Precursory diffuse CO₂ and H₂S emission signatures of the 2011–2012 El Hierro submarine eruption, Canary Islands

Abstract

On October 12, 2011, a submarine eruption began 2 km off the coast of La Restinga, south of El Hierro Island. CO2 and H2S soil efflux were continuously measured during the period of volcanic unrest by using the accumulation chamber method at two different geochemical stations, HIE01 and HIE07. Recorded CO2 and H2S effluxes showed precursory signals that preceded the submarine eruption. Beginning in late August, the CO2 efflux time series started increasing at a relatively constant rate over one month, reaching a maximum of 19 gm−2d−1 one week before the onset of the submarine volcanic eruption. The H2S efflux time series at HIE07 showed a pulse in H2S emission just one day before the initiation of the submarine eruption, reaching peak values of 42 mg m−2 d−1, 10 times the average H2S efflux recorded during the observation period. Since CO2 and H2S effluxes are strongly influenced by external factors, we applied a multiple regression analysis to remove their contribution. A statistical analysis showed that the long‐term trend of the filtered data is well correlated with the seismic energy. We find that these geochemical stations are important monitoring sites for evaluating the volcanic activity of El Hierro and that they demonstrate the potential of applying continuous monitoring of soil CO2 and H2S efflux to improve and optimize the detection of early warning signals of future volcanic unrest episodes at El Hierro. Continuous diffuse degassing studies would likely prove useful for monitoring other volcanoes during unrest episodes.

Deep intrusions, lateral magma transport and related uplift at ocean island volcanoes

“…Most hypocentres were initially located beneath the central island at 9-11 km depth, i.e., within the lower crust, but migrated southward and became deeper (11-16 km) and stronger between late September and October 9th (Lopéz et al, 2012). Phase 1 was accompanied by an increase in CO 2 , H 2 S and radon emissions (Lopéz et al, 2012;Pérez et al, 2012) and by ground deformation with a maximum uplift of ca. 10 cm around central El Hierro, which was largely retained during the eruptive period (González et al, 2013).…”

Computer Modeling of an Ion Trap Mass Analyzer, Part I: Low Pressure Regime

“…Standard diffuse degassing methods focus on detecting percolated CO 2 and H 2 S gas as precursors to volcanic eruptions [36]. Helium poses as a better indicator because it is absent from metabolic pathways of microorganisms and it is chemically inert in rocks.…”

Investigating the deepest part of a volcano plumbing system: Evidence for an active magma path below the western flank of Piton de la Fournaise (La Réunion Island)

“…Regarding the second type, many cases have been described by several authors at numerous volcanoes, such as, Mount Etna and Vulcano Island in Italy Chiodini et al, 1998;Diliberto et al, 2002;Gurrieri et al, 2008;Giammanco and Bonfanti, 2009;Cannata et al, 2010Cannata et al, , 2015, or El Hierro in the Canary Islands (López et al, 2012;Pérez et al, 2012). At Piton de la Fournaise (La Réunion Island), diffuse flank CO 2 degassing is generally very weak (Seidel et al, 1988;Marty et al, 1993;Toutain et al, 2002;Liuzzo et al, 2015 ) and includes a significant biogenic component.…”