OF GEOPHYSICS,2011, 175-185, 52, 2, doi 10.4401/ag-5183. Inguaggiato S., Mazot A., Diliberto I.S., Inguaggiato C., Madonia P., Rowet D., Vita F., Total CO2.
42nd Workshop of the International School of Geophysics Volcano Observatory Best Practices Workshop #2: Communicating Hazards Erice, Sicily (IT), 02 - 06 November 2013 Monitoring of geochemical parameters at La fossa cone (Vulcano island) Diliberto I.S., Inguaggiato S., Camarda M., Vita F., Calderone L.,Sollami A. 1
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Via Ugo la Malfa 153, Italy
Vulcano island (Aeolian Archipelago, South Mediterranean), is a quiescent volcanic edifice (last eruption dated 1888-90) located in a very active geodynamic region, at the boundary between the Eurasian and African tectonic plates. The high temperature field of Vulcano has frequently been the natural laboratory where our geochemical methods were tested. Moreover on Vulcano island, the geochemical data derived from the long term monitoring could provide the background reference to interpret the next time and/or space variation of volcanic activity. Indeed, long term volcanic surveillance program has provided both continuous monitoring of fumarole temperature and periodical determination of chemical and isotopic composition of released fluids (Diliberto et al. 2013 Paonita et al. 2013, Madonia et al., 2013). The monitoring of fumarole temperature at La Fossa crater showed a general decreasing trend of temperature from November 1998 (420 °C) to November 2000 (280 °C), thereafter positive trend started, with temperature increasing towards 470 °C, in September 2013. Besides these trends, frequent mean term variations of cyclic character have been recorded. Cyclic variations developed in few months. A direct time relationship has been observed among the cyclic increase of fumarole temperature and geochemical anomalies of magmatic origin (Paonita et al.2013). In the recent years, also CO2 flux from soil and SO2 flux measurements in the steam clouds ascending from the high temperature fumaroles have been monitored on a continuous time basis in a few fixed sites of the La Fossa cone. This work reports comparison of different parameters (fumaroles temperature, SO2 flux, CO2 flux from soil) acquired on the la Fossa cone. The time series were compared in order to highlight the episodic increases of convective energy release. A strong support to whomever is responsible for evaluating, managing and communicating hazards could come by multidisciplinary scientific approach. Both hazard estimation and eruption forecasting could better be addressed when the multi-parametric approach is afforded early before the expected crisis. In any case, in order to contribute to systems modelling, data from continuous monitoring requires necessary technical steps, like the accurate data validation and elaboration, before of any scientific interpretation.
Figures 1-10
VSCS
Fig 1 Digital Elevation Map of Vulcano, La Fossa crater and monitored fumaroles. The black stars are for thermal probe location (F5, F5AT, FA); the dots are for other monitoring stations in steam heated soil.
The monitoring of fumarole temperature at La Fossa crater showed a general decreasing trend of temperature from November 1998 (420 °C) to November 2000 (280 °C), thereafter positive trend started, with temperature increasing towards 470 °C, in September 2013. Besides these trends, frequent mean term variations of cyclic character have been recorded. Cyclic variations develops in few months.
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Fig. 3 Cyclic variations recorded at high temperature fumaroles field from October 1998 to December 1998 (1 FT). These data series come from fumaroles located on the edge of active cone.
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Fig. 4 CO2 content in fumaroles sampled at la Fossa cone from January 1998 to November 1999 (scale on the left axis) and cyclic temperature variations recorded by continuous monitoring (1 FT). The 4th order polynomial curves which best fitted recorded data are reported in red. T values have been normalized for easier comparing :
T / Tm = tx ÷ t n
Where t represents the background reference for each monitored site calculated as: being respectively, during 1988-1999:
t1 = 360°C
t 2 = 380°C
t 3 = 270°C
t = ∑t ÷ n 1
Fig. 5 – (from Cannata et al. 2012) a Daily number of volcano-seismic events; b Daily number of VT earthquakes (histogram) and cumulative seismic strain release (grey area); c Soil temperature at MN station; d Fumaroles temperature at F5AT station. The grey areas in d indicate periods characterized by strong rainfall.
