics , 2017 .

[91]  P. Allard,et al.  S-Cl-F degassing pattern of water-rich alkali basalt: Modelling and relationship with eruption styles on Mount Etna volcano , 2006 .

[92]  Mike Burton,et al.  Remote measurement of volcanic gases by Fourier transform infrared spectroscopy , 1998 .

[93]  M. Wooster,et al.  Fire radiative energy for quantitative study of biomass burning: derivation from the BIRD experimental satellite and comparison to MODIS fire products. , 2003 .

[94]  Sonia Calvari,et al.  Major effusive eruptions and recent lava fountains: Balance between expected and erupted magma volumes at Etna volcano , 2013 .

[95]  Sonia Calvari,et al.  A new approach to investigate an eruptive paroxysmal sequence using camera and strainmeter networks: Lessons from the 3–5 December 2015 activity at Etna volcano , 2017 .

[96]  F. Costa,et al.  Constraints on the Nature and Evolution of the Magma Plumbing System of Mt. Etna Volcano (1991-2008) from a Combined Thermodynamic and Kinetic Modelling of the Compositional Record of Minerals , 2015 .

[97]  Lopaka Lee,et al.  An automated SO 2 camera system for continuous, real-time monitoring of gas emissions from Kīlauea Volcano's summit Overlook Crater , 2015 .

[98]  L. G. Tilstra,et al.  The Ozone Monitoring Instrument : Overview of twelve years in space , 2017 .

[99]  Mike Burton,et al.  Three-years of SO2 flux measurements of Mt. Etna using an automated UV scanner array: Comparison with conventional traverses and uncertainties in flux retrieval , 2009 .

[100]  D. Coppola,et al.  Tracking Formation of a Lava Lake From Ground and Space: Masaya Volcano (Nicaragua), 2014–2017 , 2018 .

[101]  S. Carn,et al.  Evaluation of Redoubt Volcano's sulfur dioxide emissions by the Ozone Monitoring Instrument , 2013 .

[102]  A. McGonigle,et al.  UV camera measurements of fumarole field degassing (La Fossa crater, Vulcano Island) , 2011 .

[103]  D. Coppola,et al.  Rheological control on the radiant density of active lava flows and domes , 2013 .

[104]  Heikki Saari,et al.  The ozone monitoring instrument , 2006, IEEE Transactions on Geoscience and Remote Sensing.

[105]  Andrew J. S. McGonigle,et al.  Correlation of oscillatory behaviour in Matlab using wavelets , 2014, Comput. Geosci..

[106]  Andrea Cannata,et al.  Multiparametric study of the February–April 2013 paroxysmal phase of Mt. Etna New South‐East crater , 2015 .

[107]  S. Carn,et al.  Measuring global volcanic degassing with the Ozone Monitoring Instrument (OMI) , 2013 .

[108]  Michele Prestifilippo,et al.  Near-source Doppler radar monitoring of tephra plumes at Etna , 2016 .

[109]  D. Andronico,et al.  Coupled textural and compositional characterization of basaltic scoria: Insights into the transition from Strombolian to fire fountain activity at Mount Etna, Italy , 2006 .

[110]  Christoph Kern,et al.  On the absolute calibration of SO 2 cameras , 2012 .

[111]  Andrea Cannata,et al.  The unusual 28 December 2014 dike-fed paroxysm at Mount Etna: Timing and mechanism from a multidisciplinary perspective , 2016 .

[112]  A. Harris,et al.  Shallow system rejuvenation and magma discharge trends at Piton de la Fournaise volcano (La Réunion Island) , 2017 .

[113]  Robert G. Bryant,et al.  Protocols for UV camera volcanic SO2 measurements , 2010 .

[114]  Diego Coppola,et al.  Analysis of volcanic activity patterns using MODIS thermal alerts , 2005 .

[115]  A. Harris,et al.  Lava effusion rate definition and measurement: a review , 2007 .

[116]  Joachim Weickert,et al.  Lucas/Kanade Meets Horn/Schunck: Combining Local and Global Optic Flow Methods , 2005, International Journal of Computer Vision.

[117]  Giancarlo Neri,et al.  Satellite analysis and PUFF simulation of the eruptive cloud generated by the Mount Etna paroxysm of 22 July 1998 , 2002 .

[118]  B. Behncke,et al.  Complex magma dynamics at Mount Etna revealed by seismic, thermal, and volcanological data , 2009 .

[119]  Maurizio Ripepe,et al.  Infrasonic evidences for branched conduit dynamics at Mt. Etna volcano, Italy , 2009 .

[120]  S. Carn,et al.  First synoptic analysis of volcanic degassing in Papua New Guinea , 2012 .

[121]  Gianfranco Vulpiani,et al.  Mass discharge rate retrieval combining weather radar and thermal camera observations , 2016 .

[122]  R. Andres,et al.  The effects of volcanic ash on COSPEC measurements , 2001 .