Fig.6 CO2 concentration (vol%) and the Temperature of gas relesed by the F0 fumarole. The strong increase (up to 18 vol%) of CO2 concentration occurred concurrently with increases in CO2 soil fluxes and SO2 plume flux
Fig.7 SO2 flux and CO2 soil fluxes. The coinciding trends of these two independent parameters indicate an increase of volatiles degassed from depth. (From Inguaggiato et al., 2012)
8. Pictures of Vulcano island showing the positions of the UV-Scanning DOAS equipment: the scanning DOAS station, the weather station and the WLAN bridge for data transfer.
Fig.9 Photo of the summit of Vulcano’s active cone La Fossa (a); photo of VSCS (a station monitoring CO2 diffuse flux), during intervention for maintenance (b); DEM of Vulcano Island showing the location of installed equipment (c); contour plot of La Fossa crater CO2 flux measurements (d).
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Time variations of fumarole temperatures, detrended according to the best fitting linear equation: TDT3 = 0.0461x – 1447.
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Real time volcanic SO2 flux (t.d—1) measured by the UV-scanning DOAS equipment installed on the south-east flank of the active cone in the framework of the NOVAC project
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Daily average values of summit CO2 flux measured at Bordosud and ambient temperature measured inside the station (yellow line – scale on the right axis)
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Fig 10 The time variations recorded during the last two years have been plotted at comparable time scale for a multiparametric visual comparison. Respect to their background values all these stations located on top of la Fossa cone showed the same period of anomalous degassing levels. References Cannata A., Diliberto I.S., Alparone S., gambino S., Gresta S., Liotta M., Madonia P., Milluzzo V., Aliotta M., Montalto P., Multiparametric Approach in Investigating Volcano-Hydrothermal
Systems: the Case Study of Vulcano (Aeolian Islands, Italy). PURE AND APPLIED GEOPHYSICS, 2012, 167-182, 169 10.1007/s00024-011-0297-z Diliberto I.S., Time series analysis of high temperature fumaroles monitored on the island of Vulcano (Aeolian Archipelago, Italy). JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 2013, 150-163, 264,10.1016/j.jvolgeores.2013.08.003. Diliberto I.S., Long-term variations of fumarole temperatures on Vulcano Island (Italy). ANNALS OF GEOPHYSICS,2011, 175-185, 52, 2, doi 10.4401/ag-5183 Inguaggiato S., Mazot A., Diliberto I.S., Inguaggiato C., Madonia P., Rowet D., Vita F., Total CO2 output from Vulcano island (Aeolian Islands, Italy). GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS, 2012, 1-19, 13, doi:10.1029/2011GC003920 Inguaggiato, S., Calderone, L., Inguaggiato, C., Mazot, A., Morici, S., Vita, F, Longtime variation of soil CO2 fluxes at the summit crater of Vulcano (Italy). Bulletin of Volcanology, 2012, 74, 1859–1863. http://dx.doi.org/10.1007/s00445-012-0637-6. Madonia P., Cusano P., Diliberto I.S., Cangemi M., Thermal anomalies in fumaroles at Vulcano island (Italy)and their relationship with seismic activity. PHYSICS AND CHEMISTRY OF THE EARTH, 2013, 160-169, 63, doi.org/10.1016/j.pce.2013.06.001. Paonita, A., Federico, C., Bonfanti, P., Capasso, G., Inguaggiato, S., Italiano, F., Madonia, P., Pecoraino, G., Sortino, F., The episodic and abrupt geochemical changes at la fossa fumaroles (Vulcano Island, italy) and related constraints on the dynamics, structure, and compositions of the magmatic system. Geochimica et CosmochimicaActa, 2013, 120, 158–178.
